Cisco IOS XR Software contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service condition. Updates are available.
A vulnerability in Point-to-Point Tunneling Protocol-Application Level Gateway (PPTP-ALG) of the Cisco CRS Carrier Grade Services Engine (CGSE) and Cisco ASR 9000 Series Integrated Service Module (ISM) could allow an unauthenticated, remote attacker to cause the service interface module to reset.
The vulnerability is due to processing of packet sequences in the PPTP-ALG. An attacker could exploit this vulnerability by sending specific streams of traffic through the device. An exploit could allow the attacker to cause the service module to reset.
Cisco has confirmed the vulnerability in a security notice and released software updates.
At the time this alert was first published, Cisco IOS XR Software Releases 4.3.1 and prior were vulnerable. Later releases of Cisco IOS XR Software may also be vulnerable.
To exploit this vulnerability, the attacker must send a crafted stream of traffic through the targeted system. To achieve this objective, the attacker may need to access trusted, internal network resources. This access requirement reduces the likelihood 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.
Cisco has released a security notice at the following link: CVE-2013-5498
Customers are advised to consult Cisco bug ID CSCue91963 for the most complete list of affected product versions.
An unauthenticated, remote attacker could exploit this vulnerability to cause the service interface module on an affected device to reset, resulting in a denial of service (DoS) condition.
The vulnerability is due to the way the PPTP-ALG is used by the affected software processes packet sequences.
An unauthenticated, remote attacker could exploit this vulnerability by sending specific streams of traffic through the targeted device. If successful, the attacker could cause the service module on the device to reload, resulting in a DoS condition.
Administrators are advised to apply the appropriate updates.
Administrators can help protect affected systems from external attacks by using a solid firewall strategy.
Administrators are advised to allow only trusted users to have network access.
Administrators are advised to monitor affected systems.
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 firstname.lastname@example.org for assistance.
The security vulnerability applies to the following combinations of products.
Cisco IOS XR Software
4.3 .0, .1
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.