Multiple flaws in Cisco router software exposed

Cisco Systems has warned that multiple vulnerability with the operating system used by its 600 series routers leave its vulnerable to a barrage of attacks.

Last night, Cisco issued an alert which admitted that 600 series routers was subject to not one, not two, not three but four potentially serious flaws. It advised users to upgrade the software.

One flaw with Cisco CBOS Software, which runs on 600 series routers, means that passwords are stored in clear text in the memory of a router.

If that doesn't take the fancy of crackers they may be interested to learn that when multiple, large ECHO REPLY packets are routed through an affected Cisco 600 router it will stop passing any further traffic.

If denial of service attacks are not to the taste of the s'kiddie in question perhaps he might care to partake in a spot forgery. Another CBOS bug makes it possible to make a successful prediction of TCP Initial Sequence Numbers.

This makes it possible for crackers to modify or intercept traffic that either originates at or terminates at a 600 series device, but doesn't affect traffic flowing through a router in transit between two other points.

Not good - and there's more.

The last flaw means a Cisco 600 router may stop passing traffic or responding to a console when an ECHO REQUEST packet with the record route option is sent through it. It's just as well exploits that involve breaking router security are generally beyond the expertise of most s'kiddies.

The solution to all these problems is to upgrade from earlier software to either of the following CBOS releases: 2.3.9, 2.4.1 and 2.4.2. More information on the issue is available here.

In writing the story we were struck with an odd sense of deja vu. Indeed last December, Cisco was forced to admit a similar (though different) set of FOUR security flaws that affected 600 series routers.

In December we speculated as to why Cisco had not issued a separate notice for each vulnerability, since each was different. At the time we speculated that Cisco might bunch vulnerability notices together in order to encourage users to upgrade their software. Maybe just one potentially devastating flaw isn't good enough.

We still reckon these batch vulnerability notices are a technique used by Cisco to migrate users to newer versions of its software that tie them even closer to it. Such a move would make great business sense and we'd dearly love to quiz Cisco on this.

Unfortunately Cisco (which has a reputation as having the worst PR of any company in IT among UK journalists) hasn't spoken to us for months and so we're unlikely to be able to ask them anything. If anyone at Borg Central is listening: if we offered cash for interviews would it make any difference? ®

Related Link

Cisco's security notice

Related Stories

Cisco 600 routers offer cracker fun