Cisco Adaptive Security Appliance Software contains a vulnerability that could allow an authenticated, remote attacker to cause a denial of service condition on a targeted system. Updates are available.
Description
Cisco Adaptive Security Appliance (ASA) Software contains a vulnerability that could allow an authenticated, remote attacker to cause a denial of service (DoS) condition on a targeted system.
The vulnerability is due to the incorrect management of remote SSH sessions when two or more sessions are active to the ASA console. An authenticated, remote attacker could exploit this vulnerability by logging multiple SSH sessions to the targeted device. If successful, the attacker could cause the device to crash, resulting in a DoS condition.
Proof-of-concept code that exploits the vulnerability is publicly available.
Cisco has confirmed the vulnerability in a security notice and released software updates.
Warning Indicators
Cisco ASA Software versions 8.4(1) and prior are vulnerable.
IntelliShield Analysis
To exploit this vulnerability, an attacker must be able to authenticate to a targeted device to activate multiple SSH sessions, likely requiring the attacker to access trusted, internal networks. This access requirement limits the likelihood of a successful exploit.
Vendor Announcements
Cisco has released a security notice for Cisco bug ID CSCtc59462 at the following link: CVE-2012-5717
Impact
An authenticated, remote attacker could exploit this vulnerability to cause the targeted device to crash, resulting in a DoS condition.
Technical Information
The vulnerability is due to the incorrect management of remote SSH sessions when two or more sessions are active to the ASA console.
An authenticated, remote attacker could exploit this vulnerability by logging multiple SSH sessions to the targeted device, which could cause one of the sessions to time out. If successful, an attacker could cause the device to crash, resulting in a DoS condition.
Safeguards
Administrators are advised to apply the appropriate updates.
Administrators are advised to allow only trusted users to have network access.
Administrators are advised to monitor affected systems.
Patches/Software
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 tac@cisco.com.
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