Atomic

SUMMARY

This virus infects files that are in the same folder as the virus, and that have the .com extension. This document describes the Atomic virus, and the Atomic.371 and Atomic.480 variants.

Protection

• Virus Definitions (Intelligent Updater) July 28, 1993

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

Atomic
The Atomic virus infects all .com files that are located in the same folder as the virus by appending its viral body to the host. After infecting the files, the virus displays gibberish characters on the screen.

Atomic.371
This variant of Atomic infects all .com files that are located in the same folder as the virus, as well as the C:Command.com file. The virus overwrites the first 371 bytes of the host, which makes it impossible to repair. After infecting the files, the virus displays the message "Program execution terminated."

Atomic.480
This virus is same as Atomic.371, except that the viral body is 480 bytes in length instead of 371 bytes. This virus displays the message "Bad command or file name" instead of "Program execution terminated."

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

To remove this virus:

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. If any files are detected as infected by Atomic, click Repair. If NAV cannot repair the file, you must delete it. Deleted files must be restored from a clean backup.