EIC.Trojan

SUMMARY

This Trojan horse damages the hard drive boot sector. It is a DOS program that is 68 bytes in length. Parts of the code are very similar to the Standard Antivirus Test File (EICAR).

Protection

• Virus Definitions (Intelligent Updater) June 28, 2001

Threat Assessment

Wild

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

Damage

• Damage Level: Low
• Payload: Corrupts the Boot sector of Hard drive.

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

This file is a Trojan that corrupts the boot sector of a hard drive. To attempt to avoid detection, the Trojan contains code that is very similar to the Standard Antivirus Test File (EICAR). Like one of the EICAR test files, it is 68 bytes in length. This appears to have been done to cause you to believe that it is the test file.

NOTE: Norton AntiVirus detects the true EICAR test file "EICAR Test String.70" or "EICAR Test String.68."

This Trojan calls INT 13, and it uses the call to write junk data to the hard drive boot sector, preventing the computer from booting. It also writes junk data to other sectors of the hard drive, possibly damaging files and folders.

NOTE: This Trojan will not run under Windows NT or 2000.

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. Run LiveUpdate to make sure that you have the most recent virus definitions.
2. Start Norton AntiVirus (NAV), and run a full system scan, making sure that NAV is set to scan all files.
3. Delete any files detected as EIC.Trojan.

NOTE: If the Trojan is executed under Windows 95/98/Me, you probably will not be able to restart the computer. You may have to reformat the hard drive, reinstall Windows and all software, and restore all data from a clean backup.