A vulnerability in the VPN authentication code that handles parsing of the username from the certificate on the Cisco ASA firewall could allow an unauthenticated, remote attacker to cause a reload of the affected device. The vulnerability is due to parallel processing of a large number of Internet Key Exchange (IKE) requests for which username-from-cert is configured. An attacker could exploit this vulnerability by sending a large number of IKE requests when the affected device is configured with the username-from-cert command. An exploit could allow the attacker to cause a reload of the affected device, leading to a denial of service (DoS) condition. Cisco has confirmed the vulnerability in a security notice and released software updates. To exploit this vulnerability, an attacker must send a large number of IKE requests to a targeted device, which may reside on trusted, internal networks that the attacker would likely need to access. This access requirement decreases the likelihood of a successful exploit. In addition, the targeted device must be configured with the username-from-cert command. Cisco indicates through the CVSS score that functional exploit code exists; however, the code is not known to be publicly available.
The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.
To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.
| Version | Description | Section | Status | Date |
| 1.0 | Initial Release | NA | Final | 2013-Oct-22 |
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