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Date: Wed, 7 Mar 2018 11:09:50 +0100
From: Tomas Hoger <thoger@...hat.com>
To: Kurt Seifried <kseifried@...hat.com>
Cc: oss-security@...ts.openwall.com
Subject: Re: memcached UDP amplification attacks

On Fri, 2 Mar 2018 21:42:30 -0700 Kurt Seifried wrote:

> I have assigned CVE-2018-1000115 to this issue:
> 
> Memcached version 1.5.5 contains an Insufficient Control of Network
> Message Volume (Network Amplification, CWE-406) vulnerability in the
> UDP support of the memcached server that can result in denial of
> service via network flood (traffic amplification of 1:50,000 has been
> reported by reliable sources). This attack appear to be exploitable
> via network connectivity to port 11211 UDP. This vulnerability
> appears to have been fixed in 1.5.6 due to the disabling of the UDP
> protocol by default.

Minor nitpick, the description mentions 1:50,000 ratio, apparently
based on the information in the following reference:

> https://blogs.akamai.com/2018/03/memcached-fueled-13-tbps-attacks.html

where it's mentioned as:

"""
Worse, memcached can have an amplification factor of over 50,000,
meaning a 203 byte request results in a 100 megabyte response.
"""

However, 200 * 50k = 10m, not 100m.  Wonder if I'm doing my math wrong.

-- 
Tomas Hoger / Red Hat Product Security

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