Cisco Secure Access Control System (ACS) contains a vulnerability that could allow an unauthenticated, remote attacker to bypass TACACS+ based authentication services offered by the affected application.
The vulnerability is due to improper validation of user-supplied input processed by the affected software. An unauthenticated, remote attacker could exploit this vulnerability by sending a special sequence of characters when prompted for a targeted user's password. Successful exploitation could allow the attacker to gain unauthorized access to any system that uses TACACS+ and relies on the authentication service provided by the affected software in the networking environment.
Cisco has confirmed this vulnerability and software updates are available.
A successful exploit requires an attacker to know a valid username stored in the LDAP external identity store. If valid usernames have been compromised, the attacker can impersonate only those users. Administrators may consider using role-based access controls (RBAC) for users in the environment to help protect network resources in the event of a successful exploit. In addition, an attacker would likely need access to an internal, trusted network in which a targeted device may reside, decreasing the likelihood of a successful exploit.
Cisco indicates through the CVSS score that functional exploit code exists; however, the code is not known to be publicly available.
Cisco has released a security advisory for Cisco bug ID CSCuc65634 at the following link: cisco-sa-20121107-acs
Administrators are advised to apply the appropriate updates.
Administrators may consider disabling anonymous binding on the LDAP external identity store or use a different Active Directory to help prevent exploitation of this vulnerability if these options are possible in the production environment.
Administrators are advised to monitor affected systems.
Cisco customers with active contracts can obtain updates through the Software Center at the following link: Cisco. Cisco customers without contracts can obtain upgrades by contacting the Cisco Technical Assistance Center at 1-800-553-2447 or 1-408-526-7209 or via e-mail at firstname.lastname@example.org.
The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.
To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.
Version Description Section Status Date 1.0 Initial Release NA Final 2012-Nov-07
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