Trojan.VirtualRoot

SUMMARY

Trojan.VirtualRoot is a Trojan horse program that is dropped by the CodeRed II and CodeRed.F worms. The Trojan allows a hacker to have full remote access to the Web server that is infected by CodeRed II or CodeRed.F. Norton AntiVirus can detect an infection of CodeRed II or CodeRed.F on a Web server by detecting the payload (Trojan component) of this worm as Trojan.VirtualRoot.

Symantec Security Response has created a tool to perform a vulnerability assessment of your computer and remove the CodeRed Worm, CodeRed II and CodeRed.F. To obtain the CodeRed removal tool, please click here.

Behavior

Symptoms

Transmission

Protection

• Virus Definitions (LiveUpdate™ Weekly) August 4, 2001
• Virus Definitions (Intelligent Updater) August 4, 2001

Threat Assessment

Wild

• Wild Level: Low
• Number of Infections: More than 1000
• Number of Sites: More than 10
• Geographical Distribution: High
• Threat Containment: Moderate
• Removal: Moderate

Damage

• Damage Level: Low
• Compromises Security Settings: Allows remote access to the system.

Distribution

• Distribution Level: Medium

TECHNICAL DETAILS

If Trojan.VirtualRoot has modified the registry key

HKEY_LOCAL_MACHINESystemCurrentControlSet
ServicesW3SVCParametersVirtual Roots

(by adding a few new keys and setting the user group to 217), it allows a hacker to take full control of the Web server by sending an HTTP GET request to run scripts/root.exe on the infected Web server.

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

The CodeRed II worm and the Trojan.VirtualRoot Trojan must be removed together. For removal instructions, please read the Removal section in the CodeRed II or CodeRed.F writeups. You can download a removal tool from here.