1.查壳

发现有UPX壳

脱壳

运行

回车后程序直接退出

2.IDA静态分析

int __cdecl main(int argc, const char **argv, const char **envp)
{
  char Str2[14]; // [esp+12h] [ebp-3Ah] BYREF
  char Str1[44]; // [esp+20h] [ebp-2Ch] BYREF

  __main();
  strcpy(Str2, "HappyNewYear!");
  memset(Str1, 0, 32);
  printf("please input the true flag:");
  scanf("%s", Str1);
  if ( !strncmp(Str1, Str2, strlen(Str2)) )
    return puts("this is true flag!");
  else
    return puts("wrong!");
}

程序逻辑很简单，
flag为:flag{HappyNewYear!}