IIS Double Decoding Directory Traversal

Added: 11/28/2005
CVE: CVE-2001-0333
BID: 2708
OSVDB: 556

Background

Microsoft IIS is a web server for Windows platforms.

Problem

Microsoft IIS 4.0 and 5.0 allow path validation checks to be bypassed by URL-encoding invalid characters twice. Thus, a backslash is first represented as %5c, and then %255c. This allows remote attackers to access any executable file on the system using a directory traversal attack from the /scripts virtual directory, leading to command execution.

Resolution

Install the patch referenced in Microsoft Security Bulletin 01-026.

References

http://archives.neohapsis.com/archives/bugtraq/2001-05/0101.html

Limitations

Certain characters are disallowed when using this exploit to run commands.

Platforms

Windows