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Date: Fri, 27 Apr 2012 14:40:48 -0600
From: Vincent Danen <vdanen@...hat.com>
To: oss-security@...ts.openwall.com
Subject: weak use of crypto in python-elixir can lead to information
 disclosure (CVE and peer review request)

Could a CVE be assigned for the following issue?

It was reported that python-elixir, a library for ORM mapping on top of
SQLAlchemy with support for encrypting data stored in a database,
suffers from weak use of cryptography.  It uses Blowfish in CFB mode,
which has an additional parameter (IV), which is not specified and thus
defaults to zero.  CFB mode is only secure if the the IV is
unpredictable and different for every message.  Because of this, and
because the encryption key is shared for each database table (fields and
rows), the same plaintext prefix is always encrypted to an identical and
corresponding ciphertext prefix.  As a result, an attacker with access
to the database could figure out the plaintext values of encrypted text.


References:

https://bugzilla.redhat.com/show_bug.cgi?id=810013
http://groups.google.com/group/sqlelixir/browse_thread/thread/efc16227514cffa?pli=1
http://elixir.ematia.de/trac/ticket/119


So far there has been no response from upstream, and we have what I
think is a suitable proposal to fix the flaw and a possible migration
script to ease migrating from an insecure encrypted db to a secure one
(noted in the google groups message).

Not sure if anyone else is shipping python-elixir at all, but if you
are, input on the proposed fix and migration script (in the absence of
an upstream response) would be fantastic.

-- 
Vincent Danen / Red Hat Security Response Team 

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