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SSH Honeypot

This unfortunately named program listens for incoming ssh connections and logs the IP address, username, and password used by the client. This is a low-interaction honeypot that does not allow malware or attackers to login.

This was originally written to gather rudimentary intelligence on brute force attacks and not meant for production usage.

Nowadays, I mostly use this at attack/defend CTFs paired with sshunt: https://github.com/droberson/sshunt

I set up sshunt to forward tools such as Hydra, Metasploit, and Ncrack to ssh-honeypot and allow OpenSSH clients to connect to ssh normally.

Quickstart

Linux

Make sure headers/development packages are installed for:

  • libssh
  • openssl
  • libjson-c
  • libpcap
apt install libssh-dev libjson-c-dev libpcap-dev libssl-dev

Build and Run

make
ssh-keygen -t rsa -f ./ssh-honeypot.rsa
bin/ssh-honeypot -r ./ssh-honeypot.rsa

OSX (experimental/unsupported)

WARNING: I haven't tested JSON logging, HASSH, or anything really on OSX. MacOS is officially unsupported as I do not own any Macs to test this software with.

Make sure that xcode is up to date.

Install libssh and json-c

brew install libssh json-c

Specify MakefileOSX with make:

make -f MakefileOSX

Docker (experimental)

Please take a look at our Docker documentation.

HASSH

As of version 0.2.0, ssh-honeypot attempts to calculate the HASSH of the client software initiating sessions with ssh-honeypot. In short, you can tell if the client is using OpenSSH, PuTTY, SecureCRT, ...

For more information about HASSH, refer to these links:

Syslog facilities

As of version 0.0.5, this supports logging to syslog. This feature is toggled with the -s flag. It is up to you to configure your syslog facilities appropriately. This logs to LOG_AUTHPRIV which is typically /var/log/auth.log. You may want to modify this to use one of the LOG_LOCAL facilities if you are worried about password leakage.

Dropping Privileges

As of version 0.0.8, you can drop root privileges of this program after binding to a privileged port. You can now run this as nobody on port 22 for example instead of root, but have to initially start it as root:

sudo bin/ssh-honeypot -p 22 -u nobody

Beware that this chowns the logfile to the user specified as well.

Changing the Banner

ssh-honeypot allows you to change the server's banner to blend in with other hosts on your network or mimic a specific device.

List available banners

bin/ssh-honeypot -b

Set banner string

bin/ssh-honeypot -b "my banner string"

Set banner by index

bin/ssh-honeypot -i <banner index>

JSON Logging

The -j CLI flag specifies the path to log results in JSON format. This feature can make log analytics much easier because many languages have robust JSON support.

JSON logs can be sent to a remote host. The -J and -P CLI flags set the host and port to send logs in JSON to, respectively. At this time, logs are transmitted using UDP and not encrypted.

This feature can be useful when running multiple ssh-honeypot instances. Listeners can be created for Splunk and ElasticSearch to ingest these logs and make them searchable.

Systemd Integration

On Linux you can install ssh-honeypot as a Systemd service so that it automatically runs at system startup:

make install
systemctl enable --now ssh-honeypot

Before installing, check ssh-honeypot.service and modify it to run with the options you want.