1.查壳

PE32 无壳

2.IDA静态分析

(1)main

// attributes: thunk
int __cdecl main(int argc, const char **argv, const char **envp)
{
  return main_0(argc, argv, envp);
}

main_0

int __cdecl main_0(int argc, const char **argv, const char **envp)
{
  int v3; // eax
  const char *v4; // eax
  size_t v5; // eax
  char v7; // [esp+0h] [ebp-188h]
  char v8; // [esp+0h] [ebp-188h]
  signed int j; // [esp+DCh] [ebp-ACh]
  int i; // [esp+E8h] [ebp-A0h]
  signed int v11; // [esp+E8h] [ebp-A0h]
  char Destination[108]; // [esp+F4h] [ebp-94h] BYREF
  char Str[28]; // [esp+160h] [ebp-28h] BYREF
  char v14[8]; // [esp+17Ch] [ebp-Ch] BYREF

  for ( i = 0; i < 100; ++i )
  {
    if ( (unsigned int)i >= 0x64 )
      j____report_rangecheckfailure();
    Destination[i] = 0;
  }
  sub_41132F("please enter the flag:", v7);
  sub_411375("%20s", (char)Str);
  v3 = j_strlen(Str);
  v4 = (const char *)sub_4110BE((int)Str, v3, (int)v14);
  strncpy(Destination, v4, 0x28u);
  v11 = j_strlen(Destination);
  for ( j = 0; j < v11; ++j )
    Destination[j] += j;
  v5 = j_strlen(Destination);
  if ( !strncmp(Destination, Str2, v5) )
    sub_41132F("rigth flag!\n", v8);
  else
    sub_41132F("wrong flag!\n", v8);
  return 0;
}

程序逻辑分析:
（1）用户输入为Str，在第24行执行sub_4110BE对其进行处理。
（2）将用户输入处理后的返回值v4复制给数组Destination。
（3）对数组Destination进行元素和下标的循环加和。

(2)sub_4110BE