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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2005.0193 -- iDEFENSE Security Advisory 02.25.05 WU-FTPD File Globbing Denial of Service Vulnerability 28 February 2005 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: WU-FTPD Publisher: iDEFENSE Operating System: UNIX variants Impact: Denial of Service Access: Remote/Unauthenticated CVE Names: CAN-2005-0256 Original Bulletin: http://www.idefense.com/application/poi/display?id=207 - --------------------------BEGIN INCLUDED TEXT-------------------- WU-FTPD File Globbing Denial of Service Vulnerability iDEFENSE Security Advisory 02.25.05 www.idefense.com/application/poi/display?id=207&type=vulnerabilities February 25, 2005 I. BACKGROUND WU-FTPD is an ftp daemon for Unix systems developed at Washington University. More information is available at: http://www.wu-ftpd.org/ II. DESCRIPTION Remote exploitation of an input validation vulnerability in version 2.6.2 of WU-FPTD could allow for a denial of service of the system by resource exhaustion. The vulnerability specifically exists in the wu_fnmatch() function in wu_fnmatch.c. When a pattern containing a '*' character is supplied as input, the function calls itself recursively on a smaller substring. By supplying a string which contains a large number of '*' characters, the system will take a long time to return the results, during which time it will be using a large amount of CPU time. III. ANALYSIS After a user logs into the ftpd, an attacker can send a simple command which will cause high CPU utilization. To exploit this vulnerability, a simple ftp client is sufficient. Once logged in, either anonymously or as an authenticated user, issuing the following command will cause the machine to become less responsive. ftp> dir *************************************************************** *************************************************************** *************************************************************** **.* By re-connecting and issuing the command multiple times, the system can be made completely unresponsive. This may prevent legitimate access to services provided by the system for the period of the attack. IV. DETECTION iDEFENSE has confirmed the existence of this vulnerability in version 2.6.2 and 2.6.1 of WU-FTPD. It is suspected that previous versions are also affected by this vulnerability. V. WORKAROUND Consider disabling the ftpd. If this is not viable as an option, consider disabling anonymous access. Disabling anonymous access will not prevent local users from exploiting this vulnerability. VI. VENDOR RESPONSE No vendor response received. VII. CVE INFORMATION The Common Vulnerabilities and Exposures (CVE) project has assigned the names CAN-2005-0256 to these issues. This is a candidate for inclusion in the CVE list (http://cve.mitre.org), which standardizes names for security problems. VIII. DISCLOSURE TIMELINE 02/09/2005 Initial vendor notification - No response 02/18/2005 Initial vendor notification - No response 02/25/2005 Public disclosure IX. CREDIT Adam Zabrocki (pi3 / pi3ki31ny) 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 iQCVAwUBQiKPVih9+71yA2DNAQJ/zgQAg4W/Ry5WKGIeOqo6sM1UnoQDEWTbuybr LhNeW7/1+UYFS5v6XCUKNm/YIhfkUunuv6quw2RJukR/GqaxubVlgtwxxa7WyqZE llf2kNWbbO38RYR8WsEbYJdwn7d3acZKTkOZmgL46TLc8o3vZljEoanUji4kA8xw OhrblO2cRpI= =++6a -----END PGP SIGNATURE-----