AlterX Subdomain Wordlist Generator Cheat Sheet

Overview

AlterX is a fast and customizable subdomain wordlist generator developed by Project Discovery. It uses patterns and domain-specific language (DSL) to generate permutations and alterations of subdomains, making it a powerful tool for active subdomain enumeration. AlterX fits into the active subdomain enumeration pipeline, complementing passive subdomain discovery tools like Subfinder.

What sets AlterX apart from other wordlist generators is its pattern-based approach and its ability to generate targeted, context-aware wordlists. Instead of using generic wordlists, AlterX can create permutations based on known subdomains, allowing for more effective discovery of related subdomains. This approach significantly increases the chances of finding valid subdomains during security assessments and bug bounty hunting.

AlterX is designed to be used in combination with tools like ShuffleDNS or other DNS brute-forcing tools to discover new subdomains that might not be found through passive enumeration methods. Its customizable patterns and efficient generation algorithm make it an essential tool for comprehensive subdomain enumeration.

Installation

Using Go

# Install using Go (requires Go 1.20 or later)
go install -v github.com/projectdiscovery/alterx/cmd/alterx@latest

# Verify installation
alterx -version

Using Docker

# Pull the latest Docker image
docker pull projectdiscovery/alterx:latest

# Run AlterX using Docker
docker run -it projectdiscovery/alterx:latest -h

Using Homebrew (macOS)

# Install using Homebrew
brew install alterx

# Verify installation
alterx -version

Using PDTM (Project Discovery Tools Manager)

# Install PDTM first if not already installed
go install -v github.com/projectdiscovery/pdtm/cmd/pdtm@latest

# Install AlterX using PDTM
pdtm -i alterx

# Verify installation
alterx -version

On Kali Linux

# Install using apt
sudo apt install alterx

# Verify installation
alterx -version

Basic Usage

Generating Wordlists

# Generate wordlist using default patterns
alterx -l subdomains.txt

# Generate wordlist with specific pattern
alterx -l subdomains.txt -p "{{word}}-dev"

# Generate wordlist from a single domain
alterx -d example.com -p "{{word}}-{{number}}"

# Generate wordlist from multiple domains
alterx -d example.com,hackerone.com -p "{{word}}-{{number}}"

Output Options

# Save results to a file
alterx -l subdomains.txt -o wordlist.txt

# Output in JSON format
alterx -l subdomains.txt -json -o wordlist.json

# Silent mode (only wordlist entries)
alterx -l subdomains.txt -silent

Pattern Usage

Basic Patterns

# Use word pattern (extracts words from input)
alterx -l subdomains.txt -p "{{word}}"

# Use number pattern (extracts numbers from input)
alterx -l subdomains.txt -p "{{number}}"

# Use character pattern (extracts characters from input)
alterx -l subdomains.txt -p "{{char}}"

# Combine multiple patterns
alterx -l subdomains.txt -p "{{word}}-{{number}}"

Advanced Patterns

# Use prefix pattern
alterx -l subdomains.txt -p "dev-{{word}}"

# Use suffix pattern
alterx -l subdomains.txt -p "{{word}}-prod"

# Use multiple patterns
alterx -l subdomains.txt -p "{{word}}-dev,{{word}}-prod,{{word}}-stage"

# Use patterns from a file
alterx -l subdomains.txt -pf patterns.txt

Pattern Modifiers

# Use uppercase modifier
alterx -l subdomains.txt -p "{{word:uppercase}}"

# Use lowercase modifier
alterx -l subdomains.txt -p "{{word:lowercase}}"

# Use capitalize modifier
alterx -l subdomains.txt -p "{{word:capitalize}}"

# Use multiple modifiers
alterx -l subdomains.txt -p "{{word:lowercase:capitalize}}"

Advanced Usage

Word Extraction

# Extract words from input
alterx -l subdomains.txt -p "{{word}}" -extract-words

# Set minimum word length
alterx -l subdomains.txt -p "{{word}}" -min-word-length 3

# Set maximum word length
alterx -l subdomains.txt -p "{{word}}" -max-word-length 10

Number Extraction

# Extract numbers from input
alterx -l subdomains.txt -p "{{number}}" -extract-numbers

# Set minimum number length
alterx -l subdomains.txt -p "{{number}}" -min-number-length 1

# Set maximum number length
alterx -l subdomains.txt -p "{{number}}" -max-number-length 5

Character Extraction

# Extract characters from input
alterx -l subdomains.txt -p "{{char}}" -extract-chars

# Set minimum character length
alterx -l subdomains.txt -p "{{char}}" -min-char-length 1

# Set maximum character length
alterx -l subdomains.txt -p "{{char}}" -max-char-length 3

Pattern Examples

Common Subdomain Patterns

# Development environments
alterx -l subdomains.txt -p "{{word}}-dev,dev-{{word}},{{word}}.dev"

# Staging environments
alterx -l subdomains.txt -p "{{word}}-stage,stage-{{word}},{{word}}.stage"

# Production environments
alterx -l subdomains.txt -p "{{word}}-prod,prod-{{word}},{{word}}.prod"

# API endpoints
alterx -l subdomains.txt -p "api-{{word}},{{word}}-api,api.{{word}}"

# Admin panels
alterx -l subdomains.txt -p "admin-{{word}},{{word}}-admin,admin.{{word}}"

Numeric Patterns

# Append numbers
alterx -l subdomains.txt -p "{{word}}{{number}}"

# Prepend numbers
alterx -l subdomains.txt -p "{{number}}{{word}}"

# Separate with hyphen
alterx -l subdomains.txt -p "{{word}}-{{number}}"

# Separate with dot
alterx -l subdomains.txt -p "{{word}}.{{number}}"

Regional Patterns

# Geographic regions
alterx -l subdomains.txt -p "{{word}}-us,{{word}}-eu,{{word}}-asia"

# Countries
alterx -l subdomains.txt -p "{{word}}-uk,{{word}}-ca,{{word}}-au"

# Cities
alterx -l subdomains.txt -p "{{word}}-nyc,{{word}}-lon,{{word}}-sfo"

Integration with Other Tools

Pipeline with ShuffleDNS

# Generate wordlist and use it for DNS brute-forcing
alterx -l subdomains.txt -silent | shuffledns -d example.com -w /dev/stdin -r resolvers.txt

# Generate wordlist, filter, and use for DNS brute-forcing
alterx -l subdomains.txt -silent | grep -v "test" | shuffledns -d example.com -w /dev/stdin -r resolvers.txt

Pipeline with Subfinder

# Find subdomains passively and use them to generate wordlist
subfinder -d example.com -silent | alterx -p "{{word}}-dev,{{word}}-stage" -silent

# Find subdomains, generate wordlist, and use for DNS brute-forcing
subfinder -d example.com -silent | alterx -p "{{word}}-dev" -silent | shuffledns -d example.com -w /dev/stdin -r resolvers.txt

Pipeline with HTTPX

# Generate wordlist, resolve domains, and probe for HTTP services
alterx -l subdomains.txt -silent | dnsx -a -resp-only | httpx -silent

# Generate wordlist for specific domain and probe for HTTP services
alterx -l subdomains.txt -p "{{word}}-api" -silent | dnsx -a -resp-only -d example.com | httpx -silent

Output Customization

Custom Output Format

# Output only wordlist entries
alterx -l subdomains.txt -silent

# Count generated entries
alterx -l subdomains.txt -silent | wc -l

# Sort output alphabetically
alterx -l subdomains.txt -silent | sort

# Remove duplicates
alterx -l subdomains.txt -silent | sort -u

Filtering Output

# Filter by pattern
alterx -l subdomains.txt -silent | grep "dev"

# Filter out pattern
alterx -l subdomains.txt -silent | grep -v "test"

# Filter by length
alterx -l subdomains.txt -silent | awk 'length($0) < 20'

Advanced Filtering

# Filter by word count
alterx -l subdomains.txt -silent | awk 'NF==1'  # Single word
alterx -l subdomains.txt -silent | awk 'NF==2'  # Two words

# Filter by character type
alterx -l subdomains.txt -silent | grep -E '^[a-z]+$'  # Only lowercase
alterx -l subdomains.txt -silent | grep -E '[0-9]'     # Contains numbers

# Filter by domain pattern
alterx -l subdomains.txt -silent | grep -E '^api-'     # Starts with "api-"
alterx -l subdomains.txt -silent | grep -E '-dev$'     # Ends with "-dev"

Performance Optimization

Concurrency and Rate Limiting

# Set concurrency (default: 10)
alterx -l subdomains.txt -c 20

# Set rate limit
alterx -l subdomains.txt -rate-limit 100

Optimization for Large Inputs

# Use stream mode for large inputs
alterx -l large-subdomains.txt -stream

# Limit maximum entries
alterx -l subdomains.txt -max-entries 1000

Troubleshooting

Common Issues

1. Memory Issues

   # Use stream mode for large inputs
   alterx -l large-subdomains.txt -stream
   
   # Limit maximum entries
   alterx -l subdomains.txt -max-entries 1000

2. Pattern Issues

   # Check pattern syntax
   alterx -l subdomains.txt -p "{{word}}-dev" -debug
   
   # Use simple patterns first
   alterx -l subdomains.txt -p "{{word}}"

3. No Output

   # Check input file
   cat subdomains.txt
   
   # Use verbose mode
   alterx -l subdomains.txt -v

4. Duplicate Entries

   # Remove duplicates
   alterx -l subdomains.txt -silent | sort -u

Debugging

# Enable verbose mode
alterx -l subdomains.txt -v

# Show debug information
alterx -l subdomains.txt -debug

# Show statistics
alterx -l subdomains.txt -stats

Configuration

Configuration File

AlterX uses a configuration file located at $HOME/.config/alterx/config.yaml. You can customize various settings in this file:

# Example configuration file
concurrency: 10
rate-limit: 100
patterns:
  - "{{word}}-dev"
  - "{{word}}-stage"
  - "{{word}}-prod"

Environment Variables

# Set AlterX configuration via environment variables
export ALTERX_CONCURRENCY=10
export ALTERX_RATE_LIMIT=100
export ALTERX_PATTERNS="{{word}}-dev,{{word}}-stage,{{word}}-prod"

Reference

Command Line Options

Flag	Description
-d, -domain	Target domain(s) to use for wordlist generation
-l, -list	File containing list of domains to use for wordlist generation
-p, -pattern	Pattern(s) to use for wordlist generation
-pf, -pattern-file	File containing patterns to use for wordlist generation
-o, -output	File to write output to
-json	Write output in JSON format
-silent	Show only wordlist entries in output
-v, -verbose	Show verbose output
-extract-words	Extract words from input
-extract-numbers	Extract numbers from input
-extract-chars	Extract characters from input
-min-word-length	Minimum word length
-max-word-length	Maximum word length
-min-number-length	Minimum number length
-max-number-length	Maximum number length
-min-char-length	Minimum character length
-max-char-length	Maximum character length
-c, -concurrency	Number of concurrent workers
-rate-limit	Maximum number of entries per second
-stream	Stream mode for large inputs
-max-entries	Maximum number of entries to generate
-stats	Show statistics
-debug	Show debug information
-version	Show AlterX version

Pattern Variables

Variable	Description
	Extracts words from input
	Extracts numbers from input
	Extracts characters from input

Pattern Modifiers

Modifier	Description
:uppercase	Converts to uppercase
:lowercase	Converts to lowercase
:capitalize	Capitalizes first letter

Resources

• Official Documentation
• GitHub Repository
• Project Discovery Discord

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This cheat sheet provides a comprehensive reference for using AlterX, from basic wordlist generation to advanced pattern usage and integration with other tools. For the most up-to-date information, always refer to the official documentation.