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Date: Mon, 3 Feb 2014 19:19:06 +0000 (UTC)
From: mancha <mancha1@...h.com>
To: oss-security@...ts.openwall.com
Subject: Re: OpenSSH J-PAKE vulnerability (no cause for panic! remain calm!)

Kurt Seifried <kseifried@...> writes:
> On 01/29/2014 06:50 AM, cve-assign@... wrote:
> > Use CVE-2014-1692. The CVE description will indicate that the
> > issue requires an unusual installation.
> > 
> >> As I understand it this can be enabled via code edit/gcc command
> >> line options, so not sure if this qualified for a CVE or not
> >> (vuln in code, yes, is code reachable? not under any default
> >> setup, and even on non-default you have to go pretty far off to
> >> enable it).
> > 
> > An impact on the default installation isn't necessary.
> > Vulnerabilities that occur only after the user modifies code aren't
> > eligible for a CVE. However, if there's some type of "installation
> > option" mentioned by the vendor, someone may have chosen that
> > option, and it may be worthwhile to track the issue with a CVE. The
> > nature of an "installation option" obviously varies widely across
> > both open-source and closed-source products.
> > 
> > In this case, there's:
> > 
> >> http://www.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/Makefile.inc
> >
> >>  Add support for an experimental zero-knowledge password
> >> authentication method using the J-PAKE protocol ...
> > 
> >> This is experimental, work-in-progress code and is presently 
> >> compiled-time disabled (turn on -DJPAKE in Makefile.inc).
> > 
> >>
http://www.openbsd.org/cgi-bin/cvsweb/~checkout~/src/usr.bin/ssh/Makefile.inc?rev=1.41;content-type=text%2Fplain
> >
> >>  #CFLAGS+=	-DJPAKE
> > 
> > This is close to the edge of what "installation option" means, but
> > our feeling is that the vendor wouldn't have provided that #CFLAGS
> > line at all unless it were expected that an end user might want to
> > make the one-character change.
> 
> Just to close this email thread, Mitre assigned one:
> 
> http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-1692
> 

This CVE assignment puzzles me. Relevant code was: 1) never enabled,
2) never advertised in release notes, and 3) never had a
configuration option. To enable it, a user would have to pro-actively
edit code (more than merely a configure flag). Note: I *did* read
MITRE's justification on this last point.

Also, an attacker would need to make EVP_Digest* fail. Is there
a known way to achieve this?

Finally, the NVD entry
(https://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2014-1692)
doesn't make sense. J-PAKE experimental code wasn't in the code-base
until OpenSSH 5.2 (iirc) yet versions back to 1.2 are listed as
vulnerable. Also, a CVSS score of 7.5 (High)? I know this is 
orthogonal to the actual CVE assignment. Still...weird.

I don't have a horse in this race but the entire situation strikes
me incongruent.

--mancha





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