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The Cisco PSIRT has posted a public response to a vulnerability made
public by a researcher on multiple public mailing lists.
This is the Cisco PSIRT response to the statements made by Darren
Bounds in his advisory: Cisco Secure ACS Weak Session Management
Vulnerability. The original email/advisory is available at
This issue is being tracked by Cisco Bug IDs CSCse26754 and
The attacks described in the report take advantage of a weakness in
the default configuration of the Cisco ACS. Cisco is investigating
this issue and further detail will be added to the Cisco Security
Response as it becomes available.
Cisco's statement and further information are available on the Cisco
public website at
Contact psirt (at) cisco (dot) com [email concealed] with any questions regarding this issue.
On Fri, Jun 23, 2006 at 09:18:51AM -0400, Darren Bounds wrote:
> Cisco Secure ACS Weak Session Management Vulnerability
> June 23, 2006
> Product Overview:
> Cisco Secure Access Control Server (ACS) provides a centralized
> identity networking solution and simplified user management experience
> across all Cisco devices and security management applications.
> Cisco Secure ACS is a major component of Cisco trust and identity
> networking security solutions. It extends access security by combining
> authentication, user and administrator access, and policy control from
> a centralized identity networking framework, thereby allowing greater
> flexibility and mobility, increased security, and user productivity
> Vulnerability Details:
> A vulnerability has been identified in the Cisco Secure ACS session
> management architecture which could be exploited by an attacker to
> obtain full administrative access to the web interface and thus all
> managed assets (routers, switches, 802.1x authenticated networks,
> By default, the Cisco Secure ACS web administration login page runs on
> TCP port 2002. Upon successful authentication, the client is then
> redirected to a dynamicand unique HTTP server port between 1024 and
> 65535. Once authenticated, ACS relies solely upon the port and the
> client IP address to validate the session.
> Clearly one can think of many somewhat trivial techniques for
> acquiring the necessary IP address or senarios where the attacker may
> already share the same source IP as the administrator (proxies, NATing
> devices). Now it's merely a matter of identifying the port allocated
> for the administrative interface. This is easily accomplished as ACS
> follows a simple incrementation process for port allocation.
> Affected Versions:
> Cisco Secure ACS 4.x for Windows
> Legacy versions may also be affected.
> Configure ACLs within Cisco Secure ACS to restrict access to the web
> interface from only 'secure' network address space.
> Cisco has confirmed this vulnerability and is working on a patch.
> Thank you,
> Darren Bounds
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