SquirrelMail G/PGP Plugin gpg_help.php Local File Inclusion Vulnerability
iDefense Security Advisory 07.11.07
Jul 11, 2007
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.
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.
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.
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.
iDefense is unaware of any available workarounds for this vulnerability.
VI. 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,
VII. 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
VIII. 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
The discoverer of this vulnerability wishes to remain anonymous.
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