Summary

Wyx is a not dangerous memory resident encrypted boot virus. The virus code consists of two disk sectors. The virus infects the MBR of the hard drive, the C: drive boot sector and boot sector on floppy disks. The MBR of the hard drive gets infection on booting from an infected floppy disk. To infect other drives the virus hooks INT 8 (timer) and with delays checks if other drives are in use, and depending on that infects either drive A:, or drive B:, or boot sector if the C: drive.

While infecting the MBR sector the virus disables Virus protection by resetting necessary field in the CMOS memory. The original MBR, boot sector of the C: drive and second virus sector are stored in the last sectors of the hard drive first track (reserved track), the original boot sector of floppy drives is stored at the end of root directory sectors.

The virus does not manifest itself in any way. It contains the following text:

 31/03/98 WYX

[Analysis: Kaspersky Labs]