Multiple flaws in Cisco router software exposed

[InfoSec News <isn () c4i org>]

http://www.theregister.co.uk/content/5/19148.html

By John Leyden
Posted: 23/05/2001 at 13:10 GMT

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.

Late 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 seperate
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?

[Cisco's security notice: 
http://www.cisco.com/warp/public/707/CBOS-multiple2-pub.html ]




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