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SquirrelMail G/PGP Plugin gpg_help.php Local File Inclusion Vulnerability

07.11.07

BACKGROUND

The SquirrelMail G/PGP Encrpytion Plugin is a general purpose encryption, decryption, and digital signature plug-in for SquirrelMail that implements the OpenPGP standard using GPG. More information is available at the following URL.

http://www.squirrelmail.org/plugin_view.php?id=153

DESCRIPTION

Remote exploitation of a local file inclusion vulnerability in version 2.0 of the SquirrelMail G/PGP Plugin could allow an authenticated webmail user to execute arbitrary PHP code under the security context of the running web server.

Version 2.0 of the SquirrelMail G/PGP Plugin contains an implementation flaw in the way it includes certain files. Specifically, the 'gpg_help.php' and 'gpg_help_base.php' files will include local files that are supplied via the 'help' HTTP GET request parameter. An excerpt from the code follows:

 68 // Help body text is inserted here via GET parameter 69 require_once (SM_PATH.'plugins/gpg/help/' . $_GET['help'] ); 

By using directory traversal specifiers, an attacker can trivially cause files stored on the Web server to be parsed as PHP code.

ANALYSIS

Exploitation could allow an attacker to include an arbitrary local file on the affected host.

Due to the lack of input validation on $GET_['help'], directory traversal specifiers could be utilized to parse any file on the system as PHP code.

DETECTION

iDefense has confirmed the existence of this vulnerability in version 2.0 of the G/PGP Encryption Plugin for SquirrelMail. It is suspected that earlier versions of the plug-in are also affected.

WORKAROUND

iDefense is unaware of any available workarounds for this vulnerability.

VENDOR RESPONSE

The maintainers of the SquirrelMail G/PGP plug-in have not responded to repeated inquires regarding this vulnerability. Versions since gpg.2.1devbuild14Jun07 appear to include a fix for this problem. This problem is not present in the recent 2.1 release made on July 7th, 2007.

CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2006-4169 to this issue. This is a candidate for inclusion in the CVE list (http://cve.mitre.org/), which standardizes names for security problems.

DISCLOSURE TIMELINE

08/16/2006 Initial vendor notification
10/06/2006 Second vendor notification
02/16/2007 Third vendor notification
07/11/2007 Public disclosure

CREDIT

The discoverer of this vulnerability wishes to remain anonymous.

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LEGAL NOTICES

Copyright © 2007 Verisign, Inc.

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Disclaimer: The information in the advisory is believed to be accurate at the time of publishing based on currently available information. Use of the information constitutes acceptance for use in an AS IS condition. There are no warranties with regard to this information. Neither the author nor the publisher accepts any liability for any direct, indirect, or consequential loss or damage arising from use of, or reliance on, this information.