pwnable.kr-flag-Writeup

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pwnable.kr-flag-Writeup

• 根据题目提示：This is reversing task. all you need is binary，可知此题实际上应归为reverse；
• DIE查壳，发现为upx加壳，直接使用upx工具脱壳
• Linux下运行该文件，发现关键字符串
• IDA中shift+F12找到关键字符串，并双击关键字符串跳转到对应的函数，得到伪代码如下：

 int __cdecl main(int argc, const char **argv, const char **envp)
 {
   __int64 v3; // rax@1

   puts("I will malloc() and strcpy the flag there. take it.", argv, envp);
   LODWORD(v3) = malloc(100LL);
   sub_400320(v3, flag);
   return ;
 }

• 由提示I will malloc() and strcpy the flag there. take it.以及代码的流程，直接查看flag，得到字符串：UPX...? sounds like a delivery service :),提交检验正确，则flag即为 UPX...? sounds like a delivery service :) 事实上，shift+F12查找关键字符串时已经出现了flag 2017-2-7 20:54;45