Vulnerability Note VU#210148

wget contains directory traversal vulnerability

Overview

The wget utility contains directory traversal vulnerabilities that allow a malicious FTP server to overwrite files on the client host.

I. Description

In a typical file transfer operation, one participant (the client) requests a file while a second participant (the server) provides the requested file. Before processing each request, many server implementations will consult an access control policy to determine whether the client should be permitted to read, write, or create a file at the requested location. If the client is able to craft a request that violates the server's access control policy, then the server contains a vulnerability. Since most vulnerabilities of this type involve escaping a restricted set of directories, they are commonly known as "directory traversal" vulnerabilities.

Directory traversal vulnerabilities are most often reported in server implementations, but recent research into the behavior of FTP clients has revealed vulnerabilities in several file transfer applications, including the wget utility. To exploit these vulnerabilities, an attacker must convince the victim user to access a specific FTP server containing files with crafted filenames. When an affected version of wget attempts to download one of these files, the crafted filename causes the utility to write the downloaded files to the location specified by the filename, not by the victim user. In some cases, the attacker must use a modified FTP server to allow the crafted filenames to be passed to the client.

For more detailed information regarding this research, please read "Directory Traversal Vulnerabilities in FTP Clients", written by Steve Christey.

II. Impact

This vulnerability allows an attacker to mislead wget users, convincing them to unintentionally create or overwrite files on the client's filesystem.

III. Solution

Apply a patch from your vendor

For vendor-specific information regarding vulnerability status and patch availability, please consult the Systems Affected section of this document

Systems Affected

Vendor	Status	Date Updated
Conectiva	Vulnerable	13-Dec-2002
Debian	Vulnerable	13-Dec-2002
Gentoo Linux	Vulnerable	31-Dec-2002
MandrakeSoft	Vulnerable	12-Dec-2002
Red Hat Inc.	Vulnerable	10-Dec-2002
Trustix	Vulnerable	31-Dec-2002

References

http://online.securityfocus.com/archive/1/302956

Credit

The CERT/CC thanks Steve Christey for his discovery and analysis of this vulnerability.

This document was written by Jeffrey P. Lanza.

Other Information

Date Public	12/10/2002
Date First Published	12/10/2002 05:48:29 PM
Date Last Updated	04/14/2003
CERT Advisory
CVE Name	CAN-2002-1344
US-CERT Technical Alerts
Metric	0.68
Document Revision	12

If you have feedback, comments, or additional information about this vulnerability, please send us email.

Get Adobe Reader