Vulnerability Alert

Cisco IOS Software contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on a targeted system.

The vulnerability is due to the improper processing of crafted IP packets by the affected software when it is configured with the zone-based firewall feature.  An unauthenticated, remote attacker could exploit this vulnerability by sending specially crafted IP packets to a vulnerable device.  If successful, the attacker could cause the device to reload, resulting in a DoS condition.

Cisco has confirmed the vulnerability in a security advisory and released updated software.

Cisco has published a list of affected Cisco IOS Software releases in the security advisory.  The Vendor Announcements section of this alert contains a link to the advisory.

A successful exploit could allow an attacker to cause the vulnerable device to reload or stop responding, potentially preventing authorized users from accessing network resources served by the targeted device.

It is likely that the vulnerable device is behind a firewall that is between a public and private network. As a result, an attacker would need to have access to an internal network to send crafted IP packets to a vulnerable device.  This requirement could limit the possibility for an attack.

This alert contains CVSS scoring supplied by Cisco, the primary vendor of the affected product.  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 advisory for Cisco bug ID  CSCto89536 at the following link: cisco-sa-20120328-zbfw