Apache Sling Framework 2.3.6 Information Disclosure

`Document Title:  
===============  
Apache Sling Framework v2.3.6 (Adobe AEM) [CVE-2016-0956] - Information Disclosure Vulnerability  
  
  
References (Source):  
====================  
http://www.vulnerability-lab.com/get_content.php?id=1536  
  
Adobe Bulletin: https://helpx.adobe.com/security/products/experience-manager/apsb16-05.html  
  
http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2016-0956  
  
Vulnerability Magazine: http://magazine.vulnerability-db.com/?q=articles/2016/02/10/apache-sling-fw-v236-remote-slingpostservlet-exception-vulnerability  
  
  
CVE-ID:  
=======  
CVE-2016-0956  
  
  
Release Date:  
=============  
2016-02-10  
  
  
Vulnerability Laboratory ID (VL-ID):  
====================================  
1536  
  
  
Common Vulnerability Scoring System:  
====================================  
6.4  
  
  
Product & Service Introduction:  
===============================  
Apache Sling is a web framework that uses a Java Content Repository, such as Apache Jackrabbit, to store and manage content. Sling applications use either scripts   
or Java servlets, selected based on simple name conventions, to process HTTP requests in a RESTful way. The embedded Apache Felix OSGi framework and console provide   
a dynamic runtime environment, where code and content bundles can be loaded, unloaded and reconfigured at runtime. As the first web framework dedicated to JSR-170   
Java Content Repositories, Sling makes it very simple to implement simple applications, while providing an enterprise-level framework for more complex applications.  
  
(Copy of the Vendor Homepage: http://sling.apache.org/)  
  
  
Adobe Experience Manager (AEM) provides a complete suite of applications for the Web Experience Management (WEM) of organizations.  
  
(Copy of the Vendor Homepage: https://docs.adobe.com/docs/en/aem/6-1.html )  
  
  
Abstract Advisory Information:  
==============================  
The Vulnerability Laboratory Core Research Team discovered a remote vulnerability in the official Apache Sling Framwork v2.3.6 software.  
  
  
Vulnerability Disclosure Timeline:  
==================================  
2016-02-10: Public Disclosure (Vulnerability Laboratory)  
  
  
Discovery Status:  
=================  
Published  
  
  
Affected Product(s):  
====================  
Apache Software Foundation  
Product: Apache Sling - Framework (Adobe AEM) 2.3.6  
  
  
Exploitation Technique:  
=======================  
Remote  
  
  
Severity Level:  
===============  
High  
  
  
Technical Details & Description:  
================================  
It seems that on some instances of AEM, due to lack of proper security controls and or misconfiguration, it is possible for remote unauthenticated   
users to enumerate local system files/folders that arent accessible publicly to unauthenticated users.  
  
This can be achieved by sending a `delete` requests to the SlingPostServlet which in return, responds back with a 500 exception page and the   
following exception message: (org.apache.sling.api.resource.PersistenceException - Unable to commit changes to session)  
  
No actual files are deleted with this request however, the HTML response contains a `ChangeLog` field which is where all enumerated folder/file   
names are displayed (if existing). For instance, following POC command can be used to reproduce the said behavior.  
  
curl -F``:operation=delete`` -F``:applyTo=/foldername/*`` http://website.com/path/file.html  
  
To reproduce this in real world, I found an adobe website which is currently affected with this behavior. You can use the following CURL command   
to reproduce the POC:  
  
curl -F``:operation=delete`` -F``:applyTo=/etc/*`` https://www.adobedemo.com/content/adobedemolab/welcome-page.html  
  
Note: This curl command should enumerate all files/folders which currently exist in /etc folder  
  
This vulnerability currently affects major websites i.e. almost every instance of Adobe AEM published on the internet. Some references are included below for reference.  
  
Affected Framework(s):  
Apache Sling  
  
Affected Product(s)  
Adobe AEM (All Versions)  
  
  
Proof of Concept (PoC):  
=======================  
The security vulnerability can be exploited by remote attackers without privilege system user account or user interaction.  
For security demonstration or to reproduce the vulnerability follow the provided information and steps below to continue.  
  
PoC:  
1. curl -F":operation=delete" -F":applyTo=/foldername/*" http://website.com/path/file.html  
2. curl -F":operation=delete" -F":applyTo=/etc/*" https://www.adobedemo.com/content/adobedemolab/welcome-page.html  
  
  
Solution - Fix & Patch:  
=======================  
The vulnerability is fixed in version Servlets POST 2.3.8. Please update by by automatic request or implement the manual fix.  
  
Adobe: Hot fix 6445 resolves an information disclosure vulnerability affecting Apache Sling Servlets Post 2.3.6 (CVE-2016-0956).  
  
  
Security Risk:  
==============  
The security risk of the exception software vulnerability in the apache sling framework is estimated as high. (CVSS 6.4)  
  
  
Credits & Authors:  
==================  
Vulnerability Laboratory [Research Team] - Ateeq Khan ([email protected]) [www.vulnerability-lab.com] (https://twitter.com/cybercrimenews)  
  
  
Disclaimer & Information:  
=========================  
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