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I hope you understand my terrible english ;-)
Tools...
The first protection
Ok. Enter on command line 'cronos1.exe corbio 123456789012'. CALL [ESP+18] F8 Now we are inside cronos1!: PUSH EBP MOV EBP,ESP PUSH EBX PUSH ESI PUSH EDI CALL 0041074 ;Important! Its redirection call. F8Trace down until you get: 0041012C: CALL 004100E7 ; STRLEN POP ECX CMP EAX,06 JL 00410176 ; IF length_of_the_name < 6 ; THEN GO_OUT! PUSH EDI CALL 004100E7 POP ECX CMP EAX,0C ; IF LENGTH_OF_THE_SERIAL < 12 ; THEN GO_OUT! JL 00410176 XOR ECX,ECX MOV EDX,EDI MOV EAX,ESI 00410149: MOVSX ESI,BYTE PTR [EAX] MOVSX EDI,BYTE PTR [EAX] IMUL ESI,EDI MOVSX EDI,BYTE PTR [EDX] ADD ESI,EDI MOVSX EDI,BYTE PTR [EDX+6] ADD EDI,-60 IMUL EDI,EDI,1A ADD ESI,EDI ADD ESI,-60 OR EBX,ESI INC ECX INC EDX INC EAX CMP ECX,06 JL 00410149 here: CMP EBX,01 ;for correct name/serial EBX=0. ;Can you code the KeyGen now? ;I can :)) SBB EBX, EBX NEG EBXThe second protection >>I will let you deduce the second protection from there.
Ok. Lets start our deduce ;) 004101F3: MOV [EDX],CL ;store INC EDI INC EDX INC EAX MOV CL,[EAX]d eax Some strings. Do you know what it is? It's environment block. (see GetEnvironventStrings in Win32 SDK Reference Help) TEST CL,CL JZ 00410203 CMP EDI,06 JZ 004101F3 .......... 0041020F: MOV EAX,[EBP-0C] ; for correct: EAX=41455244 'DREA' MOV EDX,[EBP-08] ; for correct: EDX=0000534D 'MS' ; DREAMS ;) IMUL ECX,EAX,00DA7949 MOV EAX,ECX IMUL ECX,EDX,2262AD4D MOV EDX,ECX CMP EAX,6E8E9964 JNZ 00410270 CMP EDX, 55DE1729 JNZ 00410270 PUSH ESI CALL 004100E7 ;STRLEN POP ECX CMP EAX,0C ; if length_environment_string < 12 ; then go_out! .............. ..............And some checks for our environment string: At the end of checks we understand - our string should be DREAMS\DARES Lets do it. On command line: 'set DDREAMS\DARES=CORBIO[GC]' ;) If you know correct name/serial - start the program: "Cronos Says - Registered" :)
Yes! I do it. hehe
Greets to...
Corbio
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