Cisco's TCP stack is vulnerable to attack

CISCO SYSTEMS has announced that several of its products have vulnerabilities that could be exploited with denial of service attacks.

Today the company said that the flaws could be used to manipulate TCP connections, forcing them into an indefinitely long-lived state. In order to take advantage of the vulnerabilities a hacker need only complete a three-way TCP handshake with a vulnerable system, Cisco said.

Some Cisco hardware apparently is more vulnerable to the problems than others. For example, Nexus 5000 devices harbour a TCP denial of service vulnerability that could lead to system crashes.

Affected systems include Linksys and Scientific Atlanta Products, Cisco's ASA and PIX security appliances and a range of its IOS and OS software releases. Software updates have already been released by the firm to deal with these known issues. Cisco added that workarounds, including a simple reboot, are also options. Concerned users are advised to read the firm's security advisory.

The TCP state manipulation vulnerabilities were reported to Cisco by Robert E. Lee and Jack Louis of Outpost24. So far no exploits have been detected in the wild, according to the firm. µ