RE: Re: Warning: Cisco RW community backdoor.

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-----Original Message----- From: owner-nznog(a)list.waikato.ac.nz [mailto:owner-nznog(a)list.waikato.ac.nz]On Behalf Of Joe Abley Sent: Monday, February 26, 2001 5:55 PM To: nznog(a)list.waikato.ac.nz Subject: Fw: Re: Warning: Cisco RW community backdoor.

More details below.

-----Original Message----- From: "James A. T. Rice" Date: Tue, 27 Feb 2001 01:46:37 +0000 (GMT) Subject: Re: Warning: Cisco RW community backdoor. To: , , ,

Just a couple of things to note,

I've been asked what the backdoor is, if its the community "ILMI" or if that was just an example, the answer is yes - "ILMI" is the backdoor which gives read-write access to parts of the SNMP base.

Its looks like parts of my earlier email are somewhat misleading, the ILMI community appears to only allow RW access to the system object and possibly some more objects. Its not a 'standard' open RW community. hence the damage caused by this backdoor is limited. There is still some write access however, so the fix mentioned below is still highly recommended.

And of course - it allows people to read what IOS/model cisco you have, which could be used to find exploitable bugs in that particular release. Oh I wonder what the chances of having a router stolen due to discovery of system.sysLocation is! :-)

Warm Regards James

-- James A. T. Rice | Email: jamesr(a)rd.bbc.co.uk Internet Operations Engineer | Phone: 01737 839 737 BBC Internet Services, Kingswood Warren, Tadworth, Surrey, UK.

On Tue, 27 Feb 2001, it was written:

...

If your router responds to `snmpwalk router.isp.net.uk ILMI`, you probabally will want to do the following to disable it: conf t snmp-server community ILMI RO 99 access-list 99 deny any log (pick another spare access-list if 99 isn't available)

If you dont, assuming your ios/hardware combination supports it, (most of the bigger routers do) anyone can do things like: `snmpset router.isp.net.uk ILMI system.sysName.0 s \ "ALL YOUR ROUTER ARE BELONG TO US."` Thats a harmless example. You can do almost anything with RW snmp.

Warm Regards James

-- James A. T. Rice | Email: jamesr(a)rd.bbc.co.uk Internet Operations Engineer | Phone: 01737 839 737 BBC Internet Services, Kingswood Warren, Tadworth, Surrey, UK.

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