A fake SSH server that lets everyone in and logs their activity
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Kristóf Jakab
Latest commit b74f93f Nov 16, 2016

README.md

sshesame

A fake SSH server that lets everyone in and logs their activity

Warning

This software, just like any other, might contain bugs. Given the popular nature of SSH, you probably shouldn't run it unsupervised as root on a production server on port 22. Use common sense.

Motivation

I was just curious what all these guys were up to:

sshd[8128]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=<client>  user=root
sshd[8128]: Failed password for root from <client> port 37510 ssh2
sshd[8128]: Received disconnect from <client> port 37510:11:  [preauth]
sshd[8128]: Disconnected from <client> port 37510 [preauth]
sshd[8141]: Received disconnect from <client> port 59353:11:  [preauth]
sshd[8141]: Disconnected from <client> port 59353 [preauth]
sshd[8151]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=<client>  user=root
sshd[8151]: Failed password for root from <client> port 63785 ssh2
sshd[8159]: Received disconnect from <client> port 24889:11:  [preauth]
sshd[8159]: Disconnected from <client> port 24889 [preauth]

Details

sshesame accepts and logs

  • every password authentication request,
  • every SSH channel open request and
  • every SSH request

without actually executing anything on the host.

For more details, read the relevant RFC.

Installing

From source

  • Install go (version 1.4 or newer required)
  • go get -u github.com/jaksi/sshesame

Snap

snap install sshesame

Package created and maintained by chadmiller.

You can find the package here.

Usage

$ sshesame -h
Usage of sshesame:
  -host_key string
    	a file containing a private key to use
  -json_logging
    	enable logging in JSON
  -listen_address string
    	the local address to listen on (default "localhost")
  -port uint
    	the port number to listen on (default 2022)
  -server_version string
    	The version identification of the server (RFC 4253 section 4.2 requires that this string start with "SSH-2.0-") (default "SSH-2.0-sshesame")

Consider creating a private key to use with sshesame, for example using ssh-keygen.

Example output

Connection: client=<client>:45782
Login: client=<client>:45782, user="root", password="cisco"
Established SSH connection: client=<client>:45782
New channel: clinet=<client>:45782, type=direct-tcpip, payload={DestinationAddress:<something> DestinationPort:110 SourceAddress:192.168.0.1 SourcePort:0}
Failed to read from channel: EOF
New channel: clinet=<client>:45782, type=direct-tcpip, payload={DestinationAddress:<something> DestinationPort:143 SourceAddress:192.168.0.1 SourcePort:0}
Failed to read from channel: EOF
New channel: clinet=<client>:45782, type=direct-tcpip, payload={DestinationAddress:<something> DestinationPort:587 SourceAddress:192.168.0.1 SourcePort:0}
Failed to read from channel: EOF
New channel: clinet=<client>:45782, type=direct-tcpip, payload={DestinationAddress:<something> DestinationPort:587 SourceAddress:192.168.0.1 SourcePort:0}
Failed to read from channel: EOF
New channel: clinet=<client>:45782, type=session, payload=[]
Request: client=<client>:45782, channel=session, type=exec, payload={Command:/sbin/ifconfig}
Failed to read from terminal: EOF
New channel: clinet=<client>:45782, type=session, payload=[]
Request: client=<client>:45782, channel=session, type=exec, payload={Command:cat /proc/meminfo}
Failed to read from terminal: EOF
New channel: clinet=<client>:45782, type=session, payload=[]
Request: client=<client>:45782, channel=session, type=exec, payload={Command:2>/dev/null sh -c 'cat /lib/libdl.so* || cat /lib/librt.so* || cat /bin/cat || cat /sbin/ifconfig'}
Failed to read from terminal: EOF
New channel: clinet=<client>:45782, type=session, payload=[]
Request: client=<client>:45782, channel=session, type=exec, payload={Command:cat /proc/version}
Failed to read from terminal: EOF
New channel: clinet=<client>:45782, type=session, payload=[]
Request: client=<client>:45782, channel=session, type=exec, payload={Command:uptime}
Failed to read from terminal: EOF
Disconnect: client=<client>:45782

So what happened here?

  • A client logged in with the user "root" and the password "cisco"
  • Using TCP/IP forwarding over SSH, they tried to connect to a few remote mail servers over POP3 (port 110), IMAP (port 143) and Submission (port 587)
  • They tried to execute a few commands to get some information about the host

Again, if you're interested in the technical details of SSH, read the RFC.

Known issues

  • No exit-status request is sent in response to exec requests
  • A terminal is created on session channels even if no shell request is received