North American Network Operators Group
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Re: Cisco IOS Exploit Cover Up

  • From: Petri Helenius
  • Date: Fri Jul 29 16:36:25 2005 
Buhrmaster, Gary wrote:
The *best* exploit is the one alluded to in the presentation.
Overwrite the nvram/firmware to prevent booting (or, perhaps,
adjust the voltages to damaging levels and do a "smoke test").
If you could do it to all GSR linecards, think of the RMA
costs to Cisco (not to mention the fact that Cisco could not
possible replace all the cards in all the GSRs across the
internet in an anywhere reasonable timeframe). *THAT* is
what I suspect worries Cisco. But of course I am just
conjecturing...


One of the more effective (software) ways is to mess up the cookies on the cards which tell IOS what kinds of cards they are and then reload the box.

Fortunately destructive worms don't usually get too wide distribution because they don't survive long.

Pete

Gary

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Janet Sullivan
Sent: Friday, July 29, 2005 12:44 PM
To: [email protected]; [email protected]
Subject: Re: Cisco IOS Exploit Cover Up


Scott Morris wrote:

And quite honestly, we can probably be pretty safe in
assuming they will not

be running IPv6 (current exploit) or SNMP (older exploits)
or BGP (other

exploits) or SSH (even other exploits) on that box. :)
(the 1601 or the

2500's)

If a worm writer wanted to cause chaos, they wouldn't target 2500s, but 7200s, 7600s, GSRs, etc.

The way I see it, all that's needed is two major exploits, one known by Cisco, one not.

Exploit #1 will be made public. Cisco will released fixed code. Good service providers will upgrade.

The upgraded code version will be the one targeted by the second, unknown, exploit.

A two-part worm can infect Windows boxen via any common method, and then use them to try the exploit against routers. A windows box can find routers to attack easily enough by doing traceroutes to various sites. Then, the windows boxen can try a limited set of exploit variants on each router. Not all routers will be affected, but some will.

As for what the worm could do - well, it could report home to the worm creators that "Hey, you 0wn X number of routers", or it could do something fun like erasing configs and locking out console ports. ;-)

Honestly, I've been expecting something like that to happen for years now. <shrug>