Posted on 2009-09-20 23:53
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Crack
在所有的 GetWindowText 設(shè)置斷點(diǎn)
Ctrl + F2 重新開始
00401323? |.? E8 4C010000?? call??? <jmp.&USER32.GetWindowTextA>???? ; \GetWindowTextA
00401328? |.? E8 A5000000?? call??? 004013D2???????????????????????????????????????????? <--- 執(zhí)行完這個(gè)之后，結(jié)果就放到 esi,
0040132D? |.? 3BC6????????? cmp???? eax, esi???????????????????????????????????????????????????? <--- 然后跟 eax 進(jìn)行比較
0040132F? |.? 75 42???????? jnz???? short 00401373
00401331? |.? EB 2C???????? jmp???? short 0040135F
相關(guān)的匯編指令：
CMP
功能: 比較OP1與OP2的值
語(yǔ)法: CMP r/m,r/m/data
標(biāo)志位: C,P,A,Z,O
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Z == 0 ，則認(rèn)為這兩個(gè)數(shù)相等
JNZ
JNZ 就是zf標(biāo)志不為1轉(zhuǎn)移
匯編語(yǔ)言標(biāo)志寄存器標(biāo)志位說(shuō)明
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標(biāo)志
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名稱
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值為1的標(biāo)志
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值為0的標(biāo)志
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說(shuō)明
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OF
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Overflow Flag
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OV(OVERFLOW)
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NV(NOT OVERFLOW)
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ALU是否溢出標(biāo)志
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SF
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Sign Flag
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NG(NEGTIVE)
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PL(PLUS)
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是否結(jié)果為負(fù)標(biāo)志
(該標(biāo)志的值總是ALU運(yùn)算后最高位的結(jié)果保持一致)
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ZF
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Zero Flag
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ZR(ZERO)
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NZ(NOT ZERO)
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是否結(jié)果為0標(biāo)志
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PF
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Parity Flag
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PE(PARITY EVEN)
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PO(PARITY ODD)
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ALU結(jié)果中1的個(gè)數(shù)的奇偶位
(確切地說(shuō)是ALU的低八位中1的個(gè)數(shù))
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CF
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Carry Flag
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CY(CARRIED)
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NC(NOT CARRIED)
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是否借位或進(jìn)位標(biāo)志
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DF
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Direction Flag
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DN(DOWN)
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UP(UP)
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方向標(biāo)志，若值為1則數(shù)據(jù)串指令從高地址向低地址方向步進(jìn)
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TF
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Trap Flag
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值為1的時(shí)候每執(zhí)行一次指令便產(chǎn)生一條內(nèi)中斷指令
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IF
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Interupt Flag
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值為1的時(shí)候CPU可響應(yīng)可屏蔽中斷指令
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AF
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Auxiliary Carry Flag
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加、減算術(shù)指令執(zhí)行后，最低4位D 3
~
D 0位有進(jìn)位或借位，AF=1；無(wú)進(jìn)位或借位，AF=0。該標(biāo)志用于系統(tǒng)進(jìn)行BCD碼的算術(shù)運(yùn)算結(jié)果的調(diào)整
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00401323? |.? E8 4C010000?? call??? <jmp.&USER32.GetWindowTextA>???? ; \GetWindowTextA
00401328? |.? E8 A5000000?? call??? 004013D2???????????????????????????????????????????? <--- 執(zhí)行完這個(gè)之后，結(jié)果就放到 esi,
0040132D? |.? 3BC6????????? cmp???? eax, esi???????????????????????????????????????????????????? <--- 然后跟 eax 進(jìn)行比較
0040132F? |.? 75 42???????? jnz???? short 00401373??????????????????????????????????????????? <--- 肯定有地方修改了A這個(gè)標(biāo)志位
00401331? |.? EB 2C???????? jmp???? short 0040135F
Ctrl + F2 再來(lái)一次，00401328? |.? E8 A5000000?? call??? 004013D2?????F7跟進(jìn)去
004013D2? /$? 56??????????? push??? esi?????????????????????????????????????????? <--- 因?yàn)檫@個(gè) function 要修改到 esi ，所以先保存 esi 的值，最后一定會(huì) pop esi
004013D3? |.? 33C0????????? xor???? eax, eax????????????????????????????????????????? 清 eax 的值
004013D5? |.? 8D35 C4334000 lea???? esi, dword ptr [4033C4]????????? LEA 裝入有效地址.? 例: LEA DX,string ;把偏移地址存到DX.
004013DB? |.? 33C9????????? xor???? ecx, ecx????????????????????????????????????????? 清 ecx
004013DD? |.? 33D2????????? xor???? edx, edx???????????????????????????????????????? 清 edx
004013DF? |.? 8A06????????? mov???? al, byte ptr [esi]????????????????????????????
004013E1? |.? 46??????????? inc???? esi
004013E2? |.? 3C 2D???????? cmp???? al, 2D
004013E4? |.? 75 08???????? jnz???? short 004013EE
004013E6? |.? BA FFFFFFFF?? mov???? edx, -1
004013EB? |.? 8A06????????? mov???? al, byte ptr [esi]
004013ED? |.? 46??????????? inc???? esi
004013EE? |>? EB 0B???????? jmp???? short 004013FB
004013F0? |>? 2C 30???????? /sub???? al, 30
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