Marsa Rayani Maryam Shahpasand Ali Falsafi
• CSIDS definition
• CSIDS components
• CSIDS features
• CSIDS Platforms
• Cisco Security Agent
• CSIDS VS. Snort
Cisco security experts believe that
The most effective intrusion detection strategy is to
implement both host-based and network-based IDS.
Typically, most organizations implement network-based
IDS first, because it’s effective against attacks originating
externally. Adding host-based IDS further enhances
protection from attack, especially from attacks that are
generated from internal sources.
To achieve these elements, Cisco implements a
line of IDS products that can be integrated into
• current network routers
• deployed as separate IDS appliances
• run as software applications on management
• Cisco Secure IDS is a network-based intrusion
detection system that uses a signature database
to trigger intrusion alarms
The major components are:
2. Configuration Manager
3. Event Manager
1. Sensor : This performs real-time monitoring
of network traffic, searching for patterns that
could represent an attack.
Performance of the Sensor when it detects an
Shun (shunning) refers to the complete blocking
of any traffic from the offending host or subnet
Log (logging) refers to both attack event alarms
and whole suspicious IP session logs
Shun + log
TCP connection reset
TCP connection reset + shun
TCP connection reset + log
TCP connection reset + shun + log
2. Configuration manager :
The configuration manager provides
configuration management for the sensor
pushing configuration and policy settings to the
The configuration manager may be co-located with the sensor
(typical for smaller sensor deployments) or may be
separately located at a central location (typical for larger
3. Event manager :
The event manager is used to
collect events generated by sensors.
Cisco Secure IDS event management platforms include a
Network Security Database (NSDB), which includes detailed
information about each attack that is detected by a sensor.
This information provides analysis support for security
administrators who must decipher and respond to detected
Cisco Secure IDS sensors have extremely limited event
management capabilities; hence the event manager is
always separate from the sensor.
4. Software: Cisco Secure IDS (CSIDS) isn’t just
a set of hardware components—it also includes
software that has evolved over years.
Communication between Sensor and
To communicate messages between the management
platform and the sensor platform, Cisco Secure IDS
uses a proprietary protocol called the PostOffice
This protocol provides numerous necessary features,
such as the following:
• Fault tolerance
Cisco Secure IDS Features
Cisco offers a rich IDS product set that is part of Cisco’s
SAFE enterprise security blueprint. Cisco Secure IDS has
many features that let you effectively detect and respond
to security threats against your network. It provides the
following fundamental capabilities:
1. Alarm display and logging
2. Intrusion response
3. Remote sensor configuration and management
These features are discussed in the following sections.
1. Alarm Display and Logging
When a sensor detects an attack, it sends an alarm to the
event management platform. On the event management
platform, a graphical user interface (GUI) displays these
alarms in real time, color-coding each alarm based on its
severity. This display provides a quick indication that an
attack has occurred and how dangerous the attack is.
The sensor can also log more detailed alarm information
in a local text-based log file, which allows for in-depth
analysis of attack data and the use of custom scripts to
present alarm data specific to your requirements.
2. Intrusion Response
The Cisco Secure IDS sensor can directly respond
to an attack using one or more of the following
I. TCP reset
II. IP blocking
III. IP logging
I. TCP reset:
The TCP reset response is available only for TCP-
based attacks. It’s implemented by the sensor
sending a TCP reset packet to the host that is
being attacked (the target). This causes the
attacked system to close the connection,
destroying any processes and memory
associated with the connection.
II. IP blocking
The IP blocking response (also known as
shunning) allows a sensor to apply an access
control list (ACL) to a perimeter router interface,
blocking IP connectivity from an attacking
You can also manually block a host or network
from the sensor management platform if you see
any suspicious activity
III. IP logging
When a sensor detects an attack, an alarm is generated
and forwarded to the event management platform. The
IP logging response allows a sensor to write alarm
information to a local log file as well. The information
written to the log file contains much more information
than is sent to the event management platform, so you
can use this option to provide detailed analysis of
3. Remote Sensor Configuration and
• Cisco Secure IDS sensor management platforms let you
centrally manage and monitor multiple sensors located
throughout your network.
• All sensor-related configurations are stored on a
configuration management platform.
• configuration management platform is responsible for
pushing these configurations out to each sensor.
• Configuration attributes include the types of intrusive
activity (signatures) that each sensor should monitor.
Cisco Secure IDS also includes
• an Active Updates feature, which allows customers
to subscribe to regular e-mail notifications
generated by the Cisco Countermeasures Research
• download new signature updates to a central
location on the network, and then have multiple
sensors automatically update their signature
databases on a regular basis.
• Customize signatures: you create your own
signatures that can detect some new attack. This
functionality is provided by a complete signature
language, which is similar to a scripting language,
providing a powerful tool for customization.
Cisco Secure Sensor Platforms
• The sensor platform is the most critical
component of Cisco Secure IDS, because it
detects, responds to, and reports intrusion
activity to the sensor management platform.
• Each sensor is a hardware appliance that has
been secured for the environment it works in,
optimized for performance, and designed for
ease of maintenance.
• The sensor uses an extensive signature database
that allows it to capture security attacks in
realtime from large amounts of IP traffic.
• Sensor possesses packet-reassembly features
that prevent IDS bypass techniques.
• Once an attack is detected, the sensor sends an
alarm to an event management platform and can
optionally place that alarm information in a local
• The sensor can also automatically reset a TCP-
based connection that is associated with the
attack and/or block the source IP address of the
Cisco produces three main sensor platforms
dedicated to IDS:
• 4200 series sensors
• Catalyst 6000/6500 IDS module (IDSM)
• Cisco 2600/3600/3700 IDS network modules
All of these sensor platforms are passive
sensors, in that they passively monitor network
traffic traversing one or more segments for
intrusive activity. Each of these sensors contains
I. Command-and-control interface
I. Command-and-control interface
• provides a management interface for the
• The command-and-control interface allows the
sensor to be managed via TCP/IP.
• lets the sensor send alarms to the event
• The command-and-control interface is the only
interface that contains an IP address.
II. Monitoring interface
• The monitoring interface operates in
promiscuous mode, capturing all traffic on the
attached segment and passing it to the IDS
application for analysis.
• The monitoring interface doesn’t have an IP
• ensuring that the sensor can be placed on an
insecure segment and not be subjected to an
Cisco Security Agent
• The Cisco Security Agent consists of server and
• The security agent resides between the operating
system kernel and applications.
• enabling visibility of all system calls to memory, file,
network, Registry, and COM object resources.
• Cisco Security Agent is an example of an anomaly-
based intrusion detection system.
• It is useful for detecting new attacks that are often
impossible to detect with signature-based intrusion
detection systems such as Cisco Secure IDS sensors
• The Cisco Security Agent provides a variety of
features that ensure that critical systems and
applications are protected from attacks. It’s
designed to detect known and unknown attacks
based on the following intrusive activities:
Probing relates to the activities associated
with reconnaissance being performed against
the host or an attempt to break into a host by
guessing security information. The following are
some of the probe attacks that the Cisco Security
Password and username guessing
Penetration refers to the process of gaining
unauthorized access to processes running and/or
data stored on the target system. The Cisco Security
Agent can detect a possible attack based on events
that indicate the host is in the process of being
compromised or penetrated. The following are some
of the events related to penetration attacks that the
Cisco Security Agent detects:
Persistence refers to events that result from a
successful attack and subsequent infection of a
host system. The following are some of the events
that indicate that a system has been compromised
and that some form of unauthorized action,
application, or service is present:
Security settings modification
Installation of new services
Propagation refers to the automatic self-
replication of an attack to other systems after an
initial target system has been infected. There are
some of the events related to propagation that the
Cisco Security Agent detects:
E-mail copies of the attack
Web and FTP connections
Internet Relay Chat (IRC) connections
Propagation via file shares
Paralyzing refers to the complete or partial
removal of the availability and responsiveness of
computing resources on a target system. The
following are some of the events related to system
paralysis that the Cisco Security Agent detects:
File modification and deletion
Denial of service
Stealing of sensitive/confidential information
1. Accurate attack detection
2. Intelligent attack investigation
3. Ease of security management
4. Flexible deployment options for all network design
models and topologies
5. you can create your own signatures that can detect
some new attack.
6. combines leading Cisco security solutions with
a rich ecosystem of complementary programs,
products, partners and services.
7. Focuses on large businesses
8. Assumes a security policy
• Black box design, you’ll have no idea why it does
anything that it does.
• Closed signature language, you have no ability to
see what or how they’re trying to detect anything.
• Difficult to install.
• Difficult to administer
CSIDS VS Snort
Battle of Open Source VS Commercial!
• Snort has a better GUI.
• Snort biggest advantage is COST.
• CSIDS is better at both IP fragment and TCP
• CSIDS has an excellent support and services.
• For small environments where funds are very
limited, snort is probably the better solution.
• For large enterprises, Cisco would probably be
the better choice.
• CCSP Complete study book by Cisco