查壳 发现upx壳
尝试脱壳工具脱壳失败,菜鸡不会手脱啊啊啊,只能一步一步od跟了
发现00301050 是main函数
获取输入后调用00301000加密输入的字符,0301000核心,将每一个输入的字符串ascii码加上302ff8数组 取内容 即为输入对应的加密字符
将加密后的字符与DDCTF{reverseME}做对比相等则输入正确
解密代码
// ConsoleApplication2.cpp : 此文件包含 "main" 函数。程序执行将在此处开始并结束。
//
#include <iostream>
using namespace std;
int main()
{
char AnsiChar [140] = {
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x1B, 0x0E, 0x11, 0x66, 0xE4, 0xF1, 0xEE, 0x99,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFE, 0xFF, 0xFF, 0xFF, 0x01, 0x00, 0x00, 0x00,
0x7E, 0x7D, 0x7C, 0x7B, 0x7A, 0x79, 0x78, 0x77, 0x76, 0x75, 0x74, 0x73, 0x72, 0x71, 0x70, 0x6F,
0x6E, 0x6D, 0x6C, 0x6B, 0x6A, 0x69, 0x68, 0x67, 0x66, 0x65, 0x64, 0x63, 0x62, 0x61, 0x60, 0x5F,
0x5E, 0x5D, 0x5C, 0x5B, 0x5A, 0x59, 0x58, 0x57, 0x56, 0x55, 0x54, 0x53, 0x52, 0x51, 0x50, 0x4F,
0x4E, 0x4D, 0x4C, 0x4B, 0x4A, 0x49, 0x48, 0x47, 0x46, 0x45, 0x44, 0x43, 0x42, 0x41, 0x40, 0x3F,
0x3E, 0x3D, 0x3C, 0x3B, 0x3A, 0x39, 0x38, 0x37, 0x36, 0x35, 0x34, 0x33, 0x32, 0x31, 0x30, 0x2F,
0x2E, 0x2D, 0x2C, 0x2B, 0x2A, 0x29, 0x28, 0x27, 0x26, 0x25, 0x24, 0x23, 0x22, 0x21, 0x20, 0x00,
0x01, 0x00, 0x00, 0x00, 0x28, 0x1D, 0x56, 0x00, 0x78, 0x18, 0x56, 0x00
};
char cByte[] = { "DDCTF{reverseME}" };
char cFlag[0x100] = { 0 };
int j = 0;
for (int i = 0; i < 140; i++)
{
if (AnsiChar[i] == cByte[j])
{
cFlag[j] = i;
i = 0;
j++;
}
}
}
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