Security firm Symantec believes the widespread use of Cisco devices will be an irresistible target to malicious hackers.

Networking giant Cisco has announced the presence of a flaw in the Firewall Authentication Proxy for FTP/Telnet sessions. The proxy, part of Cisco’s IOS software that forms the heart of its devices, could fall victim to an exploitable buffer overflow condition.

“Given the recent attention to exploitation of vulnerabilities in Cisco’s IOS it is possible that this issue will see attempts at exploit development in the near term,” Symantec said in its advisory. Systems that only use the Authentication Proxy for http/https session are not vulnerable, according to Cisco, and the company has workarounds and fixes posted on its web site.

Cisco’s IOS was the focus of a controversial presentation at this year’s Black Hat conference in Las Vegas. A security professional named Michael Lynn quit his job with ISS and defied Cisco by going forward with a discussion on the innate vulnerability of the company’s IOS.

He predicted that, while the hole he was discussing had been fixed, others posing a similar threat would be found. This newest flaw subjects the specifically vulnerable Cisco devices to being shutdown by a denial of service attack, or worse, execution of arbitrary code by a remote user.

Cisco administrators of devices running versions 12.2ZH and 12.2ZL, 12.3, 12.3T, 12.4 and 12.4T of IOS need to either disable the proxy or restrict access to it to trusted systems. More information can be found in the advisory, or service contract holders can work with their usual points of contact for assistance.

David Utter is a staff writer for Murdok covering technology and business. Email him here.