Cisco Adaptive Security Appliance Software contains a vulnerability that could allow an unauthenticated, remote attacker to bypass security restrictions and gain unauthorized access to a device. Updates are available.
A vulnerability in the code for SSL certificate validation of the Cisco ASA Software could allow an unauthenticated, remote attacker to bypass the certificate authentication.
The vulnerability is due to an error in handling a client crafted certificate during the authentication phase. An attacker could exploit this vulnerability by trying to authenticate to the affected system using a crafted certificate. An exploit could allow the attacker to bypass the certificate authentication. Depending on the Cisco ASA configuration, this may allow the attacker to authenticate and access the network via Clientless or Anyconnect SSL VPN or to get administrative management access via Cisco Adaptive Security Device Management (ASDM).
Cisco has confirmed the vulnerability in a security advisory and released software updates.
Cisco Adaptive Security Appliance Software versions prior to 9.0(2.6)1 and 9.1(2) are vulnerable.
Only devices configured to allow client digital certification authentication are vulnerable to exploitation. In addition, only attackers who can establish a direct connection to a vulnerable device could conduct an exploit. These requirements greatly reduce the chance for exploitation.
An unauthenticated, remote attacker could exploit this vulnerability to gain unauthorized access to a targeted device.
This vulnerability is due to improper validation of client digital certificates.
An unauthenticated, remote attacker could exploit this vulnerability by connecting to a vulnerable device using a crafted digital certificate. The improper processing of the certificate could allow the attacker to bypass authentication requirements and gained unauthorized access to the targeted device.
Administrators are advised to apply the appropriate updates.
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.
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 email at firstname.lastname@example.org.
The security vulnerability applies to the following combinations of products.
Cisco Adaptive Security Appliance (ASA) Software
9.0 .1, .2 | 9.1 .1, .1.4
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