W95.BlueCorners.2049

1. It starts by running the host program in a separate process.
2. Next, it infects all .exe files on the same drive as the virus, and on the C drive (if the virus is located elsewhere.)
   
   NOTES:
   • This virus does not become memory-resident, but it does use a memory location allocated to the operating system to indicate whether to infect the system or not. This simply means that the virus will only try to infect files once, after the system has been rebooted.
   • Some systems may crash randomly, since this memory location is intended for use by the system. This virus also uses this memory location in such a fashion that if more than 4 logical drives are hooked to the system, then it will try to infect files every time that it is activated.
3. When it is finished infecting files, this virus checks if the date is one of the following:
   • January 1
   • February 14
   • April 1
   • May 4
   • October 1
   • December 25

If it is, it activates its payload routine, which animates a number of small blue balls in the four corners of the screen (one corner is shown in the following picture).



The payload assumes that the screen resolution is 800x600 so that , depending on the resolution, the upper right corner, lower right corner and lower left corner balls may appear elsewhere.

Recommendations

Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

• Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
• 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.
• Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
• Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
• Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
• Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
• If a 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.
• Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
• Isolate compromised computers quickly to prevent threats from spreading further. 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.
• If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
• For further information on the terms used in this document, please refer to the Security Response glossary.