-----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
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:
February 27, 2004
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
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.
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
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
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
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 email@example.com
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:
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:
Internet Email: firstname.lastname@example.org
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-----
-----END PGP SIGNATURE-----