W32.Giri

SUMMARY

W32.Giri is a Windows virus which infects 32-bit Windows executables (PE files).

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
• Payload: Three months after infection, the virus will trigger one of four payloads. The virus creates the file C:GIRIGAT.BMP and sets it as the Windows wallpaper. The virus moves the current mouse cursor position and causes the current application to stop. The virus changes the Windows copyright information in the System Info dialog. The virus attempts to continuously open and close the CD ROM tray. Variant Information An executable has been discovered, which drops the W32.Giri virus onto your system. This executable is detected as W32.Giri.G1 (first generation) as of September 10, 1999.

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

W32.Giri is a simple appending Windows virus adding its code to the last section of the file. When executed, the virus attempts to infect PE EXE files in both the current directory and the Windows directory. The virus also goes memory resident infecting files when accessed however, only remains memory resident as long as the host program is running. When the host program is terminated, the virus will no longer be in memory.

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.