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Message-ID: <51CA76E6.1060002@redhat.com>
Date: Tue, 25 Jun 2013 23:06:46 -0600
From: Kurt Seifried <kseifried@...hat.com>
To: oss-security@...ts.openwall.com
CC: Michael Samuel <mik@...net.net>, security@....org
Subject: Re: KDE Paste Applet
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
On 06/25/2013 10:39 PM, Michael Samuel wrote:
> On 13 June 2013 10:02, Michael Samuel <mik@...net.net> wrote:
>
>> Ok, so the fix for this uses KRandom::random()...
>>
>> I suggest leaving the KDE Paste fix as-is and replacing KRandom
>> with something that just fills an integer from /dev/urandom -
>> then we can save a few CVE numbers for the rest of the year.
>>
>> qrand() should probably also do the same, especially since
>> cnonces for HTTP auth are using it - that means there's only 2^32
>> (at best) possible cnonces...
>>
>>>
>>>
> Fedora and Ubuntu have both pushed out this patch. Requesting a
> new CVE for "KRandom::random() isn't a secure PRNG", since the KDE
> guys are convinced that it is.
>
> Regards, Michael
So the thing is it can be completely random, just like a coin flip.
But the search space might be to small (e.g. a 1 bit key based on a
coin flip wouldn't be "secure"). I suspect 2^32 isn't enough any more
either, assuming a 480 core GPU, if you can run 250 cracking attempts
per second per core you can brute force a 2^32 search space in 10
hours or so. Needless to say GPUs are getting pretty cheap. So this
appears to be a textbook example of CWE-334 "Small Space of Random
Values".
Please use CVE-2013-2213 for KDE KRandom::random() CWE-334: Small
Space of Random Values.
- --
Kurt Seifried Red Hat Security Response Team (SRT)
PGP: 0x5E267993 A90B F995 7350 148F 66BF 7554 160D 4553 5E26 7993
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