Joshi Virus

Virus Name: Joshi Aliases: Happy Birthday Joshi, Stealth Virus V Status: Common Discovered: June, 1990 Symptoms: BSC; machine hangs and message Origin: India Eff Length: N/A Type Code: BRX - Resident Boot Sector/Master Boot Sector Infector Detection Method: ViruScan, NAV, F-Prot, Sweep, AVTK, IBMAV, NAVDX, VAlert, PCScan, ChAV Removal Instructions: NAV, or M-Disk/P General Comments: The Joshi virus was isolated in India in June 1990. At the time it was isolated, it was reported to be widespread in India as well as portions of the continent of Africa. Joshi is a memory resident boot sector infector of diskettes and the hard disk master boot sector (partition table). After a system has been booted from a Joshi-infected diskette, the virus will be resident in memory. Joshi takes up approximately 6K of system memory, and infected systems will show that total system memory is 6K less than is installed if the DOS CHKDSK program is run. Joshi has some similarities to two other boot sector infectors. Like the Stoned virus, it infects the master boot sector of hard disks. Similar to the Brain virus's method of redirecting all attempts to read the boot sector to the original boot sector, Joshi does this with the master boot sector. On January 5th of any year, the Joshi virus activates. At that time, the virus will hang the system while displaying the message: "type Happy Birthday Joshi" If the system user then types "Happy Birthday Joshi", the system will again be usable. This virus may be recognized on infected systems by powering off the system and then booting from a known-clean, write-protected DOS diskette. Using a sector editor or viewer to look at the boot sector of suspect diskettes, if the first two bytes of the boot sector are hex EB 1F, then the disk is infected. The EB 1F is a jump instruction to the rest of the viral code. The remainder of the virus is stored on track 40, sectors 1 through 5 on 360K 5.25 inch Diskettes. For 1.2M 5.25 inch diskettes, the viral code is located at track 80, sectors 1 through 5. It will also be located on the last track of 3.5" diskettes. To determine if a system's hard disk is infected, you must look at the hard disk's master boot sector. If the first two bytes of the master boot sector are EB 1F hex, then the hard disk is infected. The remainder of the virus can be found at cylinder 0, side 0, sectors 2 through 6. The original master boot sector will be located at cylinder 0, side 0, sector 9. The Joshi virus can be manually removed from an infected system by first powering off the system, and then booting from a known-clean, write-protected master DOS diskette. If the system has a hard disk, the hard disk should have data and program files backed up, and the original master boot sector copied back to cylinder 0, side 0, sector 1 from sector 9. Diskettes are easier to remove Joshi from, the DOS SYS command can be used. There are also several disinfector programs available. Systems infected with Joshi may experience problems when attempting to access programs or data files on write protected diskettes. Known variant(s) of Joshi are: Joshi-B: Similar to behavior to the original Joshi virus, the major change with this variant is that when the system is booted on January 5, the boot will hang with no message displayed. If the user types "Happy Birthday Joshi", then the system boot will proceed. Origin: Unknown May, 1992.