这个crackme 是tkm 2004年的strainer,用ECC保护的。虽然ECC大家玩得比较熟了,不过这个东东的保护方法还是有点意思。
用PEiD查壳并脱壳,unpack不是目的,算法才是关键。unpack后载入ida,用miracl的sig,或
http://www.secretashell.com/cryptocrk/tutorials/miracl.calls.zip这里的方法识别miracl库函数,检查序列号的流程一目了然。
1.获取name,sn1,sn2
Un_FSG__:0040194C loc_40194C:
Un_FSG__:0040194C push 50h
Un_FSG__:0040194E push offset name
Un_FSG__:00401953 push 2
Un_FSG__:00401955 push edi
Un_FSG__:00401956 call GetDlgItemText ; name>=4
Un_FSG__:0040195B mov esi, eax
Un_FSG__:0040195D push 50h
Un_FSG__:0040195F push offset sn1
Un_FSG__:00401964 push 3
Un_FSG__:00401966 push edi
Un_FSG__:00401967 call GetDlgItemText ; sn1>=4
Un_FSG__:0040196C mov ebx, eax
Un_FSG__:0040196E push 50h
Un_FSG__:00401970 push offset sn2
Un_FSG__:00401975 push 4
Un_FSG__:00401977 push edi
Un_FSG__:00401978 call GetDlgItemText ; sn2>=1
Un_FSG__:0040149C call epoint_init
Un_FSG__:004014A1 mov edi, eax
Un_FSG__:004014A3 mov [esp+1F8h+var_1F8], 0
Un_FSG__:004014AA call _mirvar
Un_FSG__:004014AF mov [ebp+pt2_x], eax
Un_FSG__:004014B5 call epoint_init
Un_FSG__:004014BA mov [esp+1F8h+var_1F8], 0
Un_FSG__:004014C1 mov [ebp+pt2], eax
Un_FSG__:004014C7 call _mirvar
Un_FSG__:004014CC mov [ebp+big_t], eax
Un_FSG__:004014D2 call epoint_init
Un_FSG__:004014D7 mov [ebp+pt3], eax
Un_FSG__:004014DD call epoint_init
Un_FSG__:004014E2 mov [ebp+pt4], eax
Un_FSG__:004014E8 call epoint_init
Un_FSG__:004014ED mov dword ptr [esi+220h], 10h
Un_FSG__:004014F7 mov [ebp+pt5], eax
...
Un_FSG__:00401512 mov ebx, [ebp+a]
Un_FSG__:00401518 push offset a416d656e657369 ; "416D656E65736961"
Un_FSG__:0040151D push ebx
Un_FSG__:0040151E call _cinstr
Un_FSG__:00401523 pop eax
Un_FSG__:00401524 pop edx
Un_FSG__:00401525 mov eax, [ebp+b]
Un_FSG__:0040152B push offset a1b35b7093fee5a ; "1B35B7093FEE5AE601A"
Un_FSG__:00401530 push eax
Un_FSG__:00401531 call _cinstr
Un_FSG__:00401536 pop ebx
Un_FSG__:00401537 pop esi
Un_FSG__:00401538 mov esi, [ebp+p]
Un_FSG__:0040153E push offset aFffffffdffffff ; "FFFFFFFDFFFFFFFFFFFFFFFFFFFFFFFF"
Un_FSG__:00401543 push esi
Un_FSG__:00401544 call _cinstr
Un_FSG__:00401549 pop eax
Un_FSG__:0040154A pop edx
Un_FSG__:0040154B mov edx, [ebp+pt1_x]
Un_FSG__:00401551 push offset a71263a72c2fdfb ; "71263A72C2FDFB8FE851182B408210A4"
Un_FSG__:00401556 push edx
Un_FSG__:00401557 call _cinstr
Un_FSG__:0040155C mov eax, [ebp+pt2_x]
Un_FSG__:00401562 pop ecx
Un_FSG__:00401563 pop ebx
Un_FSG__:00401564 push offset a2c052124bdd94e ; "2C052124BDD94E5645E99B01DCECA28D"
Un_FSG__:00401569 push eax
Un_FSG__:0040156A call _cinstr
Un_FSG__:0040156F mov eax, [ebp+p]
Un_FSG__:00401575 push 1
Un_FSG__:00401577 push eax
Un_FSG__:00401578 mov eax, [ebp+b]
Un_FSG__:0040157E push eax
Un_FSG__:0040157F mov eax, [ebp+a]
Un_FSG__:00401585 push eax
Un_FSG__:00401586 call _ecurve_init
Un_FSG__:0040158B mov eax, [ebp+pt1_x]
Un_FSG__:00401591 add esp, 20h
Un_FSG__:00401594 push edi ; pt1
Un_FSG__:00401595 push 0
Un_FSG__:00401597 push eax
Un_FSG__:00401598 mov eax, [ebp+pt1_x]
Un_FSG__:0040159E push eax
Un_FSG__:0040159F call _epoint_set
Un_FSG__:004015A4 mov ecx, [ebp+pt2_x]
Un_FSG__:004015AA mov eax, [ebp+pt2]
Un_FSG__:004015B0 mov ebx, [ebp+pt2_x]
Un_FSG__:004015B6 push eax
Un_FSG__:004015B7 push 1
Un_FSG__:004015B9 push ebx
Un_FSG__:004015BA push ecx
Un_FSG__:004015BB call _epoint_set
Un_FSG__:004015C0 mov esi, [ebp+big_sn1]
Un_FSG__:004015C6 add esp, 18h
Un_FSG__:004015C9 movsx ebx, ds:Serial_sign
Un_FSG__:004015D0 push offset sn1
Un_FSG__:004015D5 sub ebx, 30h
Un_FSG__:004015D8 push esi
Un_FSG__:004015D9 lea esi, [ebp+var_1A8]
Un_FSG__:004015DF call _cinstr
Un_FSG__:004015E4 pop eax
Un_FSG__:004015E5 pop edx
Un_FSG__:004015E6 mov eax, [ebp+big_sn2]
Un_FSG__:004015EC push offset sn2
Un_FSG__:004015F1 push eax
Un_FSG__:004015F2 call _cinstr
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