RE: ICMP Parameter Problem packets to random addresses

["Fernando Cardoso" <fernando.cardoso () whatevernet com>]

> Greetings All
>               Periodically, over the last few months, I have been
> seeing bursts of ICMP Parameter Problem (type 12, code 0) like those
> below that were picked up by snort today:
>
> Jun 19 10:01:34 takahe snort[64968]: PING-ICMP Parameter Problem:
> 194.42.253.254 -> 130.216.186.122
[...]
> I have been assuming that this traffic is a fall out from a DoS
> lauched against 194.42.253.254 (or some host behind it if it is a
> router).  One thing that might cause this is ICMP packets that set
> random values to type and code fields in a flood attack.  I seem to
> remember that one of the common DoS Tools does just that.
>
> Any other thoughts?

I agree with your assumptions, but I don't recall any common DoS tool that
can cause that sort of behaviour. There's an obscure(?) DoS exploit for
Linux 2.2.x Kernel that works by flooding a box with ICMP random stuff.
Here's part of the relevant code:

            icmph.iph.daddr = addrs.sin_addr.s_addr;
            icmph.iph.frag_off = htons(0);
            icmph.icp.icmp_type = random() % 14;
            icmph.icp.icmp_code = random() % 10;
            icmph.icp.icmp_cksum = 0;
            icmph.icp.icmp_id = 2650;
            icmph.icp.icmp_seq = random() % 255;
            icmph.icp.icmp_cksum = in_cksum((int *)&icmph.icp, 1024);

If you are using -d option on snort you can check for what type of
pointer-error ICMP is giving.

Cheers

Fernando

--
Fernando Cardoso - Security Consultant       WhatEverNet Computing, S.A.
Phone : +351 21 7994200                      Praca de Alvalade, 6 - Piso 6
Fax   : +351 21 7994242                      1700-036 Lisboa - Portugal
email : fernando.cardoso () whatevernet com     http://www.whatevernet.com/



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