TWiki command execution vulnerability

Overview

The TWiki wiki software fails to validate input passed to certain URLs. By accessing a URL containing the TWiki configuration script, an attacker may be able to read arbitrary files.

Description

TWiki is a wiki that is runs in the context of the Apache web server. TWiki is installed by configuring Apache, then accessing a configuration script from a web browser. Before executing the configuration script, the TWiki installation instructions provide a generator for Apache configuration directives that is designed to prevent unauthorized access to the script.

There is a command execution vulnerability in TWiki versions prior to 4.2.3. According to the TWiki download page, this issue can only be exploited if the configure script was not secured as described in step number 8 in the installation guide.

Public exploit code has been released that targets this vulnerability. TWiki servers typically use predictable URLs and vulnerable systems may be found by querying search engines.

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Impact

A remote attacker may be able to execute arbitrary commands or view arbitrary configuration files on a vulnerable system.

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Solution

TWiki versions 4.2.0 and higher

The TWiki team has provided a configuration script to address this issue. The script is available here: <http://twiki.org/p/pub/Codev/TWikiRelease04x02x03/configure&gt;

TWiki versions prior to 4.2.0

See <http://twiki.org/cgi-bin/view/Codev/SecurityAlert-CVE-2008-3195#Hotfix_for_older_TWiki_versions&gt; for more information and refer to step 8 in the Twiki installation guide.

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Make the configure script not executable

Removing, renaming or marking the TWiki configure script (twiki/bin/configure) as not executable will prevent this vulnerability from being exploited.

Restrict access

Restricting access by using a web application or string-matching firewall to block URLs that contain the string /bin/configure may partially mitigate this vulnerability. An example of a string matching rule using iptables is:

iptables -A INPUT -p tcp --dport 80 -m string --string '/bin/configure' --algo bm -j DROP

This workaround is unlikely to be effective in many cases, such as when the server uses the https protocol. This firewall rule should be tested before using on a production system.

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Vendor Information

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TWiki __ Affected

Updated: September 12, 2008

Status

Affected

Vendor Statement

See <http://twiki.org/cgi-bin/view/Codev/TWikiRelease04x02x03#4_2_3_Bugfix_Highlights&gt; for more information.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

CVSS Metrics

Group	Score	Vector
Base
Temporal
Environmental

References

• <http://twiki.org/cgi-bin/view/TWiki/TWikiInstallationGuide#8&gt;
• <http://twiki.org/cgi-bin/view/TWiki.ApacheConfigGenerator&gt;
• <http://twiki.org/p/pub/Codev/TWikiRelease04x02x03/configure&gt;
• <http://twiki.org/cgi-bin/view/Codev/SecurityAlert-CVE-2008-3195#Hotfix_for_older_TWiki_versions&gt;
• <http://www.milw0rm.com/exploits/6269&gt;

Acknowledgements

Thanks to the TWiki team for information that was used in this report.

This document was written by Ryan Giobbi.

Other Information

CVE IDs:	None
Severity Metric:	38.25 Date Public: