[SECURITY ISSUE] CVE-2015-0276: Lack of CSRF attack protection enables gaining unauthorised access to users' accounts

[Kallithea Security Team]

Dear users,

We've discovered a security issue in Kallithea. We recommend you to
upgrade your instances to avoid possible attacks. The details of the
security notice follow below.

Synopsis
========

A vulnerability has been found in Kallithea, allowing attackers to gain
unauthorised access to account of a logged in user.

Description
===========

Pages presentings forms to the user and accepting user's input don't
provide synchronisation tokens to prevent cross-site request forgery.

It is possible to change an email address of a user by tricking them
into clicking a link that initiates the following HTTP request:

    POST /_admin/my_account HTTP/1.1
    Host: <DELETED>
    User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:35.0)
    Gecko/20100101 Firefox/35.0 Accept:
    text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
    Accept-Language: en-US,en;q=0.5 Accept-Encoding: gzip, deflate
    Referer: http://burp/show/1
    Cookie: kallithea=<DELETED>
    Connection: keep-alive
    Content-Type: application/x-www-form-urlencoded
    Content-Length: 146

    username=myAccount&extern_name=kallithea&extern_type=kallithea&firstname=myFirstname&lastname=myLastname&email=emailAddress%40example.com&save=Save

After this, the attacker can request a password reset, the link is then
sent to their new email address. Then the attacker changes the email
address back to the original, and doesn't log out, saving the cookie.

At this point, the attacker has full access to the user's account. The
user can't login (the password has changed), but might think that he
forgot their password, has an account lockout, or an expired account.
The user does a password reset, but the attacker still has the access.

Impact
======

The vulnerability allows attacker to steal account of an active user by
using social engineering techniques. In the case the user also has
administrator rights, it is possible for the attacker to gain full
administrator access to the Kallithea instance.

Resolution
==========

Kallithea project has fixed this issue by adding CSRF checks to the form
generation code. Before the fix, there none of the forms had CSRF
protection, with the fix, all POST forms are protected against CSRF.

There's no fix as a standalone patch, however; instead, it is
recommended to upgrade to the latest 0.2 release which includes lots of
other changes and improvements.

Affected versions
=================

The issue is currenly present in all Kallithea versions before 0.2.

References
==========

[1] CVE-2015-0276
    <http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-0276>

[2] Kallithea: Security Notice CVE-2015-0276
    <https://kallithea-scm.org/security/cve-2015-0276.html>

-- 
Cheers,
  Andrew Shadura
  on behalf of Kallithea Security Team
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