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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2005.0112 -- iDEFENSE Security Advisory 02.07.05 SquirrelMail S/MIME Plugin Command Injection Vulnerability 8 February 2005 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Squirrelmail Publisher: iDEFENSE Operating System: Linux variants UNIX variants Windows Impact: Execute Arbitrary Code/Commands Access: Existing Account Original Bulletin: http://www.idefense.com/application/poi/display?id=191 Comment: SquirrelMail is capable of running on a range of web servers that support PHP. The impact of this vulnerability may therefore vary with the configuration of your web server and the user context it runs in. - --------------------------BEGIN INCLUDED TEXT-------------------- SquirrelMail S/MIME Plugin Command Injection Vulnerability iDEFENSE Security Advisory 02.07.05 www.idefense.com/application/poi/display?id=191&type=vulnerabilities February 07, 2005 I. BACKGROUND Squirrelmail S/MIME plugin enables the viewing of S/MIME-signed messages of the MIME "multipart/signed" format. More information about the plugin is available at: http://www.squirrelmail.org/plugin_view.php?id=54 II. DESCRIPTION Remote exploitation of a command injection vulnerability in the Squirrelmail S/MIME plugin allows web mail users to execute arbitrary commands with the privileges of the web server. The problem specifically exists due to insufficient filtering of user-provided data in a call to exec(). The following snippet exposes the offending area of code from viewcert.php: if(!isset($cert)) $cert=$_GET['cert']; ... function x509_open($cert) { global $cert_in_dir, $openssl; $lines = array(); exec("$openssl x509 -in $cert_in_dir$cert -subject -issuer \ -dates -serial -fingerprint -noout 2>/tmp/err", $lines); ... list ($ow, $is, $nb, $na, $sn, $fp) = x509_open($cert); The variable '$cert' from the above snippet contains unfiltered user supplied data and can be exploited. III. ANALYSIS Successful exploitation allows authenticated web mail users to execute arbitrary commands on the underlying system with the privileges of the web server. This can lead to further compromise and exposure of other users' mail to the attacker. IV. DETECTION iDEFENSE has confirmed the existence of this vulnerability in S/MIME plugin 0.5 and 0.4. Earlier versions are also suspected to be vulnerable. V. WORKAROUND PHP provides the escapeshellarg() routine to filter data to be used as an argument to calls such as exec() and system(). Modify the call to exec() from: exec("$openssl x509 -in $cert_in_dir$cert -subject -issuer -dates \ -serial -fingerprint -noout 2>/tmp/err", $lines); To: $filtered = escapeshellarg("$cert_in_dir$cert"); exec("$openssl x509 -in $filtered -subject -issuer -dates -serial \ -fingerprint -noout 2>/tmp/err", $lines); VI. VENDOR RESPONSE The vendor has released S/MIME plugin 0.6 to address this vulnerability. The plugin is available for download at: http://www.squirrelmail.org/plugin_view.php?id=54 VII. CVE INFORMATION A Mitre Corp. Common Vulnerabilities and Exposures (CVE) number has not been assigned yet. VIII. DISCLOSURE TIMELINE 09/22/2004 Initial vendor notification 09/22/2004 Initial vendor response 02/07/2005 Coordinated public disclosure IX. CREDIT Karol Wiesek is credited with this discovery. Get paid for vulnerability research http://www.idefense.com/poi/teams/vcp.jsp X. LEGAL NOTICES Copyright (c) 2005 iDEFENSE, Inc. Permission is granted for the redistribution of this alert electronically. It may not be edited in any way without the express written consent of iDEFENSE. If you wish to reprint the whole or any part of this alert in any other medium other than electronically, please email customerservice@idefense.com for permission. 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. - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. If you do not know who that is, please send an email to auscert@auscert.org.au and we will forward your request to the appropriate person. NOTE: Third Party Rights This security bulletin is provided as a service to AusCERT's members. As AusCERT did not write the document quoted above, AusCERT has had no control over its content. The decision to follow or act on information or advice contained in this security bulletin is the responsibility of each user or organisation, and should be considered in accordance with your organisation's site policies and procedures. AusCERT takes no responsibility for consequences which may arise from following or acting on information or advice contained in this security bulletin. NOTE: This is only the original release of the security bulletin. It may not be updated when updates to the original are made. If downloading at a later date, it is recommended that the bulletin is retrieved directly from the author's website to ensure that the information is still current. Contact information for the authors of the original document is included in the Security Bulletin above. If you have any questions or need further information, please contact them directly. Previous advisories and external security bulletins can be retrieved from: http://www.auscert.org.au/render.html?cid=1980 If you believe that your computer system has been compromised or attacked in any way, we encourage you to let us know by completing the secure National IT Incident Reporting Form at: http://www.auscert.org.au/render.html?it=3192 =========================================================================== Australian Computer Emergency Response Team The University of Queensland Brisbane Qld 4072 Internet Email: auscert@auscert.org.au Facsimile: (07) 3365 7031 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AusCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). On call after hours for member emergencies only. =========================================================================== -----BEGIN PGP SIGNATURE----- Comment: http://www.auscert.org.au/render.html?it=1967 iQCVAwUBQggYDSh9+71yA2DNAQJCoAP/d55tUuF5+w8p26xBzHt500nQBrjg8mcz gTa0L0yh6+jCpj2WxC8LTdaWvj446IH+y0ERnJ8ZWTKKnbxhYbE5stHHZCo6dOT9 TvNXQtnvwG2Upv5+PfeUobUIXrWBcvISrhUH7rsdtDIu4GpN7kYqPDrGBvA8hwXm 9vpCY80fYjI= =ze1n -----END PGP SIGNATURE-----