full-disclosure - Re: "debug k" freezing Cisco routers?

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Date: Wed, 1 Aug 2007 18:51:14 +0200
From: Felix 'FX' Lindner <fx@...re-labs.com>
To: "Shawn Merdinger" <shawnmer@...il.com>
Cc: full-disclosure@...ts.grok.org.uk
Subject: Re: "debug k" freezing Cisco routers?

Hi Shawn,

On Wed, 1 Aug 2007 10:14:47 -0600 "Shawn Merdinger"
<shawnmer@...il.com> wrote:
> At level 15 permissions, when I enter "debug k" on the CLI the router
> freezes immediately, requiring a manual reboot.
> 
> While not a vulnerability per se, perhaps something to keep in mind
> from the fat-finger risk?

the full command is "debug kernel", and it halts the IOS kernel since
it will be in suspended state waiting for the serial line GDB debugger
to be attached and tell him to continue. Hence the freeze. 

BinNavi with GDB agent can use the serial line protocol to single-step
the IOS kernel. You can also just patch any gdb source you have around.

cheers
FX

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