VRT Advisories


December 2005 Archive

VRT Rules 2005-12-30

Sourcefire VRT Update

Date: 2005-12-30

Synopsis:

The Sourcefire Vulnerability Research Team (VRT) has learned of multiple vulnerabilities affecting hosts using the Microsoft operating system. The VRT has also learned of a new Sober worm variant that displays uniquely detectable infection characteristics.

Details:

The Microsoft Windows graphics rendering engine does not correctly parse windows metafile (wmf) format files. As a result, viewing a corrupted file may present an attacker with the opportunity to execute code of their choosing.

The Sourcefire VRT has confirmed that a rule identified as sid 2436, released on May 21, 2004, will generate events when an attempt is made to exploit this vulnerability. Also, rules to detect attacks targeting this vulnerability are included in this update and are identified as sids 5318 and 5319.

Note: Due to the possibility of a high false positive rate, sid 5318 is not enabled by default.

WARNING: To reduce the possibility of evasion, http_inspect needs to be configured with "flow_depth 0" so that it can inspect all the traffic from HTTP server responses. Setting flow_depth 0 will cause performance problems in some situations.

The Sober worm is a mass mailer normally spread via email. A variant of this worm displays more infection indicators that can be detected easily using rules.

Rules to detect machines infected with this variant of the sober worm are included in this update and are identified as sids 5321 through 5323.

Rule Pack Summary:

For a complete list of new and modified rules, click here.

Warning:

Sourcefire VRT rule packs often utilize enhancements made to Snort. Operators should upgrade to the latest revision or patch level for Snort to ensure these enhancements are available before using these rules.

About the VRT:

The Sourcefire VRT is a group of leading edge intrusion detection and prevention experts working to proactively discover, assess and respond to the latest trends in hacking activity, intrusion attempts and vulnerabilities. This team is also supported by the vast resources of the open source Snort community, making it the largest group dedicated to advances in network security industry.

Posted by on Dec 30, 2005



VRT Rules 2005-12-14

Sourcefire VRT Update

Date: 2005-12-14

Synopsis:

The Sourcefire Vulnerability Research Team (VRT) has learned of multiple vulnerabilities affecting hosts using the Microsoft operating system.

Details:

Microsoft Security Bulletin MS05-054 A vulnerability exists in the way that Internet Explorer handles COM objects that should not be used by Internet Explorer. When Internet Explorer tries to use these COM objects as ActiveX controls, an attacker may be presented with the opportunity to execute code of their choosing on the target system.

Rules to detect attacks targeting this vulnerability are included in this update and are identified as sids 4890 through 4915.

A vulnerability exists in the way Internet Explorer handles the window() function supplied to the javascript "onload" handler as a parameter. The conditions for exploitation occur when a page is opened in the browser that uses <body onload=window();>

The Sourcefire VRT has confirmed that a rule identified as sid 4647, released on November 9, 2005, will generate events when an attempt is made to exploit this vulnerability.

Rule Pack Summary:

For a complete list of new and modified rules, click here.

Warning:
Sourcefire VRT rule packs often utilize enhancements made to Snort. Operators should upgrade to the latest revision or patch level for Snort to ensure these enhancements are available before using these rules.

About the VRT:

The Sourcefire VRT is a group of leading edge intrusion detection and prevention experts working to proactively discover, assess and respond to the latest trends in hacking activity, intrusion attempts and vulnerabilities. This team is also supported by the vast resources of the open source Snort community, making it the largest group dedicated to advances in network security industry.

Posted by on Dec 14, 2005



VRT Rules 2005-12-08

Sourcefire VRT Certified Rules Update

Date: 2005-12-08

Synopsis:

The Sourcefire Vulnerability Research Team (VRT) has learned of a vulnerability in the Symantec AntiVirus Web Interface. In addition, the Sourcefire VRT has made numerous rule reference additions to existing rules in order to provide users more context for generated events.

Details:

A buffer overflow vulnerability exists in the Symantec AntiVirus Scan Engine Web Service Administrative Interface. The vulnerability exists because user supplied data is not properly checked before processing.

A rule to detect attacks targeting this vulnerability is included in this update and is identified as sid 4681.

The Sourcefire Vulnerability Research Team (VRT) has made numerous rule reference additions to existing rules and has added a number of new rules to provide coverage for additional attack vectors for existing vulnerabilities.

Rule Pack Summary:

For a complete list of new and modified rules, click here.

Warning:

Sourcefire VRT rule packs often utilize enhancements made to Snort. Operators should upgrade to the latest revision or patch level for Snort to ensure these enhancements are available before using these rules.

About the VRT:

The Sourcefire VRT is a group of leading edge intrusion detection and prevention experts working to proactively discover, assess and respond to the latest trends in hacking activity, intrusion attempts and vulnerabilities. This team is also supported by the vast resources of the open source Snort community, making it the largest group dedicated to advances in network security industry.

Posted by on Dec 08, 2005



VRT Rules 2005-12-01

Sourcefire VRT Advisory

Date: 2005-12-02

Synopsis:

The Sourcefire Vulnerability Research Team (VRT) has learned of a Trojan Horse downloader program that uses a vulnerability in the way that Internet Explorer handles a Javascript event as an attack vector.

The Sourcefire VRT has confirmed that a rule identified as sid 4647, released on November 9, 2005, will generate events when an attempt is made to exploit this vulnerability.

Details:

A vulnerability exists in the way Internet Explorer handles the window() function supplied to the javascript "onload" handler as a parameter. The conditions for exploitation occur when a page is opened in the browser that uses <body onload=window();>.

The Delf-DH Trojan downloader uses this vulnerability to exploit vulnerable systems and gives an attacker the ability to download Trojan Horse programs of their choosing onto a vulnerable system.

Detection:

Sourcefire rule packs released on November 9, 2005 contained sid 4647 that will generate events when an attempt is made to exploit this vulnerability.

Note: Sid 4647 is NOT enabled by default, should customers wish to detect attempts to exploit this vulnerability this rule should be enabled. Instructions on how to do this can be found in the product User Guide.

Additional References:

Microsoft Security Advisory (911302)
http://www.microsoft.com/technet/security/advisory/911302.mspx

Microsoft Malicious Software Encyclopedia
http://www.microsoft.com/security/encyclopedia/details.aspx?name=TrojanDownloader:Win32/Delf.DH

About the VRT:

The Sourcefire VRT is a group of leading edge intrusion detection and prevention experts working to proactively discover, assess and respond to the latest trends in hacking activity, intrusion attempts and vulnerabilities. This team is also supported by the vast resources of the open source Snort community, making it the largest group dedicated to advances in network security industry.

Posted by on Dec 01, 2005