Vulnerability leaves Cisco small biz routers wide open to attack

Exploit code available, but no patch until end of the month

A number of Cisco networking products for small businesses contain critical vulnerabilities that could allow attackers to gain root access to the equipment, the networking giant has warned.

The affected products include the WAP4410N Wireless-N Access Point, the WRVS4400N Wireless-N Gigabit Security Router, and the RVS4000 4-port Gigabit Security Router, Cisco said in a security advisory issued late on Friday.

Note that these products are all branded Cisco and not Linksys. Cisco marketed consumer and small business networking equipment under the Linksys brand for ten years beginning in 2003, but sold the division to Belkin in January 2013.

According to Cisco's advisory, the vulnerabilities in all three products stem from an undocumented test interface that listens on TCP port 32764 on the affected devices.

Attackers can potentially exploit that interface to execute arbitrary commands on the underlying operating system, the advisory explains. By doing so, Cisco adds, they can potentially gain the administrator password to the device, which would then allow them to execute commands with elevated privileges.

The most obvious use for such an exploit would be to trigger a denial-of-service attack on a network by freezing up the router or resetting it to its factory default configuration.

Cisco has ranked the vulnerabilities at 10.0 on the Common Vulnerability Scoring System (CVSS) – the highest possible score, which indicates a critical flaw.

Worst of all, public exploit code for the vulnerabilities is already available, although Cisco says it has not seen any widespread attacks based on the exploit so far.

There are no known workarounds for the vulnerabilities and Cisco has not released any patches as yet, although it promises it will ship fixes for all three routers by the end of January 2014. Until then, El Reg advises users of the affected products to cross their fingers. ®

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