full-disclosure - Re: SNMP Reflected Denial Of Service

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Date: Mon, 03 Sep 2012 09:20:39 +0300
From: Anestis Bechtsoudis <bechtsoudis.a@...il.com>
To: Full Disclosure <full.disclosure@...dex.ru>
Cc: "full-disclosure@...ts.grok.org.uk" <full-disclosure@...ts.grok.org.uk>
Subject: Re: SNMP Reflected Denial Of Service - PoC

Just tested on Windows 2003R2 & 2008R2 Server snmpd with same results
(no reflection). If you could name some devices/services that this
getBulk vector works will be extremely useful.



-A

On 9/3/12 1:03 AM, Full Disclosure wrote:
> Actually, if you test it against windows snmpd or a lot of Cable modems out there, the getbulk request causes a 1500 byte packet reply.
> You probably tested it against linux snmpd or cisco, which in that case , yes, it returns null. 
> 
> 31.08.2012, 09:31, "Anestis Bechtsoudis" <bechtsoudis.a@...il.com>:
>> On 8/30/12 8:13 PM, Full Disclosure wrote:
>>
>>>  Hi list,
>>>
>>>  I am releasing this code due to the fact that my dev server got hacked and people have been using it in the wild for bad things.
>>>
>>>  Network admins should patch their networks appropriately by rejecting snmp connections from unwanted IPs.
>>
>> The quoted code is actually nothing more than a regular threaded UDP
>> flood DoS tool, both SNMP spoofed requests and responses are equally 65
>> bytes (no reflection). Make a simple network capture for verification.
>>
>> The payload is a mis-used .1.3.6.1 getBulk SNMP request resulting in a
>> null value response.
>>
>> A sample perl script with the biggest reflection factor per transaction
>> achieved on Cisco devices is available here [1] (Amplification = 84
>> bytes request / 1480 bytes response).
>>
>> For more information about SNMP reflection DoS you may refer to this
>> link [2].
>>
>> The quoted code reminds me an old implementation on the same concept [3].
>>
>> [1] http://pastebin.com/M9cJs89h
>> [2] https://bechtsoudis.com/hacking/snmp-reflected-denial-of-service/
>> [3] http://packetstormsecurity.org/DoS/snmpdos.c
>>
>> -A
>>
>> --
>> #----------------------------------------------#
>> | Anestis Bechtsoudis                          |
>> |                                              |
>> | Network Operation Center,                    |
>> | Laboratory for Computing (LabCom),           |
>> | Dept. of Computer Engineering & Informatics, |
>> | University of Patras, Greece                 |
>> |----------------------------------------------|
>> | Public Key: http://bit.ly/Q2f5gW             |
>> | Website: https://bechtsoudis.com             |
>> #----------------------------------------------#

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