The Art of Reversing by Ap0x - Tutoriali.org
The Art of Reversing by Ap0x - Tutoriali.org
The Art of Reversing by Ap0x - Tutoriali.org
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Cracking & BruteForceing<br />
I kao poslednji Nightmare test za ovo izdanje knjige <strong>The</strong> <strong>Art</strong> Of<br />
<strong>Reversing</strong> je posebno napisan jedan jako tezak crackme.<br />
Zadatak:<br />
Mete se nalaze u fajlu ...\Cas12\NAG-Crypto.rar. Ove mete treba reversovati na<br />
sledeci nacin:<br />
1) Crackovati NAG-RAR.exe da biste dobili .rar password za drugi deo<br />
2) Crackovati NAG-Crypto.exe tako da on ne pokazuje NAG (bez otpakivanja)<br />
3) Napisati KeyGenerator za NAG-Crypto.exe fajl!<br />
Srecno!<br />
Resenje: - Korak 1<br />
Nasu prvu metu cemo otvoriti pomocu Ollyja i potrazicemo “Bad Cracker”<br />
string. Njega cemo naci ovde:<br />
Text strings referenced in NAG-RAR:CODE, item 195<br />
Address=00407FA4<br />
Text string=ASCII "Bad Cracker"<br />
Posle dvoklika na ovaj string zavrsavamo ovde:<br />
00407F71 |. 81FA 24030000<br />
00407F77 |. 75 2B<br />
CMP EDX,324<br />
JNZ SHORT NAG-RAR.00407FA4<br />
...<br />
00407FA4 |> 68 24804000 PUSH NAG-RAR.00408024 ; /Text = "Bad Cracker"<br />
Kao sto vidimo ovde cemo zavrsiti ako se izvrsi JNZ skok. Postavicemo jedan<br />
break-point na sam pocetak ovog CALLa. Unecemo kao password 123456789<br />
i pritisnucemo dugme Check. Sa F8 cemo proci kroz kod sve dok ne dodjemo<br />
dovde:<br />
00407D82 |. 8B45 F8 MOV EAX,DWORD PTR SS:[EBP-8] /*Deo 1<br />
00407D85 |. 8A00<br />
MOV AL,BYTE PTR DS:[EAX]<br />
00407D87 |. 8B55 F8<br />
MOV EDX,DWORD PTR SS:[EBP-8]<br />
00407D8A |. 8A52 03<br />
MOV DL,BYTE PTR DS:[EDX+3]<br />
00407D8D |. 32C2<br />
XOR AL,DL<br />
00407D8F |. 8B55 F8<br />
MOV EDX,DWORD PTR SS:[EBP-8]<br />
00407D92 |. 8A52 06<br />
MOV DL,BYTE PTR DS:[EDX+6]<br />
00407D95 |. 32C2<br />
XOR AL,DL<br />
00407D97 |. 25 FF000000 AND EAX,0FF<br />
00407D9C |. 8945 F4 MOV DWORD PTR SS:[EBP-C],EAX */<br />
00407D9F |. 8B45 F8 MOV EAX,DWORD PTR SS:[EBP-8] /* Deo 2<br />
00407DA2 |. 8A40 01<br />
MOV AL,BYTE PTR DS:[EAX+1]<br />
00407DA5 |. 8B55 F8<br />
MOV EDX,DWORD PTR SS:[EBP-8]<br />
00407DA8 |. 8A52 04<br />
MOV DL,BYTE PTR DS:[EDX+4]<br />
00407DAB |. 32C2<br />
XOR AL,DL<br />
00407DAD |. 8B55 F8<br />
MOV EDX,DWORD PTR SS:[EBP-8]<br />
00407DB0 |. 8A52 07<br />
MOV DL,BYTE PTR DS:[EDX+7]<br />
00407DB3 |. 32C2<br />
XOR AL,DL<br />
00407DB5 |. 25 FF000000 AND EAX,0FF<br />
00407DBA |. 8945 EC MOV DWORD PTR SS:[EBP-14],EAX */<br />
00407DBD |. 8B45 F8 MOV EAX,DWORD PTR SS:[EBP-8] /* Deo 3<br />
00407DC0 |. 8A40 02<br />
MOV AL,BYTE PTR DS:[EAX+2]<br />
00407DC3 |. 8B55 F8<br />
MOV EDX,DWORD PTR SS:[EBP-8]<br />
00407DC6 |. 8A52 05<br />
MOV DL,BYTE PTR DS:[EDX+5]<br />
00407DC9 |. 32C2<br />
XOR AL,DL<br />
00407DCB |. 8B55 F8<br />
MOV EDX,DWORD PTR SS:[EBP-8]<br />
00407DCE |. 8A52 08<br />
MOV DL,BYTE PTR DS:[EDX+8]<br />
00407DD1 |. 32C2<br />
XOR AL,DL<br />
00407DD3 |. 25 FF000000 AND EAX,0FF<br />
00407DD8 |. 8945 F0 MOV DWORD PTR SS:[EBP-10],EAX */<br />
<strong>The</strong> <strong>Art</strong> <strong>of</strong> <strong>Reversing</strong> <strong>by</strong> <strong>Ap0x</strong> Page 275 <strong>of</strong> 293
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