Bandit Level 21 → Level 22

A program is running automatically at regular intervals from cron, the time-based job scheduler. Look in /etc/cron.d/ for the configuration and see what command is being executed.

解密

bandit21@bandit:~$ ls -l /etc/cron.d/
total 12
-rw-r--r-- 1 root root 120 Oct 16  2018 cronjob_bandit22
-rw-r--r-- 1 root root 122 Oct 16  2018 cronjob_bandit23
-rw-r--r-- 1 root root 120 Oct 16  2018 cronjob_bandit24
bandit21@bandit:~$ crontab -l
crontabs/bandit21/: fopen: Permission denied
bandit21@bandit:~$ cat /etc/cron.d/cronjob_bandit22
@reboot bandit22 /usr/bin/cronjob_bandit22.sh &> /dev/null
* * * * * bandit22 /usr/bin/cronjob_bandit22.sh &> /dev/null
bandit21@bandit:~$ cat /usr/bin/cronjob_bandit22.sh
#!/bin/bash
chmod 644 /tmp/t7O6lds9S0RqQh9aMcz6ShpAoZKF7fgv
cat /etc/bandit_pass/bandit22 > /tmp/t7O6lds9S0RqQh9aMcz6ShpAoZKF7fgv
bandit21@bandit:~$ cat /tmp/t7O6lds9S0RqQh9aMcz6ShpAoZKF7fgv
Yk7owGAcWjwMVRwrTesJEwB7WVOiILLI

知识点

1. cron是linux的定时任工具；
2. crontab查看运行定时任务（在这里不能使用）；
3. 根据提示，查看/etc/cron.d/下的定时任务；
4. 查看相关脚本，发现是把密码写到/tmp下的一个文件，查看得到密码；