[UNIX] Discuz! Command Execution Vulnerability

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Discuz! Command Execution Vulnerability
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SUMMARY

<http://www.discuz.net/> Discuz! - "popular web forum applications in
China".

Due to input validation flaw, malicious attackers can cause the Discuz
program to run arbitrary commands with the privilege of the HTTPD process.

DETAILS

Vulnerable Systems:
* Discuz! version 4.0.0 rc4 and prior

Discuz! doesn't properly check multiple extensions of uploaded files,
allowing malicious attackers to upload a file with multiple extensions
such as attach.php.php.php.php.rar to a web server.

This can be exploited to run arbitrary commands with the privilege of the
HTTPD process, which is typically run as the nobody user.

Workaround:
Exclude the RAR extension from the extension list for attached files on an
administration page and wait the release of official patch.

Disclosure Timeline:
* 24.07.05 - Vulnerability found
* 25.07.05 - Vendor notified
* 12.08.05 - Official release

ADDITIONAL INFORMATION

The information has been provided by <mailto:advisory@stgsecurity.com>
SSR Team.

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