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Unchecked Buffer in File Decompression Functions Could Lead to Code Execution (Q329048)

Time: 01:58 EST/06:58 GMT | News Source: Microsoft | Posted By: Byron Hinson

All three vulnerabilities discussed in this bulletin involve the inclusion of the Sun RPC library in Microsoft�s Services for UNIX (SFU) 3.0 on the Interix SDK. Developers who created applications or utilities using the Sun RPC library from the Interix SDK need to evaluate three vulnerabilities.

Zipped files (files having a .zip extension) provide a means to store information in a way that uses less space on a hard disk. This is accomplished by compressing the files that are put into in the zipped file. On Windows 98 with Plus! Pack, Windows Me and Windows XP, the Compressed Folders feature allows zipped files to be treated as folders. The Compressed Folders feature can be used to create, add files to, and extract files from zipped files.

Two vulnerabilities exist in the Compressed Folders function:

An unchecked buffer exists in the programs that handles the decompressing of files from a zipped file. A security vulnerability results because attempts to open a file with a specially malformed filename contained in a zipped file could possibly result in Windows Explorer failing, or in code of the attacker�s choice being run.
The decompression function could place a file in a directory that was not the same as, or a child of, the target directory specified by the user as where the decompressed zip files should be placed. This could allow an attacker to put a file in a known location on the users system, such as placing a program in a startup directory

Patch availability

Download locations for this patch

Windows 98 with Plus! Pack:
http://www.microsoft.com/windows98/downloads/contents/WUCritical/q329048/default.asp
Windows Me:
Only available via Windows Update.
Windows XP:
http://www.microsoft.com/Downloads/Release.asp?ReleaseID=43419