DeepThroat.Trojan

SUMMARY

DeepThroat.Trojan has no visual indicators of infection. When executed, this Trojan horse modifies the system registry to enable itself to run as a service. When installed on a Microsoft Windows system, it lets others gain full access to the system through a network connection.

Behavior

Symptoms

Transmission

Protection

• Virus Definitions (Intelligent Updater) May 15, 2000

Threat Assessment

Wild

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

Damage

• Damage Level: Low
• Payload: Modifies registry keys
• Releases Confidential Info: Dial-up passwords and system information
• Compromises Security Settings: Unauthorized users may have access to your system

Distribution

• Distribution Level: Low
• Target of Infection: Microsoft Windows 9x and NT Machines

TECHNICAL DETAILS

This Trojan horse opens a large number of ports for listening. It can be used to allow unauthorized access to your computer.

The file name of the attachment might vary. When executed, the Trojan horse sets the path and file name of the attachment (usually c:windows empfilename.exe) equal to the "SystemDLL32" value in following registry key:

HKLMSoftwareMicrosoftWindowsCurrentVersionRun

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

1. Scan your computer with Norton AntiVirus.
2. Restart your computer in MS-DOS mode.
3. Delete any files detected by Norton AntiVirus as DeepThroat.Trojan.
4. Restart the system.
5. Edit the Windows registry using Regedit.exe. Go to the following registry key:
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun
   
6. On the right side of the window, look for the registry entry with SystemDLL32 as its name field. Right-click SystemDLL32 and click Delete.
7. Restart the machine again, look at the registry, and make sure that the Trojan horse did not reinstall itself.