Advisory ID: cisco-sa-20020403-acs-win-web
For Public Release 2002 April 3 16:00 UTC (GMT)
Cisco Secure Access Control Server (ACS) for Windows contains two
vulnerabilities. One vulnerability can lead to the execution of an arbitrary
code on an ACS server, and the second can lead to an unauthorized disclosure of
information. A patch is available for both vulnerabilities.
Cisco Secure ACS for Unix is not vulnerable. No other Cisco product is
There is no direct workaround for the vulnerabilities, but it is
possible to mitigate them to a great extent. See the
Workarounds section for details.
This advisory is available at
This section provides details on affected products.
The affected product is Cisco Secure Access Control Server for Windows;
all releases up to and including 2.6.x and ACS 3.0.1 (build 40) are affected.
Cisco Secure ACS for Unix is not affected.
No other Cisco products are currently known to be affected by these
There are two different vulnerabilities, as described by the Bug IDs
below. The first can lead to execution of an arbitrary code; the second can be
used to reveal customer data.
Bug IDs CSCdx17622 and CSCdx17683 -- By connecting
to port 2002 and sending a crafted URL, it is possible to, in a less severe
case, kill the CSADMIN module or, in a severe case, to execute an arbitrary
user-supplied code. The functionality of authentication, authorization, and
accounting (AAA) is not affected by termination of the CSADMIN module. This
means that users will be able to authenticate normally. Only the administration
function will be affected. Port 2002 is used by the CSADMIN module for remote
By providing a URL containing formatting symbols (for example, %s,
%p), it is possible to execute a user-provided code. This technique is
described in the following article:
Bug IDs CSCdx17689 and CSCdx17698 -- By using
"..\.." in the URL it is possible to access data in any directory outside the
Web root directory but on the same hard disk or disk partition. With this
technique it is possible to access only the following file types: html, htm,
class, jpg, jpeg or gif.
Please note that an attacker must know the exact location and file
name. It is not possible to browse a directory this way.
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
By exploiting the format vulnerability, an attacker may execute
arbitrary code on the machine. This code will be executed in the same context
as the CSADMIN process, and that is as administrator. Executing arbitrary code
will lead to a total compromise of the machine.
By exploiting the directory traversal vulnerability, an attacker can
gain unauthorized access to information in the following file types: html, htm,
class, jpg, jpeg or gif. The main issue may be html files with hardcoded
passwords or other sensitive information.
Both vulnerabilities are fixed by the patched CSAdmin.exe files
available at http://www.cisco.com/pcgi-bin/tablebuild.pl/cs-acs-win
. The file names are CSAdmin-patch-2.6-4-4.zip and
CSAdmin-patch-3.0-1-40.zip. These patches must be applied only
to releases 2.6(4.4) and 3.0.1 (build 40). If you are running any other
release, you should open a case with the Cisco Technical
Assistance Center (TAC) to receive a free upgrade. After upgrading to
release 2.6(4.4) or 3.0.1 (build 40), you should apply the patches.
Note: To download these patches, you must be a
user and you must be logged in. Unregistered users should refer to the
instructions in the Obtaining Fixed Software
To install the patch, follow the procedure below while logged in as
Manually stop the CSAdmin service.
Rename the <ACS-DIR>/CSAdmin/CSAdmin.exe file
Copy the patched CSAdmin.exe to <ACS-DIR>/CSAdmin.
Manually start the CSAdmin service.
There are no direct workarounds for these vulnerabilities. However, by
exercising the standard best practices, it is possible to significantly
mitigate both issues. These practices are:
Block all unnecessary traffic on the outer network edge. This
includes private IP address space (10.0.0.0, for example) and spoofed packets.
This can be accomplished using routers or firewalls. For instruction on how to
accomplish this with Cisco routers, please consult documents at
Separate critical internal infrastructure from the rest of your
We strongly recommend that these practices are also followed when
deploying Cisco ACS for Unix, even though it is not vulnerable to the mentioned
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 "firstname.lastname@example.org" or "email@example.com"
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
Both vulnerabilities were reported by Jonas Ländin and Patrik Karlsson
from iXsecurity. Cisco PSIRT was made aware that an exploit program for the
format vulnerability exists. This exploit is not thought to be released to the
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In addition to Worldwide Web posting, a text version of this notice is
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Future updates of this advisory, if any, will be placed on Cisco's
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newsgroups. Users concerned about this problem are encouraged to check the
above URL for any updates.
Updates made to Affected Products, and Software Versions and
Initial Public Release