###### tags : `CTF PWN基礎題`
# 題目:sysmagic
#### 練習目的:gdb調用與測試

* 題目: https://drive.google.com/file/d/1Oc8yU0aHa5WqmLv5lhkN7g3njYWYszd3/view?usp=sharing
* 題目: https://drive.google.com/file/d/1TwthQXDHEFX-rEjKeBKy9OJPQvshb4b2/view?usp=sharing

- step1. ==查看原代碼==

    #include <stdio.h>
    #include <unistd.h>



    void get_flag(){
        int fd ;
        int password;
        int magic ;
        char key[] = "Do_you_know_why_my_teammate_Orange_is_so_angry???";
        char cipher[] = {7, 59, 25, 2, 11, 16, 61, 30, 9, 8, 18, 45, 40, 89, 10, 0, 30, 22, 0, 4, 85, 22, 8, 31, 7, 1, 9, 0, 126, 28, 62, 10, 30, 11, 107, 4, 66, 60, 44, 91, 49, 85, 2, 30, 33, 16, 76, 30, 66};
        fd = open("/dev/urandom",0);
        read(fd,&password,4);
        printf("Give me maigc :");
        scanf("%d",&magic);
        if(password == magic){
            for(int i = 0 ; i < sizeof(cipher) ; i++){
                printf("%c",cipher[i]^key[i]);
            }
        }
    }


    int main(){
        setvbuf(stdout,0,2,0);
        get_flag();
        return 0 ;
        }

- 看懂程式邏輯

- step2. ==開始玩gdb==


- step3. ==進入gdb==
- 設置斷點,查看斷點
- 指令:b XXXXXXX
- step4. ==用gdb修改你想改的值==

- 指令:set XXXXXXX

- step4. ==應該就有flag了吧==

- flag{XXXXXXX}