Standard random number generators (using shuffle ) should not be used to generate randomness

[Zhang Yun]

In cinder code : /cinder/utils.py . Below two lines of code used shuffle to generate a random number, Standard random number generators should not be used to generate randomness used for security reasons. Could we use a crytographic randomness generator to provide sufficient entropy to instead of it?

 # If length < len(symbolgroups), the leading characters will only
 # be from the first length groups. Try our best to not be predictable
 # by shuffling and then truncating.
 r.shuffle(password) ----------------> This line of code has described issue.
 password = password[:length]
 length -= len(password)

# finally shuffle to ensure first x characters aren't from a
# predictable group
r.shuffle(password) ----------------> This line of code has described issue.

return ''.join(password)

[Thierry Carrez (ttx)]

Cinder devs: could you comment on how much those "random" numbers are used in a security context ? We need to determine is this would be a welcome strengthening (no advisory published) or an exploitable vulnerability (advisory published).

[John Griffith (john-griffith)]

This is used by some drivers to generate a CHAP secret, the base driver as well as IBM/Storwize and HP/Lefthand. I'm not sure I agree that his is a security concern at all.

While in general rand and shuffle should not be used for setting secure passwords, the algorithm here does a number of things in addition to rand and shuffle by then also filling in random symbols. Regardless, given that this is for a CHAP setting only I think that this can be improved without a security advisory or notification.

[Jay Bryant (jsbryant)]

I second John's sentiment. I think it would be good to strengthen security here but an advisory is not necessary.

[Jeremy Stanley (fungi)]

I've removed the advisory task, switched the bug from public security (indicating some sort of actual vulnerability) to public, and added the "security" tag to indicate it's a potential strengthening opportunity.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/105779

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/105779
Committed: https://git.openstack.org/cgit/openstack/cinder/commit/?id=063e515e780c241ddac755b0b9a2414316d983f5
Submitter: Jenkins
Branch: master

commit 063e515e780c241ddac755b0b9a2414316d983f5
Author: Ivan Kolodyazhny <email address hidden>
Date: Wed Jul 9 19:08:18 2014 +0300

    Use PyCrypto to generate randomness passwords

    Standard random generator is not secure enouph. Use PyCrypto instead.
    Updated requirements.txt with pycrypto>=2.6 according to
    global-requirements

    Change-Id: I38fd47a30893a946de30fad95c57759781312be6
    Closes: bug #1319639