Intrusion Prevention | Vulnerability
Management
To improve the effectiveness of their security infrastructure, many organizations
have deployed a network intrusion prevention system (IPS). Historically, however,
this technology has been somewhat of a paradox. Although it can reliably detect
and prevent a wide range of network-borne threats, it has been criticized for
the “noise” or false positives it creates and the corresponding
effort required to separate significant events from the potentially overwhelming
amount of insignificant events.
Furthermore, even though security administrators
understand the recommendation to tune their detection systems for the actual
computing environment that is being protected, this is viewed as a signifi can't
operational burden.
The result is that organizations typically accept a compromise,
settling for an alternative that is less effective from a security perspective
in exchange for reduced administrative effort—such as operating with a
vastly reduced, generic set of inspection rules.
We recommend:
Product:
Sourcefire IPS Fundamentally, the goal with intrusion prevention
technology is to stop an attack as it is occurring. Doing so depends on detecting
specific events, having sufficient confidence that those events indeed correspond
to an attack, and engaging a mechanism to actually stop the flow of associated
communications traffic. Knowing which events to detect in the first place is
instrumental to minimizing the occurrence of false negatives, and is why a leading
IPS should incorporate multiple techniques, including exploit-based rules, vulnerability-based
rules, protocol anomaly rules, and heuristics (i.e., root-cause analysis rules).
Of course, minimizing false positives is absolutely critical, too, which is
why a leading IPS should also analyze a wealth of contextual information to
further qualify the nature and impact of what is being detected.
Sourcefire’s
Adaptive IPS solution addresses an organization’s need for better efficiency
and effectiveness by significantly reducing the number of actionable security
events and sharply reducing or eliminating the manual effort required to tune
Sourcefire’s IPS. The Adaptive IPS feature set consists of several components,
including impact flags, RNA-Recommended Rules, adaptive traffic profiles, non-standard
port handling, and contextually aware engine—all of which work together to ensure
that the Sourcefire IPS™ prioritizes and processes trafficwithout introducing
noise, without blocking legitimate traffic, and without missing critical attacks.

Sourcefire fully supports a Defense-in-Depth intrusion prevention strategy
by allowing Sourcefire 3D Sensors to be positioned at the perimeter, in the
DMZ, in the core, and at critical internal network segments. Sourcefire Defense
Center orchestrates all event aggregation, analysis, and IPS policy management.
Features | Benefits
(Click on each feature to find out more)
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Impact
Flags
Sourcefire RNA™ (Real-time
Network Awareness) leverages a vulnerability database to generate a list of
an asset’s potential vulnerabilities. RNA uses this vulnerability data
to make its impact analysis more accurate.
The Sourcefire Defense Center™,
a highly customizable central management console that provides event aggregation,
asset monitoring, and Sourcefire 3D™ Sensor management, can correlate
security event data with a target’s operating system, services, applications,
and potential vulnerabilities in real time.
By comparing attacks to the assets
of the hosts under attack, the Sourcefire 3D System can assign an “impact”
value to the attack and visually represent this impact with a prioritized
impact flag on the Defense Center dashboard.
By determining the relevance
and impact of each intrusion attack on your network, actionable events are
typically reduced by 99% or more, and security analysts can focus their attention
only on those events that matter most.
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RNA-Recommended Rules
The RNA-Recommended Rules (RRR) feature
leverages the power of Sourcefi re RNA to recommend a set of IPS rules for
a user’s particular network environment. From a functional perspective,
RRR involves three
steps.
First, RNA establishes a profile for a given network, identifying all
hosts, the operating systems (OSes) and services they are running, the ports
they are using to communicate, and the vulnerabilities to which they are potentially
susceptible.
Next, this inventory is compared to the rule set for the 3D Sensor(s) with
IPS protecting the profiled network. The result is a set of recommendations
for rules that should be added or removed from this rule set. For example,
a profile indicating the presence of Linux-based hosts would result in the
recommendation to add “missing” Linux-oriented rules to a 3D Sensor
configuration that did not already have some (or all) of them in place. Finally,
security administrators can choose to accept the recommendations as is or
modify them as desired.
To aid this step, recommended rules are conveniently
organized by category (e.g., OS, service, threat type), and can be selected
individually, by category, or all at once. Furthermore, exceptions can be
configured to suppress unwanted recommendations from recurring in the future.
RNA-Recommended Rules can provide semiautomated IPS tuning as users have the
opportunity to review changes and intervene in the tuning process.
An additional
mode allows RRR to make fully automated tuning decisions at scheduled intervals
without human intervention. The balance of the Adaptive IPS features typically
impact only certain portions of the 3D Sensor configuration (e.g., the subset
of rules that deal with host OSes). Administrators have complete control of
whether, and to a certain extent how, these features are implemented.
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Adaptive Traffic Profiles
Most IPSes are configured to inspect
segmented and fragmented traffic from the viewpoint of a singleoperating system
type. Given this limitation, the potential exists for a clever hacker to circumvent
an IPS’ detection engine. But by modeling segmented andfragmented traffi
c in the same manner in which the host operating system would see it, the
potential for circumventing a Sourcefire IPS is greatly reduced.
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Non-Standard Port Handling
The relationship between certain
services and ports is based on convention. Nothing precludes the use of non-standard
ports (e.g., running HTTP on TCP 8080 instead of TCP 80). In fact, some organizations
purposely take advantage of non-standard ports for management or security
reasons. Alternately, hackers and various user-centric applications (e.g.,
file sharing, IM) will often use non-standard ports to hide their activities.
Sourcefire’s non-standard port handling capability automatically accounts
for such scenarios. This is accomplished by dynamically applying the appropriate
rules for a given session based on input from RNA that identifies the actual
relationship between ports and services for the associated hosts. The net
result is that administrators do not need to manually configure rules for
known cases where services are running on non-standard ports.
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Contextually Aware Engine
Sourcefire is moving toward allowing
RNA Recommended Rules to operate fully dynamically. Sensor rule sets will
be dynamically modified in real time to correspond to the network and host
profiles that are seen in a customer’s environment.
The contextually
aware engine feature will include:
• The RNA-driven automated population/definition of variables (e.g.,
$HTTP_SERVERS) that control the invocation of various 3D Sensor preprocessors.
• The ability to recommend rules and dynamically adjust 3D Sensor confi
gurations based on data and attributes obtained from external tools (e.g.,
vulnerability scanners, patch management systems) via the Sourcefi re Host
Input API.
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