Cisco Adaptive Security Appliance Software contains a vulnerability that could allow an unauthenticated, remote attacker to bypass security restrictions and access the SSL VPN Portal web page. Updates are available.
A vulnerability in the SSL VPN code could allow an unauthenticated, remote attacker to access
the SSL VPN portal web page.
vulnerability is due to improper handling of authentication cookies
when the Cisco ASA SSL VPN feature is enabled. An
attacker could exploit this vulnerability by manually modifying the HTTP
POST body with a forged cookie value or entering a crafted URL. An
exploit could allow the attacker to gain unauthenticated access to the SSL VPN Portal page. Depending on the SSL VPN configuration, the attacker may also start a VPN tunnel by using Cisco AnyConnect.
In all cases, the attacker may gain unauthorized access to internal network resources.
Cisco has confirmed the vulnerability in a security advisory and released software updates.
The following Cisco ASA Software versions are affected:
Cisco ASA Software versions prior to 8.2(5.47)
Cisco ASA Software versions prior to 8.3(2.40)
Cisco ASA Software versions prior to 8.4(7.3)
Cisco ASA Software versions prior to 8.6(1.13)
Cisco ASA Software versions prior to 9.0(3.8)
Cisco ASA Software versions prior to 9.1(3.2)
To exploit the vulnerability, the attacker may provide a link that directs a user to a malicious site and use misleading language or instructions to persuade the user to follow the provided link.
The SSL VPN feature must be enabled on a targeted device to exploit this vulnerability. Successful exploitation could allow the attacker to start a VPN tunnel via the AnyConnect client or by using SSL VPN cookies during the creation of an SSL VPN session. Both scenarios could allow unauthorized access to network resources that could be used to conduct further attacks.
An unauthenticated, remote attacker could exploit this vulnerability to gain unauthorized access to internal network resources. A successful exploit could be used to conduct further attacks.
The vulnerability is due to improper handling of authentication cookies by the affected software when the SSL VPN feature is enabled.
An attacker could exploit this vulnerability by submitting a crafted URL to the targeted device. An exploit could allow the attacker to gain unauthenticated access to the SSL VPN Portal page and, depending on the SSL VPN configuration, start a VPN tunnel via AnyConnect.
Administrators are advised to apply the appropriate updates.
Administrators are advised to allow only trusted users to have network access.
Administrators can help protect affected systems from external attacks by using a solid firewall strategy.
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 email@example.com.
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