[Full-disclosure] Security Advisory AA-004: Directory Traversal Vulnerability in Sitecom Home Storage Center

[Mattijs van Ommeren <mattijs@xxxxxxxxx>]

Security Advisory AA-004: Directory Traversal Vulnerability in Sitecom Home 
Storage Center

Severity Rating: High
Discovery Date: July 29, 2012
Vendor Notification: July 30, 2012
Disclosure Date: September 3, 2012

Vulnerability Type=
Directory Traversal

Impact=
- System Access
- Exposure of sensitive information

Severity=
Alcyon rates the severity of this vulnerability as high due to the following 
properties:
- Ease of exploitation;
- No authentication credentials required;
- No knowledge about individual victims required;
- No interaction with the victim required;
- Number of Internet connected devices found.

Products and firmware versions affected=
- Sitecom MD-253 firmware version up to and including 2.4.17
- Sitecom MD-254 firmware version up to and including 2.4.17
- Possibly other rebranded Mapower network storage products

Risk Assessment=
An attacker can read arbitrary files, including the files that stores the 
administrative password.
This means an attacer could:
- Steal sensitive data stored on the device;
- Leverage the device to drop and/or host malware;
- Abuse the device to send spam through the victim’s Internet connection;
- Use the device as a pivot point to access locally connected systems or launch 
attacks directed to other systems.

Vulnerability=
The CGI-script that is responsible for showing the device logs is affected by a 
directory traversal vulnerability that 

allows an attacker to view arbitrary files.

Proof of Concept Exploit=
Paste the following URL into a web browser’s address bar to obtain the 
administrator’s username and password:

  
http://<victimIP>/cgi-bin/info.cgi?syslog&../../etc/sysconfig/config/webmaster.conf

Risk Mitigation=
At the time of disclosure no updated firmware version was available.
We recommend that you limit access to the devices's web management UI by 
utilizing proper packet filtering and/or NAT 

on your router in order to limit network access to your NAS. Although this will 
not completely eliminate the risk of 

exploitation, it becomes substantially more difficult to leverage a successful 
attack, because it would involve either 

a compromise of another host on the victim’s local network or a client side 
attack that overcomes the Same Origin 

Policy restrictions of the victim’s web browser.
We provide an installable package for Sitecom devices that enables browser 
based authentication (Basic Auth) as an 

effective workaround for this and future web management UI vulnerabilities. For 
details refer to 

http://www.alcyon.nl/blog/sitecom-nas-md-253-and-md-254-risk-mitigation/

Vendor responses=
- Sitecom has reported on August 2 that they are working with the manufacturer 
to verify the vulnerability
- Sitecom has confirmed on August 28 that the manufacturer is working on a fix

Fixed Versions=
- There is currently no vendor patch available. 
- A third party patch is provided by Alcyon. See: 
http://www.alcyon.nl/blog/sitecom-nas-md-253-and-md-254-risk-

mitigation/

=Latest version of this advisory
http://www.alcyon.nl/advisories/aa-004/

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