Crackers exploit Cisco LAN switch flaw

[InfoSec News <isn () c4i org>]

http://www.theregister.co.uk/content/55/23900.html

By John Leyden
Posted: 31/01/2002 at 13:40 GMT

Cisco has warned users of a potential denial of service risk involving
its popular Catalyst LAN switches.

A buffer overflow vulnerability in Telnet option handling can be used
to crash the process and force a Catalyst switch to reload. This
operation could be repeated by an attacker to produce a denial of
service attack.

Cisco Catalyst switches, series 4000, 5000 and 6000 and also 2948G and
2900 models, running CatOS are affected by the flaw, which Cisco warns
has already been exploited. Other Cisco LAN switches and routers are
immune.

The networking giant is offering free software upgrades to affected by
the flaw and published a schedule for the availability of fixed
releases, which shows fixes will be available by February 4.

Cisco is advising users to upgrade software on affected switches as
soon as is becomes available. In the meantime, workarounds to prevent
attacks, such as using SSH instead of Telnet, or applying access
control lists (ACLs) on routers and firewalls in front of vulnerable
boxes, can be applied.

The Catalysts switch vulnerability is related to a flaw involving
systems running versions of telnetd derived from BSD source, which was
discovered in July last year. At the time this problem was thought to
relate mainly to Unix systems, but it is now clear it also affects LAN
switches.



-
ISN is currently hosted by Attrition.org

To unsubscribe email majordomo () attrition org with 'unsubscribe isn' in the BODY
of the mail.