Trojan.Badcon

SUMMARY

Trojan.Badcon is a Trojan horse that can cause unpatched Windows 95/98/98SE systems to crash and force a restart. The Trojan may present itself as a valid program, such as X-Box emulation software.

Protection

• Virus Definitions (Intelligent Updater) January 14, 2002

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: Medium
• Payload Trigger: Running Trojan.Badcon
• Causes System Instability: Crashes unpatched Windows95, Windows98, and Windows98 SE to the extend that the machine must be restarted.

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

This Trojan horse takes advantage of an old Windows 95/98 vulnerability. A Microsoft patch that fixes this vulnerability has been available since March 2000. The affected systems are Windows 95, Windows 98 and Windows 98 Second Edition (SE).

For details about this vulnerability and the patch, read the Microsoft Security Bulletin (MS00-017).

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

NOTE: Virus definitions that can detect and remove Trojan.Badcon will be included in virus definitions dated January 16, 2002. The instructions that follow assume that you are performing this removal on or after the date that these definitions have been released. To provide information on new threats as quickly as possible, in some cases, virus writeups are published before the actual definitions are released to the public.

If you suspect that the computer is infected with Trojan.Badcon, but it has not been detected by Norton AntiVirus, submit the suspect file or files to Symantec Security Response using Scan and Deliver. See the document How to submit a file to Symantec Security Response using Scan and Deliver. If Symantec Security Response determines that the file is infected by a threat for which definitions have not yet been released, you may receive a file by return email that contains "Beta" definitions for the threat. Detach and execute the file to install the updated definitions, and then continue with the instructions in this document.

1. Run LiveUpdate to make sure that you have the most recent virus definitions.
2. Start Norton AntiVirus (NAV), and make sure that NAV is configured to scan all files. For instructions on how to do this, read the document How to configure Norton AntiVirus to scan all files.
3. Run a full system scan.
4. Delete all files that are detected as Trojan.Badcon.