Regex

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Regex (Regular Expressions) are a powerful tool for pattern matching and data analysis, widely used in penetration testing, development, and debugging. With regex, you can search, extract, and manipulate data efficiently, making it invaluable for tasks such as log analysis, input validation, and payload crafting.

This page provides an interactive form to generate and test regex commands tailored for penetration testing scenarios. The generated command updates dynamically as you define patterns, flags, and test input, allowing you to craft precise regex patterns on the fly.

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Key Features of This Tool

• Pattern Matching: Enter regex patterns to match specific text or data. Ideal for parsing logs, extracting credentials, or analyzing payloads.
• Flags for Enhanced Matching: Supports essential regex flags for penetration testers:
  • Global (/g): Search for all matches in the input text, not just the first one.
  • Case Insensitive (/i): Match patterns regardless of case.
  • Multiline (/m): Enable pattern matching across multiple lines of text.
  • Dotall (/s): Allows the dot (.) to match newline characters.
  • Unicode (/u): Ensures regex patterns properly interpret Unicode characters.
  • Sticky (/y): Matches text starting at the current position in the input.
• Interactive: Dynamically generates the regex pattern and flags as you modify the input, instantly reflecting the output.
• Command Output: Provides the shell command to execute your regex for real-world applications, enabling seamless integration into your workflows.

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Why Regex Matters for Penetration Testers
Regex is indispensable in cybersecurity for filtering, extracting, and analyzing data efficiently. It allows testers to craft precise patterns for targeting specific data, evading detection mechanisms, or analyzing large datasets.

Practical Uses of Regex in Pen Testing:

• Log Analysis: Search for error codes, IP addresses, or timestamps within large server logs.
• Credential Harvesting: Extract credentials or tokens from HTTP traffic or application responses.
• Payload Crafting: Develop complex patterns to identify and exploit input validation vulnerabilities.
• Filter Bypassing: Create obfuscated patterns to evade WAFs or IDS/IPS systems.

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Examples of Regex Commands:
Matching All IP Addresses in Logs:
Input:
192.168.0.1 connected to 10.0.0.1

Pattern:
\b(?:\d{1,3}\.){3}\d{1,3}\b

Flags:
/g

Command:
> echo '192.168.0.1 connected to 10.0.0.1' | grep -Po '\b(?:\d{1,3}\.){3}\d{1,3}\b'


Extracting Email Addresses:

Input:
Contact us at [email protected] or [email protected]

Pattern:
[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}

Flags:
/g /i

Command:
> echo 'Contact us at [email protected] or [email protected]' | grep -iPo '[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\\.[a-zA-Z]{2,}'


Finding Lines Starting with a Specific Word (Multiline Matching):

Input:
INFO: Connection established.
ERROR: Connection lost.
DEBUG: Retrying connection.


Pattern:
^ERROR:

Flags:
/m

Command:
> echo -e 'INFO: Connection established.\nERROR: Connection lost.\nDEBUG: Retrying connection.' | grep -Pm '^ERROR:'


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Practical Applications for Penetration Testers

• Evasion Techniques: Use regex to craft payloads that bypass input validation or security mechanisms.
• Efficient Data Analysis: Quickly locate and analyze critical information in logs, config files, or traffic captures.
• Automating Tasks: Generate regex patterns that can be directly integrated into scripts or command-line workflows for repeated use.

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Result Output
See your regex pattern and flags in action instantly. The tool also generates a shell command that you can copy, run, or modify, making it a perfect companion for any pen tester’s toolkit.