Bloodhound.Exploit.6

SUMMARY

Bloodhound.Exploit.6 is a heuristic detection for exploits of a Microsoft Internet Explorer vulnerability. This vulnerability was discovered in February 2004.

The vulnerability results from the incorrect handling of HTML files embedded in CHM files. (CHM is the Microsoft-compiled HTML help format.)

For more information, and to download a patch for the vulnerability, read Microsoft Security Bulletin MS04-013.

Behavior

Symptoms

Transmission

Protection

• Virus Definitions (LiveUpdate™ Weekly) February 13, 2004
• Virus Definitions (Intelligent Updater) February 13, 2004

Threat Assessment

Wild

• Wild Level: Low
• Number of Infections: 0 - 49
• Number of Sites: 0 - 2
• Geographical Distribution: Low
• Threat Containment: Easy
• Removal: Easy

Damage

• Damage Level: Low

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

By embedding a specially crafted URL in a Web page and having that URL refer to a CHM file containing an HTML file with scripts in it, an attacker could force the user who views the Web page with a vulnerable version of Internet Explorer to download and execute files.

Recommendations

Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

• Turn off and remove unneeded services. By default, many operating systems install auxiliary services that are not critical, such as an FTP server, telnet, and a Web server. These services are avenues of attack. If they are removed, blended threats have less avenues of attack and you have fewer services to maintain through patch updates.
• If a blended threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
• Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services (for example, all Windows-based computers should have the current Service Pack installed.). Additionally, please apply any security updates that are mentioned in this writeup, in trusted Security Bulletins, or on vendor Web sites.
• Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
• Configure your email server to block or remove email that contains file attachments that are commonly used to spread viruses, such as .vbs, .bat, .exe, .pif and .scr files.
• Isolate infected computers quickly to prevent further compromising your organization. Perform a forensic analysis and restore the computers using trusted media.
• Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.

REMOVAL

This is a detection for exploits of a Microsoft Internet Explorer vulnerability, so it therefore does not need to be removed in the same manner as a virus or worm.

It is important that you apply the patch for the vulnerability as described in Microsoft Security Bulletin MS04-013. Once patched, the system is no longer be vulnerable to the exploit.

If the exploit has run on your system, it is possible that some HTML files remain on the infected computer, even after the system was patched against the vulnerability.

The most likely place to find such files are the Internet Explorer Temporary Internet Files and cookies. If you are still getting detections after applying the patch, the files should be deleted. See the Additional Information section for instructions.