新160个crackme - 059-Dope2112.1

news2024/9/20 10:02:01

运行分析

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输入Name和Serial，点击Registrieren按钮，显示疑似错误提示
百度翻译查看一下，发现是德语

PE分析

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Delphi程序，32位，无壳

静态分析&动态调试

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ida字符串发现正确提示，双击跟进

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来到关键函数，进行动态调试，发现要想跳转至成功提示，需要使136行cmp(v21,Names)相等，分析计算过程如下：
1、提取Name前6位进行计算，得到低位v5
2、将Name长度乘19070的结果为v20
3、v5十六进制转十进制，得到v17
3、拼接字符串，v21 = v20 + dword_421DD8 + v17
4、dword_421DD8 的值为’-’

算法分析

Name = 'concealbear'
Serial = ''
dword_421DD8 = '-'

v5 = 93
for i in range(0,5):
    if Name[i] == 'a':
        v7 = 24
    elif Name[i] == 'b':
        v7 = 37
    elif Name[i] == 'c':
        v7 = 66
    elif Name[i] == 'd':
        v7 = 12
    elif Name[i] == 'e':
        v7 = 13
    elif Name[i] == 'f':
        v7 = 6
    elif Name[i] == 'g':
        v7 = 54
    elif Name[i] == 'h':
        v7 = 43
    elif Name[i] == 'i':
        v7 = 23
    elif Name[i] == 'j':
        v7 = 47
    elif Name[i] == 'k':
        v7 = 19
    elif Name[i] == 'l':
        v7 = -126
    elif Name[i] == 'm':
        v7 = -101
    elif Name[i] == 'n':
        v7 = -110
    elif Name[i] == 'o':
        v7 = 3
    elif Name[i] == 'p':
        v7 = 99
    elif Name[i] == 'q':
        v7 = 33
    elif Name[i] == 'r':
        v7 = 66
    elif Name[i] == 's':
        v7 = 92
    elif Name[i] == 't':
        v7 = 41
    elif Name[i] == 'u':
        v7 = -57
    elif Name[i] == 'v':
        v7 = 102
    elif Name[i] == 'w':
        v7 = 88
    elif Name[i] == 'x':
        v7 = 10
    elif Name[i] == 'y':
        v7 = 40
    elif Name[i] == 'z':
        v7 = 80
    else:
        v7 = 93
    v5 = (v5 + v7) & 0xff

v20 = len(Name) * 19070
v17 = v5

Serial = str(v17) + dword_421DD8 + str(v20)

print(Name + '的Serial为：\n' + Serial)