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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2005.0613 -- iDEFENSE Security Advisory 08.09.05 AWStats ShowInfoURL Remote Command Execution 10 August 2005 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: AWStats 6.3 and prior Publisher: iDEFENSE Operating System: UNIX variants Windows Impact: Execute Arbitrary Code/Commands Access: Remote/Unauthenticated CVE Names: CAN-2005-1527 CAN-2005-0436 Original Bulletin: http://www.idefense.com/application/poi/display?id=290 Comment: AWStats vulnerabilities have been actively exploited in the past to compromise and deface large numbers of web servers [1][2]. Given the ease of exploitation and potential for worm-like behaviour, AusCERT recommends following the mitigation steps in this advisory as soon as possible. References: [1] https://www.auscert.org.au/4943 [2] https://www.auscert.org.au/4807 - --------------------------BEGIN INCLUDED TEXT-------------------- AWStats ShowInfoURL Remote Command Execution Vulnerability iDEFENSE Security Advisory 08.09.05 www.idefense.com/application/poi/display?id=290&type=vulnerabilities August 09, 2005 I. BACKGROUND AWStats is a free tool that generates web, streaming, ftp or mail server statistics, graphically. It can analyze log files from all major server tools like Apache log files (NCSA combined/XLF/ELF log format or common/CLF log format), WebStar, IIS (W3C log format) and other web, proxy, wap, streaming servers, mail servers and some ftp servers. More information is available at the vendor's website: http://awstats.sourceforge.net II. DESCRIPTION Remote exploitation of an input validation vulnerability in AWStats allows remote attackers to execute arbitrary commands. AWStats is a logfile analysis tool that generates reports for ftp, mail and web traffic. The problem specifically exists because of insufficient input filtering before passing user-supplied data to an eval() function. As part of the statistics reporting function, AWStats displays information about the most common referrer values that caused users to visit the website. The referrer data is used without proper sanitation in an eval() statement, resulting in the execution of arbitrary perl code. Shown as follows, the $url parameter contains unfiltered user-supplied data that is used in a call to the Perl routine eval() on lines 4841 and 4842 of awstats.pl (version 6.4): my $function="ShowInfoURL_$pluginname('$url')"; eval("$function"); The malicious referrer value will be included in the referrer statistics portion of the AWStats report after AWStats has been run to generate a new report including the tainted data. Once a user visits the referrer statistics page, the injected perl code will execute with permissions of the web service. III. ANALYSIS Successful exploitation results in the execution of arbitrary commands with permissions of the web service. Exploitation will not occur until the stats page has been regenerated with the tainted referrer values from the http access log. Note that AWStats is only vulnerable in situations where at least one URLPlugin is enabled. AWStats is a very commonly used web statistics reporting package. Since this attack does not require special privileges, it is recommended that users update AWStats to the latest available package. IV. DETECTION iDEFENSE Labs has confirmed the existence of this vulnerability in AWStats 6.3. All earlier versions are suspected vulnerable. AWStats 6.4 has been released since the initial research on this vulnerability. AWStats 6.4 has replaced all eval() statements, and has mitigated the exposure to this vulnerability. V. WORKAROUND As a workaround solution, disable all URLPlugins in the AWStats configuration. VI. VENDOR RESPONSE This vulnerability has been addressed with the release of AWStats 6.4. Updated software packages are available from: AWStats 6.4: http://awstats.sourceforge.net/#DOWNLOAD VII. CVE INFORMATION The Common Vulnerabilities and Exposures (CVE) project has assigned the name CAN-2005-1527 to this issue. This is a candidate for inclusion in the CVE list (http://cve.mitre.org), which standardizes names for security problems. It should be noted that this is similar to but different from CAN-2005-0436. VIII. DISCLOSURE TIMELINE 05/12/2005 Initial vendor notification 08/09/2005 Public disclosure IX. CREDIT Peter Vreugdenhil (security[at]petervreugdenhil[dot]nl) is credited with this discovery. Get paid for vulnerability research http://www.idefense.com/poi/teams/vcp.jsp Free tools, research and upcoming events http://labs.idefense.com 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 iQCVAwUBQvlEdyh9+71yA2DNAQL27gP7B00atz/keWmywJ52tE3y9z24cfUh0x8x NR6dHRDJAfQJprEGJEE6Wcgg6VXTYn3iJZmIqiOFq7KgfoSPsUTHviDSGyBc30mR tlBwPabCUg7wbvqemazlY+S1nkcUF8RMB2Ods3LiWSYqiSp8kRQSSaBVyMPNduEf zc4vyqESgk0= =wzaD -----END PGP SIGNATURE-----