Re: CVE Request: pwgen

[Kurt Seifried <kseifried () redhat com>]

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On 05/24/2013 03:43 PM, Seth Arnold wrote:
> Hello Kurt, Steve, all,
>
> Do these issues deserve CVE numbers?
>
> A user reported to launchpad [1] that pwgen will use /dev/urandom
> or /dev/random if it can, but will silently fall back to using
> drand48() or random() if the device files fail to open. The report
> also mentions that when the device files are available, the output
> is biased by too-simple use of the modulo operator to scale the
> output to 0 <= n < max. There are further complaints about the poor
> use of available entropy when seeding the weaker algorithms.
>
> A potentially related complaint is in Debian's BTS [2]: in this
> bug report, the user wanted a way to force use of /dev/random even
> if /dev/urandom is available.
>
> I've pasted the relevant source to pastebin.ubuntu.com [3].
>
> Are any of these worthy of a CVE number?
>
> - silent fall-back to weak algorithms - biased output due to poor
> use of modulo operations - poor seeding of weak algorithms

Is any of this behaviour documented, or is it only "documented" in the
source code (I'm guessing source code only)? Also I'm trying to think
of situations where /dev/random and urandom are not available, AND the
system is otherwise working ok and nothing comes to mind. The fall
back is definitely sub-optimal, but can it be triggered in any
meaningful way.

> Thank you
>
> 1: https://bugs.launchpad.net/ubuntu/+source/pwgen/+bug/1183213 2:
> http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=672241 3:
> http://pastebin.ubuntu.com/5698361/


- -- 
Kurt Seifried Red Hat Security Response Team (SRT)
PGP: 0x5E267993 A90B F995 7350 148F 66BF 7554 160D 4553 5E26 7993
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