Crazy_Boot

SUMMARY

Crazy_Boot is a virus that causes no intentional, permanent damage. However, if the host computer is booted from an infected floppy disk, Crazy_Boot makes it appear that all physical hard drives have been lost. Crazy_Boot spreads to unprotected disks easily. It spreads only on diskettes, not by file distribution.

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
• Target of Infection: DOS floppy boot sectors and master boot records

TECHNICAL DETAILS

Crazy_Boot resides in memory. It infects the master boot records of all physical hard disks and infects the boot sectors of floppy disks. If Crazy_Boot is in memory, any access to the boot record is rerouted to a copy of the original boot sector.

When Crazy_Boot infects a hard drive, it makes a copy of the partition table (an important part of the system area), writes the copy of the partition table to decimal-offset by 256 (100 hexadecimal), and deletes the original partition table. To read the partition information (and see the drive), Crazy_Boot must be active in memory. If users boot from a virus-free floppy disk to avoid Crazy_Boot, all physical hard drives are inaccessible by normal means. In addition, Crazy_Boot writes portions of its viral code to cylinder 0, side 0, sectors 4 and 5.

After 8,995 disk reads, the following text string is printed to the screen:

Dont PLAY with the PC! Otherwise you will get in DEEP,DEEP trouble. Crazy Boot Ver. 1.0

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.