Advisory ID: cisco-sa-20041111-csa
For Public Release 2004 November 11 16:00 UTC (GMT)
Cisco Security Agent (CSA) provides threat protection for server and
desktop computing systems, also known as endpoints. It identifies and prevents
malicious behavior, thereby eliminating known and unknown security risks.
A vulnerability exists in which a properly timed buffer overflow
attack may evade the protections offered by CSA. The system under attack must
contain an unpatched underlying vulnerability in system software that CSA is
configured to protect. Another prerequisite for the attack is that a user must
be interactively logged in during the attack.
This advisory is posted at
Cisco is making patches available for CSA versions 4.0 free of charge,
to correct the problem.
This section provides details on affected products.
The following products are affected:
Cisco Security Agent versions up to and excluding 4.0.3 build 728
Cisco Security Agent 3.x versions
Okena Stormwatch 3.x versions
Cisco Security Agent for CallManager versions up to and excluding
4.0.3 build 728
Determining the version of the CSA client
To determine which version of CSA is running on client machines simply
right click on the CSA icon in the task bar. On the pop-up menu, selecting
About ... will display the version number of the agent.
Determining the version on the CSA Management
To determine which version of CSA you are running:
Log on to the Management console for Cisco Security Agent on your
Select VPN/Security Management Solution > Management
Center > Security Agents, and then click the Security
This will launch the Management Center for Cisco Security
Agents. Within the browser window, locate the tab in the center marked
Help and click on the sub-item labeled About.
The version of the Cisco Security Agents should show up in a pop-up window
containing text similar to Management Center for Cisco Security Agents
V4.0-1 build 540
No other Cisco products are currently known to be affected by these
CSA versions prior to 22.214.171.1248 contain a vulnerability in the buffer
overflow handling code allowing for the evasion of the protections offered by
CSA. The evasion is timing dependent, where the second of two closely spaced
overflow attacks is not processed by CSA.
In a vulnerable release a buffer overflow will trigger the Overflow
heuristic, generating a query to the user. This query has a countdown timer of
5 minutes after which the default action of "Terminate" is taken in the event
that the user does not make a selection. A second or subsequent buffer overflow
attack that is received during this countdown period will not be trapped by
The result is that a sequence of two buffer overflow attacks in quick
succession can result in the second bypassing CSA protection. If the attack is
targeted at a vulnerable unpatched system process privileged access may result.
Agents prior to 126.96.36.1998 are not affected if a user is not logged in
or if the hidden GUI option is in effect. Under these circumstances the agent
knows that there is no user to respond to a query message. Because of this, the
agent immediately takes the default action to terminate the process thus
preventing the opportunity to evade the protection provided by CSA.
This has been documented in Cisco Bug ID
Cisco has provided scores for the vulnerabilities in this advisory based on the Common Vulnerability Scoring System (CVSS). The CVSS scoring in this Security Advisory is done in accordance with CVSS version 2.0.
CVSS is a standards-based scoring method that conveys vulnerability severity and helps determine urgency and priority of response.
Cisco has provided a base and temporal score. Customers can then compute environmental scores to assist in determining the impact of the vulnerability in individual networks.
Cisco has provided an FAQ to answer additional questions regarding CVSS at
Cisco has also provided a CVSS calculator to help compute the environmental impact for individual networks at
The integrity of the system which CSA is protecting may be compromised
via privileged access which may be gained if patches for underlying system
software vulnerabilities have not been applied.
Environments in which CSA is being used should ensure that they are
188.8.131.528 or later with a minimum of the default desktop or default
server policy enabled.
Customers running Cisco Security Agent for CallManager should ensure
that they are running version
CiscoCM-CSA-184.108.40.2068-1.1.9 or later.
Placing the agents into hidden user interface mode will cause agents
to defeat this attack technique. This is configurable via the CSA Management
Console by selecting No user interaction in all applicable
groups for Microsoft Windows clients.
Cisco has made free software available to address this vulnerability
for affected customers. Prior to deploying software, customers should consult
their maintenance provider or check the software for feature set compatibility
and known issues specific to their environment.
Customers may only install and expect support for the feature sets they
have purchased. By installing, downloading, accessing or otherwise using such
software upgrades, customers agree to be bound by the terms of Cisco's software
license terms found at
or as otherwise set forth at Cisco.com Downloads at
Do not contact either "email@example.com" or "firstname.lastname@example.org"
for software upgrades.
Customers with contracts should obtain upgraded software through their
regular update channels. For most customers, this means that upgrades should be
obtained through the Software Center on Cisco's worldwide website at
Customers whose Cisco products are provided or maintained through prior
or existing agreement with third-party support organizations such as Cisco
Partners, authorized resellers, or service providers should contact that
support organization for guidance and assistance with the appropriate course of
action in regards to this advisory.
The effectiveness of any workaround or fix is dependent on specific
customer situations such as product mix, network topology, traffic behavior,
and organizational mission. Due to the variety of affected products and
releases, customers should consult with their service provider or support
organization to ensure any applied workaround or fix is the most appropriate
for use in the intended network before it is deployed.
Customers who purchase direct from Cisco but who do not hold a Cisco
service contract and customers who purchase through third-party vendors but are unsuccessful in obtaining fixed software through their point of sale should obtain software patches and bug fixes by contacting the Cisco Technical Assistance Center (TAC). TAC
contacts are as follows.
+1 800 553 2447 (toll free from within North America)
+1 408 526 7209 (toll call from anywhere in the world)
Have your product serial number available and provide the URL of this notice as evidence of entitlement to a software patch or bug fix. Customers without service contracts should request a software patch or bug fix through the TAC.
for additional TAC contact information, including special localized telephone
numbers and instructions and e-mail addresses for use in various
The Cisco PSIRT is aware of discussion of this vulnerability in a
Customers running CSA should be aware that exploits do exist which
could be used to exploit unpatched system software on machines where vulnerable
versions of CSA are running.
THIS DOCUMENT IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. YOUR USE OF THE INFORMATION ON THE DOCUMENT OR MATERIALS LINKED FROM THE DOCUMENT IS AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS DOCUMENT AT ANY TIME.
A stand-alone copy or Paraphrase of the text of this document that omits the distribution URL in the following section is an uncontrolled copy, and may lack important information or contain factual errors.
This advisory is posted on Cisco's worldwide website at
In addition to worldwide web posting, a text version of this notice is
clear-signed with the Cisco PSIRT PGP key and is posted to the following e-mail
and Usenet news recipients.
email@example.com (includes CERT/CC)
Future updates of this advisory, if any, will be placed on Cisco's
worldwide website, but may or may not be actively announced on mailing lists or
newsgroups. Users concerned about this problem are encouraged to check the
above URL for any updates.
Corrected URL in Summary section.
Updated affected products and fixed software to include CSA
agent fix on Cisco CallManager.
Initial public release.