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-
- Date: Thu, 18 Oct 90 19:17:54 -0400
- From: MMCCUNE@sctnve.bitnet
- Subject: Removing Joshi virus (PC)
-
- I would like to thank the members of the Virus-L, Fidonet and
- Interlink virus conferences for there feedback on this program.
- Earlier, I posted a remover for the Joshi Virus that didn't check
- for the virus before trying to remove it. I have now added several
- checks to the new version of the program....
-
- mov ah,0h
- mov dx,80h
- int 13h ;Reset hard disk
- mov cx,1h
- mov bx,200h
- mov ax,201h
- int 13h ;Load sector 1 of partition table into memory
- or ah,ah ;Check for a read error
- jnz read_error
- es:
- cmp w[bx],1feb ;See if partition table is infected
- jnz no_virus
- mov cx,000ah
- mov ax,301h
- int 13h ;Save copy of partition record
- or ah,ah ;See if there was a write error
- jnz write_error
- mov cx,9h
- mov ax,201h
- int 13h ;Load sector 9 of partition table into memory
- or ah,ah ;Check for a read error
- jnz read_error
- cmp w[bx+1fe],0aa55h ;Checks for a valid partition record
- jnz no_remove
- mov cx,1h
- mov ax,301h
- int 13h ;Write sector 9 over sector 1 (in partition table)
- or ah,ah ;Check for a write error
- jnz write_error
- mov ah,9h
- lea dx,remove_message
- int 21h
- int 20h
- no_virus:
- mov ah,9h
- lea dx,virus_message
- int 21h
- int 20h
- no_remove:
- mov ah,9h
- lea dx,no_remove_message
- int 21h
- int 20h
- read_error:
- mov ah,9h
- lea dx,read_message
- int 21h
- int 20h
- write_error:
- mov ah,9h
- lea dx,write_message
- int 21h
- int 20h
- remove_message:
- db 'Joshi Removed$'
- virus_message:
- db 'Joshi not found$'
- no_remove_message:
- db 'Joshi can not be removed!$'
- read_message:
- db 'Read Error$'
- write_message:
- db 'Write Error$'
-
- This program will remove the Joshi virus from the hard disk.
- McAfee's SCANV64 or above will detect it. The virus can also be
- detected by looking at the partition table with a HEX editor such as
- Norton Utilities. First, cold boot (turn the machine off) off a
- clean, write protected diskette. Then look at the partition record
- (Track 0, Head 0, Sector 1). If the first two bytes are Hex EB 1F,
- the hard disk is infected.
-
- The virus also does some other things to make itself detectable.
- When the date is set to 1-05-(any year), a green screen with the
- words "TYPE HAPPY BIRTHDAY JOSHI" appear on the screen. The machine
- will halt until the message is typed.
-
- Also, CHKDSK will show 6k less memory than is available on an
- unifected system .
-
- Probably the most annoying bug in the virus is that it won't allow
- you to format a diskette while it is active in memory; the system
- will give a "bad track 0" error.
-
- To use, first boot off an unifected diskette (this is very
- important). Then type RMJOSHI. This will remove the virus from the
- hard disk. It will leave traces of the virus in the partition table
- but the virus will be disabled and the system will be returned to
- normal.
-
- RMJOSHI will give four messages:
-
- Joshi Removed - The virus was found and removed from the partition
- table of the hard disk. Joshi not found - Either the virus is
- active in memory or the hard disk is not infected. Joshi can not -
- Either the partition record is corrupted or you have a new be
- removed variation of the virus.
-
- Read Error - The program aborted because there was an error
- reading the hard disk.
-
- Write Error - The program aborted because there was an error
- writing to the hard disk.
-
- When dealing with viruses, there is always a danger of losing
- programs or data. Thus, I offer no warranty on these programs. They
- may be freely distributed as long as they are not altered in any
- way. I can be reached on the FIDONET virus echo, the INTERLINK
- virus echo and VIRUS-L digest. I can also be reached on BITNET as
- MMCCUNE@SCT.NVE. It is free to use by all private individuals
- (Institutions please contact me first).
-
- Mike McCune.
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