pwnable.kr-random-Writeup

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pwnable.kr-random-Writeup

• 与前几题套路相同，ssh远程登录，ls -l查看文件及权限，cat获得C代码如下：

 #include <stdio.h>

 int main(){
     unsigned int random;
     random = rand();    // random value!

     unsigned int key=;
     scanf("%d", &key);

     if( (key ^ random) == 0xdeadbeef ){
         printf("Good!\n");
         system("/bin/cat flag");
         return ;
     }

     printf("Wrong, maybe you should try 2^32 cases.\n");
     return ;
 }

• 查看random（）函数时有这样的描述：

• 即该函数每次产生的随机值均为定值，自己写一个类似的程序可以得到此时产生的随机值为1804289383

• 根据代码流程，1804289383 ^ 0xdeadbeef即可得到要输入的key值为3039230856，则可得到flag为 Mommy, I thought libc random is unpredictable...

2017-2-7 22:01;32