From: "Geo." 

WinZip MIME Parsing Buffer Overflow Vulnerability iDEFENSE Security
Advisory 02.27.04a:
http://www.idefense.com/application/poi/display?id=76&type=vulnerabiliti
es
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 _______________________________________________
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