Stoned.Michelangelo

The virus copies the original MBR to side 0, cylinder 0, sector 7 on hard drives, logical sector 11 on 360K floppy disks, and logical sector 28 on 1.2 MB floppy disks. Stoned.Michelangelo does not appear to infect 3½-inch floppy disks.

In addition to standard viral replication, Stoned.Michelangelo carries two destructive payloads. The first occurs on floppy disks. If the infected floppy disk contains many directory entries, damage may occur to the last entries in the root directory. This damage appears as a strange filename beginning with three high-bit (high ASCII) characters, followed by the words "MSDOS" or "IBM." These characters are the first part of the floppy disk’s original boot record, which was copied by the virus to a sector near the end of the root directory table. The virus does not check to see if data pre-exists in the target location and, as a result, any data in the target location is overwritten and lost.

The second destructive payload is intentional data destruction on the hard drive. Stoned.Michelangelo triggers on March 6th of every year. If the infected computer is booted at any time on March 6th, the virus silently overwrites the first 17 sectors of the first 256 cylinders of the hard drive with random information from memory. No message or warning is given, although the hard drive light remains on and the system appears to lock up. If the system is immediately turned off, some data may be recoverable. Otherwise, all overwritten areas of the drive are erased beyond recovery by any utility.

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.

Summary