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Technical Cyber Security Alert TA04-356A
Exploitation of phpBB highlight parameter vulnerability
Original release date: December 21, 2004
Last revised: --
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 fails to
properly perform 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 verison 2.0.11 to prevent exploitation.
Appendix A. References
* US-CERT Vulnerability Note VU#497400 -
<http://www.kb.cert.org/vuls/id/497400>
* phpBB Downloads - < http://www.phpbb.com/downloads.php>
* phpBB Announcement -
<http://www.phpbb.com/phpBB/viewtopic.php?f=14&t=240636>
* Symantec Security Response - Perl.Santy -
<http://securityresponse.symantec.com/avcenter/venc/data/perl.santy
.html>
* McAfee - Computer Virus Software and Internet Security -
<http://us.mcafee.com/virusInfo/default.asp?id=description&virus_k=
130471>
_________________________________________________________________
This vulnerability was reported by the phpBB Development Team.
_________________________________________________________________
Feedback can be directed to the authors: Jeffrey Gennari and
Jason Rafail
_________________________________________________________________
This document is available from:
<http://www.us-cert.gov/cas/techalerts/TA04-356A.html>
_________________________________________________________________
Copyright 2004 Carnegie Mellon University.
Terms of use: <http://www.us-cert.gov/legal.html>
_________________________________________________________________
Revision History
Dec 21, 2004: Initial release
Last updated December 21, 2004
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