Cisco Security Advisory
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AV:N/AC:L/Au:S/C:P/I:N/A:N/E:F/RL:OF/RC:C
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A vulnerability in the authentication code of Cisco ASA Software could allow an authenticated, remote attacker to access resources of a VPN tunnel group.
The vulnerability is due to improper implementation of the tunnel group selection when a user authenticates to the remote access VPN via the challenge-response mechanism. This vulnerability may affect Cisco ASA configured to authenticate remote access VPN users via LDAP, RADIUS, TACACS+, and RSA if a challenge-response is needed for authentication. Cisco ASA Software configured for Clientless or AnyConnect SSL VPN is affected by this vulnerability.
An attacker could exploit this vulnerability by crafting a response to the Cisco ASA with a different tunnel group parameter. A successful exploit could allow the attacker to bypass the tunnel group restriction and authenticate to a different tunnel group than the one selected during the authentication phase. This could result in accessing a different set of resources.
Cisco has confirmed the vulnerability in a security notice and released software updates.
To exploit this vulnerability, an attacker must authenticate to the targeted device. This requirement would likely decrease the possibility 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.
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Customers are advised to consult Cisco bug ID CSCtz48533 for a complete list of affected product versions.
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Administrators are advised to apply the appropriate updates.
Administrators are advised to allow only trusted users to have network access.
Administrators may consider using IP-based access control lists (ACLs) to allow only trusted systems to access the affected systems.
Administrators are advised to monitor affected systems.
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Cisco customers with active contracts should contact their Cisco support team for assistance in upgrading to a software version that includes fixes for this vulnerability. Cisco customers without contracts may contact the Cisco Technical Assistance Center at 1-800-553-2447 or 1-408-526-7209 or via email at tac@cisco.com for assistance.
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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.
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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.
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Show LessVersion Description Section Status Date 1.0 Initial Release NA Final 2015-Feb-16
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