Cisco Firewall Services Module Software contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service condition. Updates are available.
Description
Cisco Firewall Services Module (FWSM) for the Cisco Catalyst 6500 Series switches and Cisco 7600 Series routers that use Cisco Firewall Services Module Software contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition.
The vulnerability is due to the exhaustion of resources on a targeted device when handling multiple requests. An unauthenticated, remote attacker could exploit this vulnerability to by sending a large number of requests to the device, causing the device to reload and leading to a DoS condition.
Cisco has confirmed this vulnerability in a security advisory and has released updated software.
Warning Indicators
Cisco Firewall Services Module Software releases prior to the following are vulnerable:
3.1(21)
3.2(22)
4.0(16)
4.1(7)
IntelliShield Analysis
It is likely that an attacker would need to have access to an internal, private network to send a high number of network access authentication requests. This requirement could limit the possibility of a potential attack.
Cisco indicates through the CVSS score that functional exploit code exists; however, the code is not known to be publicly available.
An unauthenticated, remote attacker could exploit this vulnerability to cause a targeted device to reload, resulting in a DoS condition. Repeated attacks could result in a sustained DoS condition.
Technical Information
The vulnerability is due to the exhaustion of resources when the device tries to process a high number of network access authentication requests.
An unauthenticated, remote attacker could exploit this vulnerability by sending a high number of network access authentication requests to a device that is running a version of the affected software. If successful, the attacker could cause a DoS condition by having the device reload. If the attacks are repeated, a sustained DoS condition may occur.
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 implement an intrusion prevention system (IPS) or intrusion detection system (IDS) to help detect and prevent attacks that attempt to exploit this vulnerability.
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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LEGAL DISCLAIMER The urgency and severity ratings of this alert are not tailored to individual users; users may value alerts differently based upon their network configurations and circumstances. THE ALERT, AND INFORMATION CONTAINED THEREIN, ARE PROVIDED ON AN "AS IS" BASIS AND DO NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. YOUR USE OF THE ALERT, AND INFORMATION CONTAINED THEREIN, OR MATERIALS LINKED FROM THE ALERT, IS AT YOUR OWN RISK. INFORMATION IN THIS ALERT AND ANY RELATED COMMUNICATIONS IS BASED ON OUR KNOWLEDGE AT THE TIME OF PUBLICATION AND IS SUBJECT TO CHANGE WITHOUT NOTICE. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE ALERTS AT ANY TIME.
