娃娃的CCG crackme3简要分析(P-CODE型)

目标:娃娃的CCG CRACKME3

工具:WKTVBDebugger v1.3,exdec(以上工具在风飘学兄的站点有下载)

首先我得多谢master兄引我上路,要不到现在我还不知道怎么弄P-CODE的东东,这两天从风飘雪兄的网站下了几个CRACKME,练习了一下,效果还不错,这个可是我自己连猜带蒙搞定的哦!!!哦,对了还要多谢好友upfeed每次耐心地听我罗嗦及对我不吝其口舌的指点!!!还有一位很可爱的老朋友,尽管此君老大年纪了,居然还是和我一样单身,哎,同病相怜啊,谢谢你老人家给予我信心!!!

顺便说一句,我从开始学着用exdec和wktvbdebugger到搞定这个东东的算法总共不到5小时,哇,这样一看,pcode的入门也不是很难嘛,所以会pcode的高手一定很多,帮忙看看我的分析有啥不对的啦!多谢!

代码如下,用exdec反编译的,哦,如果静态分析有困难,可以用WKTVBDebugger,由于是在输入的同时进行验证,所以我们在EDIT上下断点,方法:用WKTVBDebugger打开crackme,点Form Manager,拉下拉框选择main,然后选择TEXTBOX,下拉框选择TEXT1,点BPX钮,OK,现在按F5执行程序,在输入框中输入任何东东,立刻断下来了:)于是到了这里....

40EAAC: 04 FLdRfVar local_00E0 ==>push address这玩艺过会存放字符串的地址,

40EAAF: 21 FLdPrThis ==>这里我怀疑是取程序本身的句柄,不确定,请高手指点

40EAB0: 0f VCallAd (object 2 ) ==>之所以有上面的怀疑是因为这里wktvbdbg注释为

==>main.text1,所以猜是调用某程序自身的函数

40EAB3: 19 FStAdFunc local_00DC

40EAB6: 08 FLdPr local_00DC

40EAB9: 0d VCallHresult id ==>get_ipropTEXTEDIT 得到输入字符串

40EABE: 3e FLdZeroAd local_00E0 ==>字符串地址指针

40EAC1: 46 CVarStr local_00F0 ==>复制指针到local_00F0

40EAC4: 04 FLdRfVar local_0100 ==>push函数参数,WKTVBdbg走到这里可以看 ==>locao_0100+8所指代的内存,那是你输入的东东

40EAC7: 0a ImpAdCallFPR4:  ==>rtvTrimVar相当于what?VB高手告诉我这函数干嘛用的 ==>好吗?

40EACC: 04 FLdRfVar local_0100 ==>push字符串

40EACF: Lead0/eb FnLenVar ==>得到字符串长度

40EAD3: Lead1/f6 FStVar ==>将长度存到某处,哪里我没弄明白:(

40EAD7: 1a FFree1Ad local_00DC

40EADA: 36 FFreeVar ==>free...

40EAE1: f4 LitI2_Byte: 0x1 1 (.) ==>push 1 as byte???

40EAE3: 04 FLdRfVar local_00D6

40EAE6: 04 FLdRfVar local_00D4

40EAE9: 55 CI2Var ==>这里应该是相当于计数器i了,当然是以刚才取的长度为...

40EAEA: Lead3/63 ForI2: (when done) 40EB5D==>靠,总算见着个确定的函数,for语句,都见过吧:)

40EAF0: 21 FLdPrThis ==>看看,又是一个,我刚才说过我的猜测了

40EAF1: 0f VCallAd (object 2 ) ==>某函数???

40EAF4: 19 FStAdFunc local_00DC

40EAF7: 28 LitVarI2: ( local_0100 ) 0x1 (1)==>把常数1赋给local_0100,然后将此变量入栈

40EAFC: 6b FLdI2 local_00D6 ==>这里是计数器i

40EAFF: e7 CI4UI1 ==>似乎起符号扩展的作用,大伙看看

40EB00: 3e FLdZeroAd local_00DC

40EB03: Lead2/6f CVarAd

40EB07: 04 FLdRfVar local_0110

40EB0A: 0a ImpAdCallFPR4:  ==>这里是rtcMidChar,这十几行就是Mid$(str,i,1)

40EB0F: 04 FLdRfVar local_0110

40EB12: Lead1/f6 FStVar

40EB16: 1a FFree1Ad local_00DC

40EB19: 36 FFreeVar

40EB20: 04 FLdRfVar local_0094

40EB23: Lead2/fe CStrVarVal local_00E0 ==>取得的字符地址入栈

40EB27: 0b ImpAdCallI2 ==>call rtcAnsiValueBstr,就是ASC$(char)

40EB2C: 44 CVarI2 local_0124 ==>字符的ASCII值

40EB2F: Lead1/f6 FStVar

40EB33: 2f FFree1Str local_00E0

40EB36: 04 FLdRfVar local_00B4 ==>这个应是返回值了

40EB39: 6b FLdI2 local_00D6 ==>当当当....当!计数器i出现,干什么用呢?

40EB3C: 44 CVarI2 local_0124 ==>哇,取得的字符也出现了

40EB3F: Lead0/94 AddVar local_00F0 ==>原来是加起来用啊

40EB43: Lead1/f6 FStVar

40EB47: 04 FLdRfVar local_00A4 ==>这个东东是sum

40EB4A: 04 FLdRfVar local_00B4 ==>这个东东是刚才的结果

40EB4D: Lead0/94 AddVar local_00F0 ==>两个东东加一起

40EB51: Lead1/f6 FStVar ==>放到local_00A4里面去.哦哦...

40EB55: 04 FLdRfVar local_00D6 ==>计数器i再次登场

40EB58: 64 NextI2: (continue) 40EAF0==>是否继续???

40EB5D: 04 FLdRfVar local_00A4 ==>刚才我说过的sum

40EB60: 28 LitVarI2: ( local_0124 ) 0x6e4 (1764)==>一个常数0x6e4

40EB65: 5d HardType

40EB66: Lead0/33 EqVarBool ==>两者是否相等?

40EB68: 1c BranchF: 40EB94 ==>不等就错误了:)

40EB6B: 1b LitStr: "恭喜你..."

40EB6E: 21 FLdPrThis

40EB6F: 0f VCallAd (object 2 )

40EB72: 19 FStAdFunc local_00DC

40EB75: 08 FLdPr local_00DC

40EB78: 0d VCallHresult 禚d ==>put _ipropTEXTEDIT写下几句肉麻的话^_*

40EB7D: 1a FFree1Ad local_00DC

40EB80: f4 LitI2_Byte: 0x0 0 (.)

40EB82: 21 FLdPrThis

40EB83: 0f VCallAd (object 1 )

40EB86: 19 FStAdFunc local_00DC

40EB89: 08 FLdPr local_00DC

40EB8C: 0d VCallHresult 禚d

总结:

算法如下:int sum=0;int char,len;

gets(str);len=strlen(str);

for (int i=0;i