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Parallels Remote Application Server (RAS) 15.5 Path Traversal

Posted in Advisories Written by Nicolas Markitanis (R3D)

Exploit Title: Parallels Remote Application Server (RAS) Path Traversal
Date: 22-02-2018
Exploit Author: Nicolas Markitanis
Reviewers: Simon Loizides and Marios Nicolaides
Vendor Homepage: Parallels
Affected: Parallels Remote Application Server (RAS) 15.5
Tested on: Parallels Remote Application Server (RAS) 15.5 Build 16140
CVE-ID: CVE-2017-9447
Category: Web Application


OVERVIEW
The web interface of the Parallels Remote Application Server is vulnerable to Path Traversal.

The vulnerability exists due to improper validation of the file path when requesting a resource under the RASHTML5Gateway directory.

A remote, unauthenticated attacker could exploit this weakness to read arbitrary files from the vulnerable system using path traversal sequences ("..\\\").

This was tested on Parallels RAS 15.5 (build 16140). Previous versions of may also be affected.


DETAILS
An attacker could exploit this vulnerability by using path traversal sequences ("..\\\") to access sensitive information as demonstrated below:

https://example.runesec.com/RASHTML5Gateway//..\\\..\\\..\\\..\\\..\\\windows\win.ini

Please note that the file accessed (win.ini) is for demonstration purposes only.


IMPACT

An attacker could exploit this vulnerability to gain unauthorized read access to sensitive files located outside of the web root directory. By doing so, an attacker might also be able to compromise valid sessions in order to gain unauthorized access to the RAS interface.


MITIGATION

Update to the newest version of Parallels RAS 15.5 - Parallels Remote Application Server v.15.5 Release Notes


REFERENCES


TIMELINE

5 June 2017 - Parallels informed about the issue
September 2017 - Parallels released a patch
22 February 2018 - Exploit publicly disclosed

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