oss-sec mailing list archives
Re: memcached UDP amplification attacks
From: Patrick Forsberg <fors () cert sunet se>
Date: Wed, 7 Mar 2018 23:33:37 +0100
On 2018-03-07 22:57, Seaman, Chad wrote:
Tomas, You’re not wrong, that was a typo in the blog. Regards, Chad
On the other hand I think the blog is wrong. (Just reading the protocol specs) The default maximum size of an item is 1M, but you can easily request more than one item using the gets command. gets <key>*\r\n where <key>* is one or several keys separated by whitespace. A key is a text string that must not include control characters or whitespace. The maximum length of a key is 250 characters but I don't think there's a minimum size so one byte keys should be fine. /Patrick
On 3/7/18, 5:10 AM, "Tomas Hoger" <thoger () redhat com> wrote: 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
Current thread:
- memcached UDP amplification attacks Hanno Böck (Mar 02)
- Re: memcached UDP amplification attacks Kurt Seifried (Mar 02)
- Re: memcached UDP amplification attacks Kurt Seifried (Mar 02)
- Re: memcached UDP amplification attacks Tomas Hoger (Mar 07)
- Re: memcached UDP amplification attacks Kurt Seifried (Mar 07)
- Re: memcached UDP amplification attacks Seaman, Chad (Mar 07)
- Re: memcached UDP amplification attacks Patrick Forsberg (Mar 08)
- Re: memcached UDP amplification attacks Seaman, Chad (Mar 08)
- Re: memcached UDP amplification attacks Kurt Seifried (Mar 02)
- Re: memcached UDP amplification attacks Kurt Seifried (Mar 02)