Internet DRAFT - draft-mcfadden-opsec-endp-evolve
draft-mcfadden-opsec-endp-evolve
Individual Submission M. McFadden
Internet Draft internet policy advisors, ltd uk
Intended status: Informational August 16, 2021
Expires: February 16, 2022
Evolution of Endpoint Security - An Operational Perspective
draft-mcfadden-opsec-endp-evolve-01.txt
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Abstract
This draft discusses the traditional model of security where
endpoints in the network are protected by a variety of tools. It
proposes a model for endpoints and then argues that the older,
traditional approach is no longer sufficient for operational
security at the endpoint. A series of operational examples are
discussed in an Appendix.
Table of Contents
1. Introduction...................................................3
2. Endpoints, Definition, Model and Scope.........................3
2.1. Scope.....................................................3
2.2. Models....................................................4
2.3. Internal representation of an endpoint....................4
2.4. External representation of an endpoint....................5
3. Limitations of the Threat Landscape............................6
3.1. Typical Categories of Threats.............................7
3.2. Evolution of threat types and their descriptions..........7
4. Endpoint Security Capabilities.................................8
4.1. Intrinsic versus added security...........................9
4.2. Specific Endpoint Security Capabilities..................10
5. Optimal Properties of an Endpoint Security Solution...........11
6. Case Studies in the Limitations of Endpoint Security Only.....12
6.1. Unable to put an endpoint security add-on on the UE......13
6.2. Endpoints may not see the malware on the endpoint........16
6.3. Endpoints may miss information leakage attacks...........18
6.4. Suboptimality and gray areas.............................20
7. Defense-in-depth from the perspective of protocol design......23
8. Endpoint security from the perspective of protocol design.....24
8.1. Simplicity of design is important........................25
8.2. Diversity in protocol design.............................25
8.3. Protocol design and failure of intermediaries............26
8.4. Protocol evolution.......................................26
9. Security Considerations.......................................26
10. IANA Considerations..........................................27
11. Acknowledgements.............................................27
12. References...................................................27
12.1. Informative References..................................27
Appendix A. Operational Experience and Endpoint Security.........31
A.1. Endpoint only incidents..................................32
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A.2. Security incidents detected primarily by network security
products......................................................33
1. Introduction
There is currently significant discussion of the evolution of the
Internet's treat model. The evolution of the Internet has brought
new approaches to transport, connectivity, service provision and the
type of devices connected to the Internet. This document is a
discussion of the capabilities and limitations of security solutions
based on the traditional strategy of protecting endpoint devices.
The typical approach of protecting endpoints is affected by the
evolution of those endpoints and the emergence of threats that do
not rely on exploits at the endpoints. The goal of this document is
to provide an operational perspective on this evolution.
The focus here will be capabilities and limitations of endpoint-only
security solutions and the impact of the evolution of the Internet's
threat model on operational security.
Our goal with this review is to describe the benefits and
limitations of endpoint security in the real world - from an
operational perspective - rather than in the abstract. We aim to
highlight security limitations that cannot be addressed by endpoint
solutions and to suggest how these may be mitigated with the concept
of a defence-in-depth approach, in order to increase the resilience
against attacks and data breaches.
Finally, this draft suggests how this approach might affect protocol
design.
2. Endpoints, Definition, Model and Scope
2.1. Scope
Endpoints are the origin and destination for a communication between
parties. This encompasses User Equipment (UE) and the Host at the
other end of the communication. This is a simplification of
operational experience in the real world. In fact, there is an
enormous variety of devices at the endpoints of communication of
parties. However, a generalized approach to endpoints is not only
possible, but the subject of other work in the IETF. For instance,
the TEEP Working Group [1] has attempted to describe a generalized
model for endpoints. As a companion to this work, a taxonomy of
endpoints [2] is also provided.
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The goal is to provide a uniform way to describe the security
properties of endpoints in order to also describe the threat model,
or attack surface, of those endpoints.
For example:
o The following would be considered UEs: a smartphone, a smart
device, any IoT device, a laptop, a desktop, a workstation, etc.
o Hosts might be represented by the following examples: physical
servers, virtual servers/machines, etc.
2.2. Models
In what follows, the discussion is limited to modeling the endpoints
that are User Equipment (UE) rather than hosts. Having a model for
Internet hosts is important but beyond the scope of this draft. The
goal is to have a generalized description of the endpoint, its
security properties, and the position of the endpoint in the
network.
In addition, there are two separate descriptions for the endpoint.
First, an internal view of the endpoint is provided and then a view
of the external model for the endpoint is suggested. This approach
provides a mechanism to cover the full attack surface and the threat
landscape for the endpoint.
2.3. Internal representation of an endpoint
The companion endpoint taxonomy draft [2] provides a hierarchy of
endpoint types, properties and capabilities. The taxonomy draft
begins from the simplification represented in the following diagram:
+----------------------------+
| Application |
+----------------------------+
| OS / Execution Environment |
+----------------------------+
| Hardware |
+----------------------------+
Internal Endpoint Model
Today there are an enormous set of combinations of Hardware, OS/EE
pairing, and Application layers, offering the user a vast set of
features with a wide spectrum of capabilities. One of the features
of the evolution of the Internet's threat model is that the variety
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of these combinations is an enormous change compared to one or two
decades ago.
The variety of combinations provide users with a rich set of new
capabilities. Applications designers can provide services that were
not possible even five years ago. However, with those new
capabilities come new risks: new vectors for delivery of attacks and
new attack surfaces at the endpoint.
The result is: the operational implications for endpoint security
have evolved as the capabilities and variety of endpoints has
expanded.
2.3.1. Applications as Endpoints
One of the other features of this evolution is that the application
layer has evolved in such a way that it can be an endpoint as well.
This has important operational security implications because prior
approaches to providing endpoint security emphasized "per-device"
security. In an evolved internet, the endpoint may be the
application with multiple applications running on a single piece of
User Equipment (UE). In this case, the threat model may be different
for individual applications - resulting in different threat
landscapes on a single device.
2.4. External representation of an endpoint
Section 2.3 describes a model for understanding the threat landscape
of an individual UE device. In order to provide a complete view of
the threat landscape there must also be a model for the connectivity
properties of the device. This is a view of the attack surface of
the device as viewed externally.
A representation of endpoints in an end-to-end context could look
like the following diagram:
+-------+ +---------------------+---------+
| Human | <- (1) -> | Digital Persona | Application | <- (2) ->
+-------+ +-----------+-------------------+
| User Equipment |
+-------------------------------+
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+----------------+ +----------------+
<- (2) -> | Network | <- (3) -> | Platform/Hosts |
| Infrastructure | +----------------+
+----------------+
External Endpoint Model
1. Humans have a user experience (UX) with the UE, starting with an
explicit or implicit Digital Persona, engaging with an application;
2. The application will have sessions through a network
infrastructure. There are no assumptions made about how the network
infrastructure is provisioned or what its properties are, (as an
example, it could include landlines, mobile networks, satellites,
etc.) nor are any assumptions made about the characteristics of
those sessions (for instance, unicast or multicast, or sessions
sourced from multiple hosts).
3. A platform consisting of many Hosts either physical or virtual
which ensures a large part of the end-to-end user experience.
In this end-to-end model we see that many other systems may have
interactions with the UE: the human, the UX, the digital persona,
the sessions, the intermediate network infrastructure, and the hosts
and applications at the destination.
This means that the operational security requirements for the model
have expanded significantly. The threat landscape is very large and
the attack surface will involve all the components and interactions
at any level of either model.
3. Limitations of the Threat Landscape
In sections 2.3 and 2.4 above we saw that the pace of evolution of
endpoints on the Internet has had a resulting change to the types
and properties of attacks on those endpoints. In the past, the
number of User Equipment (UE) was well-bounded and an approach to
operational security that addressed the endpoints made intuitive and
practical sense.
In today's Internet, the vast number and range of combinations that
the generic modeling in sections 2.3 and 2.4 offers us, makes
defining a threat landscape far more complicated. From an
operational perspective the prior approach of concentrating security
on endpoints may have to be reconsidered.
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3.1. Typical Categories of Threats
Any description of a threat model for endpoints must address
typical, well-known attacks such as:
o Malware (Trojans, viruses, backdoors, bots, etc.)
o Adware and spyware
o Exploits
o Phishing
o Script-based attacks
o Ransomware, local Denial of Service (DoS) attacks
o Denial of Service (DoS) attacks
o Malicious removable storage devices (USB)
o In memory attacks
o Rootkits and firmware attacks
o Scams and online fraud
o System abuse (staging/proxying)
3.2. Evolution of threat types and their descriptions
However, the threat landscape is not static. Like the endpoints
themselves, the threats evolve. It's difficult, for instance, to
decide if cryptojacking or coinmining belong as examples of attacks
in categories above. It is possible that they represent new
categories of attack. In either case, a model of endpoint security
must cope with a threat landscape that evolves as the properties of
the endpoints evolve.
There are frameworks for describing threats:
O MITRE Common Attack Pattern Enumeration Classification (CAPEC).
See [3]. CAPEC offers a hierarchical view of attack patterns by
domains which can match some aspects of both of our above models,
but we will need to identify those attacks that fit exactly in our
scope.
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O MITRE ATT&CK. See [4]. ATT&CK offers a very straightforward
categorized knowledge base of attacks, but it concentrates on the
enterprise attack chain, so we will need to do some work to extract
what we need.
In both cases, the frameworks do not address all of the threats that
can affect the security of a system, for example they do not cover:
routing hijacking, flooding, selective blocking, unauthorised
modification of data sent to an endpoint, etc.
Phishing is an example of the limitations of using this approach.
Phishing should be included as an attack, but while this is indeed
an attack that will materialize on an end-device through an
application (email, webmail, etc.), the real target of this attack
is not the device, but the human behind the digital persona.
4. Endpoint Security Capabilities
For the purpose of this draft, endpoint security capabilities are
the features that are used to protect the endpoint from attack.
Protection has many meanings, however it is important to distinguish
three different aspects of protection:
o Prevention - The attack doesn't succeed by intrinsic or explicit
security capabilities.
o Detection - The attack is happening or has happened and is
recorded and/or signaled to another component for action.
o Mitigation - Once detected, the attack can be halted or its
effects can at least be reduced or reversed.
For example, prevention methods include keeping the software updated
and patching vulnerabilities, implementing measures to authenticate
the provenance of incoming data to stop the delivery of malicious
content, or choosing strong passwords. Detection methods include
inspecting logs or network traffic. Mitigation could include
deploying backups to recover from an attack with minimal disruption.
The endpoint model definitions in sections 2.3 and 2.4 are simple
but the security capabilities of each component may be complex. Each
layer may or may not have a certain spectrum of intrinsic
capabilities and there may be multiple ways to provide add-on and
third-party endpoint security capabilities, allowing complex
interactions between all of these components.
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4.1. Intrinsic versus added security
In terms of security capabilities for each layer of the model, there
are those capabilities that are built-in or intrinsic, and there are
those that are added to the layer through external means.
(A) Intrinsic security capability can be built-into each of the
endpoint model layers
o (1) Hardware
o (2) OS/EE
o (3) Application
(B) Add-on security capability can be
o (4) a component of the hardware
o (5) a component of the OS/EE
o (6) an application by itself
In (A), there is a built-in, 'security by design' approach of the
developer or manufacturers. They often offer a security model and
security capabilities as part of their design.
In (B), a 3rd party is offering an additional security component
which was not necessarily considered when the Hardware, OS/EE or
Application was designed.
With regard to (6), there are many available options for add-on
security capabilities offered by third-parties as applications on a
commercial or open-source basis.
Gartner (see [5] highlights the evolution of endpoint security
towards two directions as shown in [6], [7], and [8].
o Endpoint Protection Platform (EPP) as an integrated security
solution designed to detect and block threats at the device level.
o Endpoint Detection and Response (EDR) as a combination of next
generation tools to provide anomaly detection and alerting, forensic
analysis and endpoint remediation capabilities.
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4.2. Specific Endpoint Security Capabilities
Endpoint security capabilities can be grouped into four broad areas:
o those capabilities that are intrinsic to the endpoint and its
network connectivity
o those that protect against the execution of problematic code
o those that protect against malware installation and execution
o those that protect against weaknesses in applications.
In the following sections, examples of these capabilities are
provided.
4.2.1. Intrinsic Capabilities
o Software updates / patching
o Access Control (RBAC, ABAC, etc.)
o Authentication
o Authorization
o Detailed event logging
4.2.2. Execution protection
o Exploit mitigation (file/memory)
o Tamper protection
o Whitelisting filter by signatures, signed code or other means
o System hardening and lockdown (HIPS, trusted boot, etc.)
4.2.3. Malware protection
o Scanning - on access/on write/scheduled/quick scan (file/memory)
o Reputation-based blocking on files or by ML
o Behavior-based detection - (heuristic based/ML)
o Rootkit and firmware detection
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o Threat intelligence based detection (cloud-based/on premise)
o Static detection - generic, by emulation, by ML, by signature
4.2.4. Attack/Exploit/Application Protection
4.2.4.1. Application protection (browser, messaging clients, social
media, etc.)
o Disinformation Protection (anti-phishing, fake news, anti-spam,
etc.)
o Detection of unintended link location (URL blocklist, etc.)
o Memory exploit mitigation, e.g. browsers
4.2.4.2. Network Protection (local firewall, IDS, IPS and local proxy)
inbound and outbound
o Detection of network manipulation (ARP, DNS, etc.)
o Data Loss Prevention and exfiltration detection (incl. covert
channels)
5. Optimal Properties of an Endpoint Security Solution
It is impossible to provide a complete list of the properties of an
optimal endpoint security solution. The evolution of the threat
landscape ensures that endpoint security solutions will require new
features in the future. However, it is possible to provide a (non-
exhaustive) list of properties - in the spirit of best practices -
for an endpoint security solution.
o find instantly accurate reputation for any file before it gets
executed and block it if needed.
o monitor any behavior on the endpoint, including inbound and
outbound network traffic, learn and identify normal behavior and
detect and block malicious actions, even if the attack is misusing
legitimate clean system tools or hiding with a rootkit.
o patch instantly across all devices/systems/OSes, including virtual
patching, meaning you can patch or shield an application even before
an official patch is released.
o exploit protection methods for all processes where applicable,
e.g. no execute bit (NX), data execution prevention (DEP), address
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space layout randomization (ASLR), Control Flow Integrity Guard
(CFI/CFG), stack canaries, shadow stack, reuse attack protection
(RAP), etc. all of which are methods, which make it very difficult
to successfully run any exploit, even for zero day vulnerabilities.
o detect attempts to re-route data to addresses other than those
which the user intended, e.g. detect incorrectly served DNS entries,
TLS connections to sites with invalid certificates, data that is
being proxied without explicit user consent, etc.
o have an emulator/sandbox/micro virtualization to execute code and
analyse the outcome and perform a roll back of all actions if
needed, e.g. for ransomware.
o allow the endpoint to communicate with the other endpoints in the
local network and globally, to learn from 'the crowd' and
dynamically update rules based on its findings.
o be in constant sync with all other endpoints deployed on a network
and other security solutions, run on any OS, with no delay
(including offline modes and on legacy systems).
o run from the OS/EE when possible.
o run as one of the first process on the OS/EE and protect itself
from any form of unwanted tampering.
o offers a reliable logging that can't be tampered with, even in the
event of system compromise.
o receive updates instantly from a trusted central entity.
6. Case Studies in the Limitations of Endpoint Security Only
The previous section discusses what some of the optimal features of
endpoint security 'system' would be. However, a more realistic view,
based on operational security data would indicate:
o may not be able to run at full capacity due to computational power
limits, battery life, performance, or policies (such as BYOD
restrictions in enterprise networks), etc.
o may not be able to run at full capacity as it slows down
performance too much.
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o will miss some of the malware or attacks, regardless of detection
method used, like signatures, heuristics, machine learning (ML),
artificial intelligence (AI), etc.
o have some level of False Positives (FP).
o not monitoring or logging all activities on the system, e.g. due
to constraints of disk space or when a clean windows tool is being
triggered to do something malicious but the activity is not logged.
Such activity can be logged, but a decision needs to be made if it's
clean or not.
o have its own vulnerabilities or simple instabilities that could be
used to compromise the system.
o be tampered with by the user, e.g. disabled or reconfigured.
o be tampered with by the attacker, e.g. exceptions added or log
files wiped.
In the following section, a number of these limitations are reviewed
in case studies.. Some limitations are absolute, and some
limitations result in a grey area or suboptimality for the endpoint
security solution.
6.1. Unable to put an endpoint security add-on on the UE
We have seen that UEs will vary a lot; by 2022, an estimated 29
billion devices will be connected, with 18 billion of them related
to IoT [9]. Many IoT products lack the capacity to install any
endpoint security capabilities, are unable to update the software,
and it is not possible to force the UE provider to improve or even
offer an intrinsic security capability.
In IoT we find UEs such as medical devices which are limited by
regulation, welding robots that can't be slowed down, smart light
bulbs which are limited by the processing power, etc. There are many
factors influencing whether endpoint security can be added to a UE:
* The UE is simply not powerful enough or the performance hit is too
high.
* Adding your own security will breach the warranty or will
invalidate a certification or a regulation (breach of validity).
* The UE needs to run in real-time and any delay introduced by a
security process might break the process.
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* Some UEs are simply locked by design and the manufacturer does not
provide a security solution (e.g. smart TV, fitness tracker or
personal artificial assistants) see [10], [11].
In the future, a possible research problem would be to find hard
data on the exact proportion of IoT devices that are unable to run
any endpoint security add-on or that have no intrinsic security
built-in.
The other hidden dimension here is the economical aspect. Many
manufacturer are reluctant to invest in IoT device security, because
it can significantly increases the cost of their solution and there
is the perception that they will lose market shares, as customers
are not prepared to pay the extra cost for added security.
6.1.1. Not receiving any updates or functioning patches
The endpoint security system may lack a built-in capability to be
patched or it may be connected to a network that prevents the
process of downloading updates automatically. For example stand-
alone medical systems or industrial systems in isolated network
segments often do not have a communication channel to the Internet.
Even if security updates are received, they typically will only be
periodically updated; hence there will be a window of opportunity
for an attacker, between the time the attack is first used, and the
time the attack is discovered/patched and the patch is deployed.
In addition updates and patches may themselves be malicious by
mistake, or on purpose if not properly authenticated, or if the
source of the updates has malicious intent. This could be part of a
software update supply chain attack or an elaborate attacker
breaking the update process, as for example seen with the Flamer
group (see [12]).
A recent survey found that fewer than 10% of consumer IoT companies
follow vulnerability disclosure guidelines at all, which is regarded
as a basic first step in patching vulnerabilities (see [13]). This
indicates that many IoT devices do not have a defined update process
or may not even create patches for most of the vulnerabilities.
Furthermore some endpoints system may reach the end of their support
period and therefore no longer receive any updates for the OS/EE or
the security solution due to missing licenses. However the systems
may remain in use and become increasingly vulnerable as time goes on
and new attacks are discovered.
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In the following sections, individual examples of attacks on
endpoints unable to provide for their own security are examined. In
each case, the description of the attack follows the format of . . .
6.1.2. Mirai IoT bot
6.1.2.1. Mirai Description 1
| Description | A Mirai bot infecting various IoT devices through
weak passwords over Telnet port TCP 23 and by using various
vulnerabilities, for example the SonicWall GMS XML-RPC Remote Code
Execution Vulnerability (CVE-2018-9866) on TCP port 21009. Once a
device is compromised it will scan for further victims and then
start a DoS attack. |
| Simplified attack process | Compromised device scans network for
multiple open ports, attempts infection through weak password and
exploits, downloads more payload, starts DoS attack. |
| UE | No security tool present on majority of IoT devices, hence no
detection possible. If a rudimentary security solution with limited
capabilities such as outgoing firewall is present on the IoT device
e.g. router, then it might be able to detect the outbound DoS attack
and slow it down. |
| References | [14] }[15] |
6.1.2.2. Mirai Description 2
| Name | Mirai |
| Description | A device infection for participation into a botnet
activity |
| Endpoint Targeted | IoT Devices |
| Attack Surface Categories Involved | Telnet remote access; Weak
default and existing passwords; Code vulnerabilities in exposed
services |
| Attack Surface Examples | Weak passwords over Telnet TCP port 23;
SonicWall GMS XML-RPC Remote Code Execution Vulnerability (CVE-2018-
9866) on TCP port 21009 |
| Attack Objective | Deployment of a custom code or commands on the
device for participation in botnet activities |
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| Attack Category | Botnet Deployment; DDoS |
| Attack Orchestration | Exploit remote access weaknesses on the
device to deploy a bot on the device |
| Mitigation | If a rudimentary security solution with limited
capabilities such as outgoing firewall is present on the IoT device
e.g. router, then it might be able to detect the added bot or the
outbound DoS attack and slow it down |
| Attack Surface Minimisation | Better password management; Uptodate
patching |
| References | [14] [15] |
6.2. Endpoints may not see the malware on the endpoint
6.2.1. LoJax UEFI rootkit
| Description | A device compromised with the LoJax UEFI rootkit,
which is active before the OS/EE is started, hence before the
endpoint security is active. It can pass back a clean 'image' when
the security solution tries to scan the UEFI. Infection can either
happen offline with physical access or through a dropper malware
from the OS/EE. |
| UE | A perfect endpoint security could potentially detect the
installation process if it is done from the OS/EE and not with
physical modification or in the factory. Once the device is
compromised the endpoint security solution can neither detect nor
remove the rootkit. The endpoint solution may detect any of the
exhibited behaviour, for example if the rootkit drops another
malware onto the OS/EE at a later stage. |
| Reference | [16] |
6.2.2. SGX Malware
| Description | Malware can hide in the Intel Software Guard
eXtensions (SGX) enclave chip feature. This is a hardware-isolated
section of the CPU's processing memory. Code running inside the SGX
can use return-oriented programming (ROP) to perform malicious
actions. |
| UE | Since the SGX feature is by design out of reach for the
OS/EE, an endpoint security solution can neither detect nor remove
any injected malware. A perfect endpoint security solution could
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potentially detect the installation process if it is done from the
OS/EE and not with physical modification or in the factory. |
| References | [17] [18] |
6.2.3. AMT Takeover
| Description | A targeted attack group can remotely execute code on
a system through the Intel AMT (Active Management Technology)
vulnerability (CVE-2017-5689) over TCP ports 16992/16993. This
provides full access to the computer, including remote keyboard and
monitor access. The attacker can install malware, modify the system
or steal information. |
| UE | The AMT is accessible even if the PC is turned off. Therefore
any endpoint security software installed on the OS, would not be
able to see this traffic and therefore also not able to detect it. |
| References | [19], [20] |
6.2.4. AMT case study (anonymised)
An enterprise has a data center containing very sensitive data.
Their workstations use a certain Intel chipset which integrates the
AMT feature for remote computer maintenance. AMT is an interface for
hardware management of the workstations, including transmission of
screen content and keyboard and mouse input for remote maintenance.
Communication with the management workstation is implemented by AMT
through the network interface card (NIC) on the motherboard. The
network packets generated in this way are invisible both to the main
processor and thus to the OS running on the workstation. In autumn
of 2015, it became known that some AMT-enabled computers had a flaw
that allowed AMT's remote maintenance component to be activated and
configured by attackers. This also worked when the workstations were
switched off. The leakage of data through this vulnerability is
elusive and difficult to detect. The identified threat situation led
the organization to a new requirement implementing a method that can
reliably detect this and similar vulnerabilities. In particular, the
detection of rootkits and manipulated firmware, and this includes
also (UEFI) BIOS - has also been a focus of their attention.
The method used as a solution, compares the desired data packets
generated by a client operating system - the user, with the data
packets received on the switch port. If more data has been received
on the switch port than was been sent by the operating system - the
user, there is a strong possibility that something bad is happening
- like for example an infection via modified firmware or by rootkit.
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6.2.5. Users bypass the endpoint security
| Description | Endpoint security systems should not interfere with
the normal operation of the endpoint to the extent that users become
frustrated and want to disable them or configure them to disable a
significant fraction of important security capabilities. |
| UE | Add-on endpoint security is now bypassed or disabled by the
user. Unless the endpoint is under monitored management or can
prevent a user from modifying the configuration, then this is
shutting down a significant fraction of the security capabilities. |
| References | [21] |
6.3. Endpoints may miss information leakage attacks
Another aspect that endpoint security has issues in detecting are
information disclosure or leakage attacks, especially on shared
virtual/physical systems.
6.3.1. Meltdown/Specter
The Meltdown/Specter vulnerabilities and all its variants may allow
reading of physical memory belonging to another virtual machine (VM)
on the same physical system. This could reveal passwords,
credentials, certificates etc. The trick is that an attacker can
spin up his own VM on the same physical hardware. As this VM is
controlled by the attacker, they will ensure that there is no
endpoint security that detects the Meltdown exploit code when run.
It is very difficult for the attacked VM to detect the memory read-
outs. For known CPU vulnerabilities there are software patches
available than can be applied. If it is an external service
provider, it might not be in the power of the user to patch the
physical system or to determine if this has been done by the
provider.
6.3.2. Network daemon exploits
Other attack types, which leak memory data from a vulnerable web
server, are quite difficult to detect for an endpoint security. For
example the Heartbleed bug allows anyone on the Internet to read the
memory of the systems protected by the vulnerable versions of the
OpenSSL software. This could lead to credentials or keys being
exposed. An endpoint solution needs to either patch the vulnerable
application or monitor it for any signs of exploitation or data
leakage and prevent the data from being exfiltrated.
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6.3.3. SQL injection attacks
A SQL injection attack is an example of an attack that exploits the
backend logic of an application. Typically, this is a web
application with access to a database. By encoding specific command
characters into the query string, additional SQL commands can be
triggered. A successful attack can lead to the content of the whole
database being exposed to the attacker. There are other similar
attacks that can be grouped together for the purpose of this task,
such as command injection or cross site scripting (XSS). Although
they are different attacks, they all at their core fail at input
filtering and validation, leading to unwanted actions being
performed.
Applications that are vulnerable to SQL injections are very common
and are not restricted to web applications. An endpoint solution
needs to monitor all data entered into possible vulnerable
applications. This should include data received from the network. A
generic pattern matching for standard SQL injection attack strings
can be applied to potentially block some of the attacks. In order to
block all types of SQL injection attacks the endpoint solution
should have some knowledge about the logic of the monitored
application, which helps to determine how normal requests differ
from attacks.
Applications can be analysed at source code level for potential
weaknesses, but dynamically patching is very difficult. See { [22] }
6.3.4. Low and slow data exfiltration
An endpoint security solution can detect low and slow data
exfiltration, for example when interesting data sources are tracked
and access to them is monitored. If the data source is not on the
endpoint itself, e.g. a database in the network, then the received
data needs to be tagged and its further use needs to be tracked. To
make detection difficult, an attacker could decide to use an
exfiltration process that sends only 10 bytes every Sunday to a
legitimate cloud service. If that is not in the normal behavior
pattern, then this anomaly could be detected by the endpoint. If the
process that sends the data or the destination IP address have a bad
reputation, then they could be stopped. Though it is very difficult
to reliably block such an attack and most solutions have a specific
threshold that needs to be exceeded before it is detected as an
anomaly.
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6.4. Suboptimality and gray areas
6.4.1. Stolen credentials
Stolen credentials and misuse of system tools such as RDP, Telnet or
SSH are a valid scenario during attacks. An attacker can use stolen
credentials to remotely log into a system and access data or execute
commands in this context like the legitimate user might do. An
endpoint security solution can restrict access from specific IP
addresses, but this is difficult in a dynamic environment and when
an attacker might have already compromised a trusted device and
misuse it as a stepping stone for lateral movement. The endpoint
could perform additional checks of the source device, such as
verifying installed applications and certain conditions. Again this
will not work in all scenarios, e.g. a hijacked valid device during
lateral movement.
This means that the system will not be able to simply block the
connection if the authentication with the stolen credentials
succeeds. A multi factor authentication (MFA) could limit the use of
stolen credentials, but depending on the system used and the
determination of the attacker they might be able to bypass this
hurdle as well e.g. cloning a SIM card to read text message codes.
As a next step, a solution on the endpoint can monitor the behavior
of the logged in user and determine if it represents expected normal
behavior. Unfortunately, there is the chance for false positives
that might block legitimate actions, hence the rules are usually not
applied too tightly. The system can monitor for suspicious behavior,
similar to malware detection, where every action is carefully
analyzed and all activity is tracked. For example if the SSH user is
adding all files to archives with passwords and then deletes the
original files in the file explorer, then this could result in a
ransomware case scenario. If only a few files are processed per
hour, then this activity will be very difficult for the endpoint to
distinguish from normal activity, in order to flag it as malicious.
The problem of attackers blending in with normal activity is one of
the biggest challenges with so called living off the land attack
methods. The attacker chooses to keep their profile low by not
installing any additional binary files on the system, but instead
misuses legitimate system tools to carry out their malicious intent.
This means that there is no malware file that could be identified
and the detection relies solely on other methods such as behaviour
based monitoring { [23] }.
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If information is shared across multiple endpoints, then each one
could learn from the others and see how many connections came in
from that source, what files were involved and what behavior the
clients exhibited. This crowd wisdom approach would allow blocking
rules to be applied after the first incident across multiple
endpoints.
6.4.2. Zero Day Vulnerability
| Description | An attacker exploits a zero day vulnerability or any
recent vulnerability. |
| UE | In theory this scenario could be handled by the endpoint
security: a) Once the intrinsic security system has been patched,
exploitation of the vulnerability can be prevented. b) The add-on
security with enhanced capabilities or updated methods can detect
and mitigate the vulnerability. It does not necessarily require the
official patch.|
| Challenge | In practice many systems remain vulnerable to a
vulnerability months or even years after a security fix has been
released. Moreover there is a big gap between when a vulnerability
is disclosed and when a security fix is available. Also there is a
big gap between when a security fix is available and when the
security fix is actually applied. A recent study over three years,
examined the patching time of 12 client-side and 112 server-side
applications in enterprise hosts and servers. It took over 6 months
on average to patch 90% of the population across all
vulnerabilities. { [24] }. We note too: "The patching of servers is
overall much worse than the patching of client applications. On
average a server application remains vulnerable for 7.5 months." |
| References | { [25] }{{ [26] } |
6.4.3. Port scan over the network
An infected machine, let's say a Mirai bot on a router, is scanning
a class B network for IP addresses with TCP port 80 open. The
malware can slow it down to 1 IP address per 5 seconds (or any other
threshold) and it can go in randomized order (like for example the
nmap tool does) in order to make it difficult to find a sequential
pattern. To increase detection difficulties, legitimate requests to
existing web servers can be added in at random intervals.
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An endpoint solution might be able to detect this behaviour,
depending on the threshold, but it will be difficult. At some point
the pattern will be similar to browsing the web, so either the
endpoint blocks the bot scanning and also the user from surfing, or
it allows both.
To make it even harder, the attacker can use a botnet that
communicates over peer-to-peer (P2P) or a central command and
control server (C&C) and then distribute the scan load over multiple
hosts. This means each endpoint only scans a subset, let's say 100
IP addresses, but all 1,000 bots scan a total of 100,000 IP
addresses.
This attack is difficult to detect by a reasonable threshold on each
endpoint individually. If the endpoints talk to each other and
exchange information, then a collective decision can be made on the
bigger picture of the bot traffic.
Another option for the endpoint solution is to block the bot malware
from operating on the computer, for example by detecting the
installation, analyzing the behavior of the process or by preventing
the binary from accessing the network. This includes blocking any
form of communication for the process to its C&C server, regardless
of if it is using a P2P network or misusing legitimate system tools
or browsers to communicate with the Internet. Blocking indirect
communication over system tools as part of living off the land
tactics, can be very challenging.
See { [27] }
6.4.4. DDoS attacks
For this example let us consider a botnet of 100,000 compromised
computers and each one sends a burst of traffic to a remote target,
for one second each, alternating in groups. This will generate some
waves of pulse attack traffic. Similar comments can be made about
overall pulsed DDoS attacks { [28] }.
A solution on the endpoint can attempt to detect the outgoing
traffic. If the DoS attack is volume based and the time span of each
pulse is large enough or the repeating frequency for each bot is
high, then detection with thresholds on the endpoint is feasible. It
is different, if it is an application layer DoS attack, where the
logic of the receiving application is targeted, for example with too
many search queries in HTTP GET requests. This would flood the
backend server with intensive search requests, which can result in
the web site no longer being responsive. Such attacks can succeed
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with a low amount of requests being sent, especially if its
distributed over a botnet. This makes it very difficult for a single
endpoint to detect such an ongoing attack, without knowledge from
other endpoints or the network.
Another option for the endpoint solution is to block the bot malware
from operating on the computer, for example by detection the
installation, analyzing the behavior of the process or by preventing
the binary from accessing the network. This includes blocking any
form of communication for the process to its C&C server, regardless
of if it is using a P2P network or misusing legitimate system tools
or browsers to communicate with the Internet. Blocking indirect
communication over system tools as part of living off the land
tactics, can be very challenging.
7. Defense-in-depth from the perspective of protocol design
While endpoint security systems have good capabilities (for
instance, those seen in section 5 above), sometimes it is debatable
and perhaps suboptimal to let the endpoint run the capability alone
or at all. It is generally considered good security practice to
adopt a defense-in-depth approach (see [29]). The Open Web
Application Security Project group (OWASP) describes the concept as
follows:
"The principle of defense-in-depth is that layered security
mechanisms increase security of the system as a whole. If an attack
causes one security mechanism to fail, other mechanisms may still
provide the necessary security to protect the system." (see [29]).
Indeed, there are many other constituencies as per our end-to-end
model that can participate in the defence process: The network, the
infrastructure itself, the platform, the human, the user experience
and in a hybrid of an on premise and cloud approach, an Integrated
Cyber Defence (ICD) of the entire chain.
The simple idea behind the concept is that "every little bit helps".
If the endpoint is not 100% secure itself, the detection chance can
increase with additional security capabilities from other entities.
We acknowledge that there are some case where adding an additional
component to the system may degrade the overall security level by
introducing new weaknesses.
There are various reference articles in the industry highlighting
limitations of endpoint only solutions. For example this quote here,
which talks about multi-tier solutions:
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"There are limitations with any endpoint protection solution,
however, that can limit protection to only the client layer. There
is also a need for security above the client layer, as endpoint
protection products cannot intercept traffic. Vendors will often
sell a multi-tiered solution that enables a network appliance to
assist the endpoint protection client by intercepting traffic
between the attacker and the infected client. Vendors will also sell
solutions that monitor and intercept traffic on internal or external
network segments to protect the enterprise from these threats. A
prime example of the limitations of endpoint protection software is
infection via a phishing attack." [30].
Some sources point out that even the best solution might not get
deployed in the optimal way in a real world scenario as the
environment can be very complex:
"While endpoint security has improved significantly with the
introduction of application whitelisting and other technologies, our
systems and devices are simply too diverse and too interconnected to
ensure that host security can be deployed 100% ubiquitously and 100%
effectively." [31]
On these grounds it is considered a good idea to follow a layered
approach when it comes to security.
"In today's complex threat environment, companies need to adopt a
comprehensive, layered approach to security, which is a challenging
task in such as rapidly evolving, crowded market." [331]
It is important to comprehend the capabilities of endpoint security
solutions in this overall picture of the connected environment,
which includes other systems, networks and various protocols that
are used to interact with these entities. Understanding possible
shortcomings from single layered solutions can help counterbalance
such weaknesses in the architectural concept or the protocol design.
8. Endpoint security from the perspective of protocol design
The previous sections have reviewed two models for endpoints on the
Internet, a review of how endpoints have evolved, an examination of
the features of endpoint security and - finally - a view of how
endpoint security, alone, may not be sufficient to protect endpoints
and users in a evolved Internet. A taxonomy of endpoints is provided
in a companion draft [2]. The evolution has brought a significant
set of new threats and there is evidence that endpoint security is
not enough to protect against those threats.
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This is an observation about operational security, but what does it
mean for protocol design?
8.1. Simplicity of design is important
Protocol design is often informed by attempting to get all possible
use cases addressed in early versions of the protocol design. It is
widely observed that subsequent versions of a protocol - popular or
not - are difficult to achieve. However, simplicity in protocol
design ensures that a protocol will be well-understood at design-
time, it can be modelled and receive a full (and, perhaps formal)
security analysis. The Security Directorate already routinely
reviews protocols in Last Call for their security characteristics -
a practice that should endure. However, making protocol design
decisions that allow for easy, open review helps build confidence in
the security of the underlying design.
It is certain that there will always be unintended consequences in
choices made at protocol design time. However, if the underlying
protocol is not overly complex, those unintended consequences can be
limited. It also make possible modularization or code-reuse allowing
for the reuse of security analysis from one protocol to another.
It is worth noting that implementation is also affected by protocol
design decisions. Complex or poorly defined methods for deployment
of software that implements a protocol means that they are more
likely to be deployed incorrectly or insecurely.
8.2. Diversity in protocol design
Protocol design can include decisions that limit - or, encourage the
limitation - or service diversity. This has market-facing risks but
also has security implications. Where a protocol is too complex to
upgrade or implement, only those with the necessary resources are
likely to benefit from the deployment. Where larger stakeholders
dominate deployment of a particular protocol - because of its
underlying design - the result can be a limited pool of deployments
with potentially smaller numbers of points of failure.
When protocol choices lead to lack of service diversity, this also
increases the risk of shared vulnerabilities among a small set of
providers of service. In this case, the attractiveness of the target
becomes higher as the number of service implementation becomes
lower.
Protocol design should encourage diversity of service provision.
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8.3. Protocol design and failure of intermediaries
The rise of intermediaries has been an important feature of the
evolution of the Internet. In a prior era, it would have been
natural and sufficient to concentrate on deploying security at
endpoints. The end-to-end principle seems to encourage thinking of
building intelligence - and thus, protection - at the edges of the
network.
From previous sections, it is apparent that a strict view of the
end-to-end model no longer applies. Even the model for an endpoint,
as provided in section 2, no longer can support the view of endpoint
protection being for the device or UE. The result is the security of
the endpoint is, in part, dependent on the security of the
middleboxes and intermediary hosts that provide services.
From the point of protocol design, planning for this includes
planning for when those intermediaries are compromised, unavailable
or stop delivering expected services correctly. Protocols that
depend upon intermediaries should clearly adapt to failure modes of
the intermediaries and give choices to endpoint on what actions to
take in the event of third-party failure.
8.4. Protocol evolution
A core message in this draft is that: as the Internet evolves, its
endpoints do as well, and with them the threats they face. Even
ancient protocols are rarely static - especially if they have any
deployment base.
As protocols evolve their designers have to achieve a balance
between interoperability, strictness, agility and extensibility.
Considering this deployment, and altered use case, during design has
the property of making protocol evolution more secure.
Care must be taken, especially in complex protocols where many new
use cases are being account for, in development of the evolution. It
may make the underlying protocol so complex that few are able to
implement it securely. Thus, while the protocol itself may be
secure, it's complexity makes for error in implementation which
leads to operational security problems.
9. Security Considerations
This document is all about security considerations of operational
security for endpoints. In particular it provides a model for
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endpoint security and then discusses why traditional approaches to
endpoint security are no longer sufficient.
10. IANA Considerations
This memo contains no instructions or requests for IANA. The authors
continue to appreciate the efforts of IANA staff in support of the
IETF.
11. Acknowledgements
The original idea for this draft came from another, now expired
draft [33]. The authors of that draft intended a comprehensive
discussion of endpoint security and a clear description of how the
evolution of the Internet made endpoint security - on its own -
insufficient.
The author thanks those previous contributors: Arnaud Taddei, Bret
Jordan, Candid Wueest, Chris Larsen, Andre Engel, Kevin Roundy,
Yugiong Sun, and David Wells.
The author also extends his appreciation to the discussions in the
IAB Activity called model-t where the future of the Internet's
threat landscape has also been discussed.
This document was prepared using 2-Word-v2.0.template.dot.
12. References
12.1. Informative References
[1] Thaler, D. and Tschofenig, H., Pei, M., Tsukamoto, A., " Trust
Execution Environment Protocol ", draft-ietf-teep-protocol-02
(work in progress), April 2020.
[2] McFadden, M., "Evolution of Endpoint Security - A Taxonomy for
Endpoints," draft-mcfadden-opsec-endp-taxonomy-00 (work in
progress), February 2021.
[3] "MITRE CAPEC", <https://capec.mitre.org/data/definitions/3000.html>, n.
d.
[4] "MITRE ATT&CK", <https://attack.mitre.org>, n.d.
[5] Crotty, J., "New Gartner Report Redefines Endpoints Protection for 2018
", January 2018, <https://www.crowdstrike.com/blog/new-gartner-report-
redefines-endpoint-protection-for-2018/>.
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[6] Redscan, ., "EPP and EDR - What's the difference?", June 2018, <https:/
/www.redscan.com/news/epp-vs-edr-whats-the-difference/>.
[7] Hunt, J., "Advantages and Disadvantages of Three Top Endpoint Security
Vendors", n.d., <https://www.adapture.com/blog/evaluating-leading-endpo
int-security-vendors/>.
[8] "IT Pro's Guide to Endpoint Protection", n.d., <https://www.barkly.com/
it-pros-guide-to-endpoint-protection>.
[9] Ericsson, ., "Internet of Things forecast", n.d., <https://www.ericsson
.com/en/mobility-report/internet-of-things-forecast>.
[10] Wueest, C., "How my TV got infected with ransomware and what you can le
arn about it", November 2015, <https://www.symantec.com/connect/blogs/h
ow-my-tv-got-infected-ransomware-and-what-you-can-learn-it>.
[11] Dickson, B., "Millions of smart TVs are vulnerable to hackers", Februar
y 2014, <https://www.dailydot.com/debug/protect-smart-tv/>.
[12] Symantec, ., "W32.Flamer Microsoft Windows Update Man-in-the-Middle", J
une 2012, <https://www.symantec.com/connect/blogs/w32flamer-microsoft-w
indows-update-man-middle>.
[13] Rogers, D., "Handling vulnerabilities as an IoT vendor", December 2018,
<https://www.iotsecurityfoundation.org/less-than-10-of-consumer-iot-com
panies-follow-vulnerability-disclosure-guidelines/>.
[14] Symantec, ., "Mirai, what you need to know about the botnet behind rece
nt major DDoS attacks", October 2016, <https://www.symantec.com/connect
/blogs/mirai-what-you-need-know-about-botnet-behind-recent-major-ddos-a
ttacks>.
[15] Krebs on security, ., "19 Mirai Botnet Authors Avoid Jail Time", Septem
ber 2018, <https://krebsonsecurity.com/tag/mirai-botnet/>.
[16] ESET, ., "LoJax First UEFI rootkit found in the wild, courtesy of the S
ednit group", September 2018, <https://www.welivesecurity.com/2018/09/2
7/lojax-first-uefi-rootkit-found-wild-courtesy-sednit-group/>.
[17] Claburn, T., "Intel SGX safe room easily trashed by white-hat hacking m
arauders Enclave malware demoed", February 2019, <https://www.theregist
er.co.uk/2019/02/12/intel_sgx_hacked/>.
[18] Cimpanu, C., "Researchers hide malware in Intel SGX enclaves", February
2019, <https://www.zdnet.com/article/researchers-hide-malware-in-intel-
sgx-enclaves/>.
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[19] Khandelwal, S., "Explained - How Intel AMT Vulnerability Allows to Hack
Computers Remotely", May 2017, <https://thehackernews.com/2017/05/intel
-amt-vulnerability.html>.
[20] Symantec, ., "Web Attack Intel AMT Privilege Escalation CVE-2017-5689",
2017, <https://www.symantec.com/security_response/attacksignatures/deta
il.jsp?asid=29888>
[21] Smith, K., "9 signs your endpoint security isn't working", May 2017, <h
ttps://securelement.com/9-signs-your-endpoint-security-isnt-working/>.
[22] Cobb, M., "SQL injection detection tools and prevention strategies", No
vember 2009, <https://www.computerweekly.com/tip/SQL-injection-detectio
n-tools-and-prevention-strategies>.
[23] Wueest, C., "Living off the land and fileless attack techniques", July
2017, <https://www.symantec.com/content/dam/symantec/docs/security-cent
er/white-papers/istr-living-off-the-land-and-fileless-attack-techniques
-en.pd>.
[24] Caballero, J., "Mind Your Own Business A Longitudinal Study of Threats
and Vulnerabilities in Enterprises", February 2019, <https://www.ndss-s
ymposium.org/wp-content/uploads/2019/02/ndss2019_03B-1-2_Kotzias_paper.
pdf>
[25] McHugh, J., "Windows of Vulnerability A Case Study Analysis", 2000, <ht
tp://www.cs.colostate.edu/~cs635/Windows_of_Vulnerability.pdf>.
[26] Plattner, B., "Large-Scale Vulnerability Analysis", September 2006, <ht
tp://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.173.3056&rep=rep
1&type=pdf>.
[27] Marinho, R., "Exploring a P2P transient botnet - From Discovery to Enum
eration", July 2017, <https://morphuslabs.com/exploring-a-p2p-transient
-botnet-from-discovery-to-enumeration-e72870354950>.
[28] Seals, T., "Pulse-Wave DDoS Attacks Mark a New Tactics in Q2", October
2017, <https://www.infosecurity-magazine.com/news/pulsewave-ddos-attack
s-mark-q2/>.
[29] UK, GOV., "Secure by Design", February 2019, <https://www.gov.uk/govern
ment/collections/secure-by-design>.
[30] Cullen, T., "Limits of endpoint only", July 2017, <https://www.adapture
.com/blog/evaluating-leading-endpoint-security-vendors/>
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[31] Dix, J., "Layered Security Defenses What layer is most critical network
or endpoint", July 2011, <https://www.networkworld.com/article/2220204/
tech-debates/layered-security-defenses--what-layer-is-most-critical--ne
twork-or-endpoint-.html>.
[32] Hstoday, ., "Layered Approach Critical to Effective Endpoint Protection
", October 2016, <https://www.hstoday.us/channels/federal-state-local/l
ayered-approach-critical-to-effective-endpoint-protection/>.
[33] Taddei, A., et.al., [I-D:draft-taddei-smart-cless-
introduction], "Capabilities and Limitations of an Endpoint-
only Security Solution, July 2020, (expired).
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Appendix A. Operational Experience and Endpoint Security
This appendix attempts to document operational experience related to
endpoint security. The original text in this Appendix comes from
research and experienced from a single security solution provider.
What follows is reporting from that organization.
There are two appaorches to reporting on security incidents that are
based on operational experience. They are:
o the method described in {{MONEYBALL}}
o the anonymised production data of Symantec MSS production for the
past 3 months
The core idea is to consider, based on all the imperfections we
started to list above including the 'grey areas', that cybersecurity
analysts are often presented with suspicious machine activity that
does not conclusively indicate a compromise, resulting in undetected
incidents or costly investigations into the most appropriate remedi
As Managed Security Services Providers (MSSP's) are confronted with
these data quality issues, but also possess a wealth of cross-
product security data that enables innovative solutions, we decided
to use the Symantec MSS service for the past 3 months. The Symantec
MSS service monitors over 100 security products from a wide variety
of security vendors for hundreds of enterprise class customers from
all verticals.
We selected the subset of customers using the service that deploy
both network and endpoint security products to determine which types
of security incidents were most likely to be detected by endpoint
products vs. network products. In doing so, we were particularly
interested in identifying which categories of incidents are detected
by endpoint products and not network products, and vice versa. Thus,
we examined prevalent categories of incidents for which the only
actionable security alerts were predominantly produced by one type
of security product and not the other. To do so, we extracted all
security incidents detected by Symantec MSS on behalf of hundreds of
customers that deploy both network and endpoint security products,
over a three-month period from December 2018 through the end of
February 2019. We acknowledge that some attacks might have been
blocked by the first product and therefore have never been seen by
the next security solution, which influences the final numbers.
With this in mind, we could identify incidents based on:
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| Severity | 4 - Emergency, 3 - Critical, 2 - Warning, 1 -
Informational |
| Incident Category | Malicious Code, Deception Activity, Improper
Usage, Investigation, etc. |
| Incident Type | Trojan Horse Infection, Suspicious DGA Activity,
Suspicious Traffic, Suspicious URL Activity, Backdoor infection,
etc. |
| # network incidents | Amount of network only security incidents |
| # all incidents | What is the total amount of incidents on all
security solutions |
| Percentage | Percentage of network security only incidents |
We ended up with
o Hundreds of thousands of security incidents
o which we could categorize in 275 incident types by category and
severity (triplets Severity-Category-Type)
o out of which we searched how many incidents of each type were
detected by a network security product and missed by deployed
endpoint security products at least 75% of the time or vice versa
A.1. Endpoint only incidents
The categories of incidents that are detected primarily by endpoint
security products are fairly intuitive. They consist primarily of
detections of file-based threats and detection of malicious
behaviors through monitoring of system and network behavior at the
process level. The most prevalent of these behavioral detections
include detections of suspicious URLs based on heuristics and
blacklists of IP addresses or domain names. Since most of these
alerts are not corroborated by network products, it seems probable
that the blacklists associated with network products tend to be more
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focused on attacks while host-based intrusion prevention system
alerts focus more on malware command and control traffic. Most other
behavioral detections at the endpoint provide alerts based on system
behavior that is deemed dangerous and symptomatic of malicious
intent by a malicious or infected process. The highest severity
incidents detected on endpoints are instances of post-compromise
outbound network behavior that are symptomatic of command and
control communications traffic, but these did not show up as being
primarily detected by endpoint products as they are frequently
corroborated by network-based alerts.
A.2. Security incidents detected primarily by network security products
Perhaps less intuitive are the results of examining categories of
security incidents that are detected primarily by network security
products and only rarely corroborated by endpoint security products.
Below we provide details regarding incident categories for which a
network security product produced a detection and for which there
were no actionable endpoint alerts for at least 75% of the incidents
in the category.
In our study we found 32 incident type, category, and severity
triplets of this type. The following categories critical incident
types were reported by MSS customers, and we discuss each in turn in
decreasing order of prevalence:
A.2.1. Unauthorized external vulnerability scans
Perhaps unsurprisingly, unauthorized external attempts to scan
corporate resources for vulnerabilities and other purposes are
detected in large volumes by a broad variety of network-focused
security products. 79% of incidents of this type were detected by
network security products with critical-severity alerts, these
security incident detections are not accompanied by any actionable
endpoint alerts, despite the fact that endpoint security products
are deployed by these enterprises. This category of threats
encompasses a broad variety of attacks, the most prevalent of which
are the following: Horizontal scans, SQL injection attacks, password
disclosure vulnerabilities, directory traversal attacks, and
blacklist hits. Of these categories of detections, horizontal scans
stand out as the category of detection that endpoint-security
products are least likely to detect on their own.
A.2.2. Unauthorized internal vulnerability scans
Unauthorized internal vulnerability scans, though less frequent, are
more alarming, as they are likely to represent possible post-
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compromise activity. We note that the Managed Security Service works
with its customers to maintain lists of devices that are authorized
to perform internal vulnerability scans, and their activity is
reported separately at a lower levels of incident severity. 89% of
detected unauthorized internal vulnerability scans are detected by
network products without any corroborating actionable alerts from
endpoint security products. As compared to unauthorized external
scan incidents, internal hosts that perform vulnerability scans are
far more active and the fraction of alerts that detect horizontal
scans is higher, representing half of the total alerts generated.
Alerts focused on Network-Behavior Anomaly Detection also appear for
internal hosts.
A.2.3. Malware downloads resulting in exposed endpoints
This category of threats is generally detected by network security
appliances. Despite these enterprises being purchasers of endpoint
security products, 76% of the incidents detected by the network
security products do not show a corresponding alert by an endpoint
security product. A broad variety of network appliances contributed
to the detection of a diverse collection of malware samples.
A.2.4. Exploit kit infections
This category of infections represents instances in which the
customer's machines are exposed to exploit kits. These threats were
detected by network appliances that extract suspicious URLs from
network traffic taps and use a combination of sandbox technology and
blacklists to identify websites that deploy a variety of exploit
kits that were not being caught by endpoint security products. In
this three month time period, the most prevalent categories of
exploit kits detected involved redirections to the Magnitude exploit
kit and exploit kits associated with phishing scams and attempts to
expose users to fake Anti-Virus warnings and tools. A breakdown of
the results is included below:
| Severity | 3 - Critical |
| Incident Category | Malicious Code |
| Incident Type | Exploit Kit Infection |
| # network incidents | 26 |
| # all incidents | 26 |
| Percentage | 100% |
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The network security product that detected these incidents produced
the following alerts:
o Advanced Malware Payloads
o Exploit.Kit.FakeAV
o Exploit.Kit.Magnitude
o Exploit.Kit.MagnitudeRedirect
o Exploit.Kit.PhishScams
o HTMLMagnitudeLandingPage
A.2.5. Attacks against servers
In addition to detecting the aforementioned critical security
incident categories, network security devices frequently detect a
broad variety of attacks against servers that usually lack
corroboration at the endpoint. Most server attacks are not matched
by endpoint protection alerts: 62% are unmatched for critical
incidents, and 88% are unmatched as lower severity incidents. This
category of incidents is the most prevalent category of incidents
detected primarily by network products, but they are usually rated
lower in severity than the aforementioned classes of alerts as they
are very commonplace. Even when these alerts are corroborated by
endpoint protection alerts, the endpoint alerts are often low in
severity, as in the case of file-based threats that appear to have
been blocked or successfully cleaned up by an Anti-Virus solution.
The challenge in taking action against server attacks is that it can
be difficult to assess which of these attacks were successful in
causing actual damage, and for this reason, for the fraction of
server attacks that demonstrate corroborating endpoint security
alerts, even if of low severity, should be examined. It is
interesting to note the cooperative role played by both network and
endpoint security devices in these instances.
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Authors' Addresses
Mark McFadden
Internet policy advisors ltd uk
6 Bridge Street
Chepstow, Wales NP16 5EY
United Kingdom
Phone: +44 2921 25 3649
Email: mark@internetpolicyadvisors.com
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