Hello Guys,
i am reversing a malware sample .but getting stucked in a loop below.the line writeen in the bold letter generated random letter like "/2","/lm32" etc to EDX.The thing is that ECX doesnot contains any contents memory ,so only register address will be added
004011F7 > 8BD4 MOV EDX,ESP
004011F9 . 03E1 ADD ESP,ECX
004011FB . 4C DEC ESP
004011FC . 66:8B3C24 MOV DI,WORD PTR [ESP]
00401200 . 8BE2 MOV ESP,EDX
00401202 . 8BD6 MOV EDX,ESI
00401204 . 03D1 ADD EDX,ECX
00401206 . 50 PUSH EAX
00401207 . 03C2 ADD EAX,EDX
00401209 . 2D 01000000 SUB EAX,1
0040120E . 81E7 FFFF0000 AND EDI,0FFFF
00401214 . 52 PUSH EDX
00401215 . 8BD7 MOV EDX,EDI
00401217 . 8810 MOV BYTE PTR [EAX],DL
00401219 . 5A POP EDX
0040121A . 58 POP EAX
0040121B . 49 DEC ECX
0040121C . 83F9 00 CMP ECX,0
0040121F . 0F84 02000000 JE test.00401227
00401225 .^ EB D0 JMP SHORT test.004011F7
i am adding the below screenshots before stepin and afetr stepout.
please let me know what is happening there
i am reversing a malware sample .but getting stucked in a loop below.the line writeen in the bold letter generated random letter like "/2","/lm32" etc to EDX.The thing is that ECX doesnot contains any contents memory ,so only register address will be added
004011F7 > 8BD4 MOV EDX,ESP
004011F9 . 03E1 ADD ESP,ECX
004011FB . 4C DEC ESP
004011FC . 66:8B3C24 MOV DI,WORD PTR [ESP]
00401200 . 8BE2 MOV ESP,EDX
00401202 . 8BD6 MOV EDX,ESI
00401204 . 03D1 ADD EDX,ECX
00401206 . 50 PUSH EAX
00401207 . 03C2 ADD EAX,EDX
00401209 . 2D 01000000 SUB EAX,1
0040120E . 81E7 FFFF0000 AND EDI,0FFFF
00401214 . 52 PUSH EDX
00401215 . 8BD7 MOV EDX,EDI
00401217 . 8810 MOV BYTE PTR [EAX],DL
00401219 . 5A POP EDX
0040121A . 58 POP EAX
0040121B . 49 DEC ECX
0040121C . 83F9 00 CMP ECX,0
0040121F . 0F84 02000000 JE test.00401227
00401225 .^ EB D0 JMP SHORT test.004011F7
i am adding the below screenshots before stepin and afetr stepout.
please let me know what is happening there
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