Protect yourself against future threats.
-----BEGIN PGP SIGNED MESSAGE----- =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2004.0173 -- iDEFENSE Security Advisory 02.27.04a WinZip MIME Parsing Buffer Overflow Vulnerability 01 March 2004 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: WinZip 9.0 beta WinZip 8.1 SR-1 Publisher: iDEFENSE Operating System: Windows Impact: Execute Arbitrary Code/Commands Access Required: Remote - --------------------------BEGIN INCLUDED TEXT-------------------- WinZip MIME Parsing Buffer Overflow Vulnerability iDEFENSE Security Advisory 02.27.04a: http://www.idefense.com/application/poi/display?id=76&type=vulnerabilities February 27, 2004 I. BACKGROUND WinZip is an archiving utility for the Microsoft Windows platform featuring built-in support for CAB files and for popular Internet file formats such as TAR, gzip, UUencode, BinHex, and MIME. ARJ, LZH, and ARC files are supported via external programs. More information is available at http://www.winzip.com. II. DESCRIPTION Exploitation of a buffer overflow vulnerability within a parameter parsing routine of WinZip Computing Inc.'s WinZip Archive Utility for Windows allows remote attackers to execute arbitrary code. The problem specifically exists in the UUDeview package which is used to support various decoding routines. When providing long strings to certain parameters of MIME archives (.mim, .uue, .uu, .b64, .bhx, .hqx and .xxe extensions) WinZip will crash referencing an "internal error in file misc.c line 132". Analysis of the log file created by WinZip upon crash reveals that exploitation is plausible: Return address = 0041a923 Return address = 0044c06c Return address = 41414141 Further analysis reveals that WinZip is crashing due to an invalid reference at the following instruction: 0049c332: mov dword ptr [ecx+08], edi Both the ecx and edi registers in the above instruction are user controllable allowing an attacker to craft a MIME archive that upon opening will execute arbitrary code. III. ANALYSIS Successful exploitation requires that an attacker convince a target user to open a malicious MIME archive. The target user must have a vulnerable version of WinZip installed which by default includes a handler for the one of the vulnerable file types. Example methods of propagation include e-mail, web links and P2P software. iDEFENSE has proof of concept exploit code demonstrating the impact of this vulnerability. IV. DETECTION iDEFENSE has confirmed the existence of this vulnerability in WinZip 8.1 SR-1 (the latest stable version) and the latest beta release of WinZip 9.0. It is suspected that earlier versions are vulnerable as well. V. WORKAROUND User awareness is the best method of defense against this class of attack. Users must be wary when opening attachments or following links from untrusted sources. Removal of the extension handler for vulnerable file types can prevent exploitation from double clicking on what may appear to be a harmless WinZip archive. This can be accomplished by opening Windows Explorer, selecting "Tools", then "Folder Options", selecting the "File Types" tab, scrolling to MIM and deleting the appropriate entry. VI. VENDOR FIX This issue has been addressed in WinZip 9.0, available at http://www.winzip.com/. VII. CVE INFORMATION A Mitre Corp. Common Vulnerabilities and Exposures (CVE) number has not yet been assigned. VIII. DISCLOSURE TIMELINE January 13, 2004 Vulnerability acquired by iDEFENSE February 9, 2004 Initial vendor notification February 9, 2004 Initial vendor response February 10, 2004 iDEFENSE clients notified February 27, 2004 Coordinated public disclosure - --------------------------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. 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 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 iQCVAwUBQEKacCh9+71yA2DNAQEqwwP6A0BGbrgCvk5TKXQmOjD1BxNYk7ojkYwn e5tNtVrmdzngcwXT8gnDEAi8puclofwe0vdLR8GnusodXU62vGrArAIK4n4+Yl2w KwcVORIzgrcFwSDCXOw7bPdSZNVHehiHGbIGNqQfW8ikWqvCbio6WKMPxmyZ+DUf O6Zzv5bYH2Q= =OAT/ -----END PGP SIGNATURE-----