Exploitation of phpBB highlight parameter vulnerability
Original release date: December 21, 2004
Last revised: December 22, 2004
Source: US-CERT
Systems Affected
phpBB versions 2.0.10 and prior
Overview
The software phpBB contains an input validation problem in how it processes a parameter contained in URLs.
An intruder can deface a phpBB website, execute arbitrary commands, or gain administrative privileges on a
compromised bulletin board.
I. Description
phpBB is an open-source bulletin board application. It improperly performs an urldecode() on the "highlight" parameter
supplied to viewtopic.php. This may allow a remote attacker to execute arbitrary commands on a
vulnerable server.
According to reports, this vulnerability is being actively exploited by the Santy.A worm.
The worm appears to propogate by searching for the keyword "viewtopic.php" in order
to find vulnerable sites.
The worm writes itself to a file named "m1ho2of" on the compromised system. It then overwrites files
ending with .htm, .php, .asp. shtm, .jsp, and .phtm replacing them with HTML content that defaces the web page.
The worm then tries to use PERL to execute itself on the compromised system
and propogate further.
US-CERT is tracking this issue as:
VU#497400 -
phpBB viewtopic.php fails to properly sanitize input passed to the "highlight" parameter
II. Impact
A remote attacker may be able to deface a phpBB website and execute arbitrary commands on a compromised bulletin board.
III. Solution
Upgrade phpBB
Upgrade to phpBB version 2.0.11 to prevent exploitation.
Appendix A. References
This vulnerability was reported by the phpBB Development Team.
Feedback can be directed to the authors:
Jeffrey Gennari and Jason Rafail
Copyright 2004 Carnegie Mellon University. Terms of use
Revision History
Dec 21, 2004: Initial release
Dec 22, 2004: Clarified improper use of urldecode()
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