Date: Tue, 2 Oct 2012 17:52:12 -0500 From: Raphael Geissert <geissert@...ian.org> To: Kurt Seifried <kseifried@...hat.com> Cc: oss-security@...ts.openwall.com Subject: Re: CVE request - mcrypt buffer overflow flaw On Tuesday 02 October 2012 14:20:20 Kurt Seifried wrote: > On 10/02/2012 12:42 PM, Raphael Geissert wrote: > > Kurt, > > > > I think at least one more CVE id needs to be assigned: > > > > On Saturday 15 September 2012 19:22:06 Raphael Geissert wrote: > >> On Tuesday 11 September 2012 10:19:38 Eygene Ryabinkin wrote: > >> > >> Another week, another couple of patches. One makes it use strncpy > >> and forces a NUL on the last byte of local_algorithm, local_mode, > >> and local_keymode. Their values are checked later on, so it seems > >> safe to pass unvalidated data. The size of the buffers is > >> hard-coded to avoid making many changes to the code. > > > > I think this needs a separate id, since fixes were released by > > Fedora and Debian referencing CVE-2012-4409 but only for the > > original report. > > > > Eygene's followup issues have been fixed in Debian without > > referencing a CVE id. > > Can you post a link to source fixes/commits? Thanks. This is all there is: http://www.openwall.com/lists/oss-security/2012/09/16/1 The Debian changelog is probably not of much use. > >> Once those issues were fixed I noticed that salt_size is not > >> initialized if the salt flag is not set. The result is an > >> inconditional call to malloc, with an uninitialized int as > >> argument. This can lead to a non-attacker-controlled memory > >> consumption DoS in most cases. It makes me think nobody actually > >> ever used it without a salt. > > > > I've no strong opinion on whether this deserves an id. > > > > Cheers, > > Hrmm there's a thought, has this DoS been confirmed? As we've probably > seen over the last year more than a few sites fail to salt their > stored passwords =(. I don't see how that is relevant, this is the mcrypt(1) tool in concern. libmcrypt and libmhash are not affected. The attached file is a PoC built with a slightly modified mcrypt. It appears that there is no way to disable the salt bit in the unmodified mcrypt while still producing a file that can later be opened. (for those looking at the code, the salt bit is only disabled when using --bare) Cheers, -- Raphael Geissert - Debian Developer www.debian.org - get.debian.net Download attachment "foo.nc" of type "application/x-netcdf" (76 bytes)
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