oss-sec mailing list archives

Re: CVE assignments for "weak" crypto (was CVE Request: MD5 used for Download verification)


From: "Mike O'Connor" <mjo () dojo mi org>
Date: Wed, 13 Mar 2013 08:45:17 -0400

steve:The fundamental problem is in the MD5 algorithm itself; any
steve:implementation of MD5 will suffer from the same problems.  We have
steve:multiple CVE identifiers for the various weaknesses of MD5.  Any
steve:product that uses MD5 is therefore subject to these weaknesses.

Multiple?  I did a quick search of MD5 from thE CVE database:

http://cve.mitre.org/cgi-bin/cvekey.cgi?keyword=md5

and found only one that *didn't* look tied to a particular implementation.
Having said that...

tim:I think if an application relies on a cryptographic primitive for a
tim:property that it does not provide, or that it is KNOWN to be broken
tim:for (such as MD5 or SHA1 with collision resistance), then there should
tim:be a CVE assigned.  The cat's out of the bag on these things; there'st
tim:no excuse to use MD5 for this purpose.  The world knows these hashes

...the one CVE I found involving one of the "various weaknesses of
MD5" DID involve MD5 collision resistance:

http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2004-2761

However, the associated text might be misleading -- caps are mine:

         The MD5 Message-Digest Algorithm is not collision resistant, which
         makes it easier for CONTEXT-DEPENDANT attackers to conduct spoofing
         attacks, AS DEMONSTRATED BY ATTACKS ON THE USE OF MD5 IN THE
         SIGNATURE ALGORITHM OF AN X.509 CERTIFICATE.

While a careful reading of the text may lead one to conclude "X.509 is
just one example of MD5 b0rked-ness", someone who implements MD5 in a
non-X.509 cert context might easily gloss over this one.

Might it make sense to highlight some of these "fundamental" CVEs that
a diverse range of apps might be prone to?  Just thinking out loud here...

-Mike

-- 
 Michael J. O'Connor                                          mjo () dojo mi org
 =--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--=
"Make it so they have to reboot after every typo."     -the Pointy-Haired One

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