Arachni - Web Application Security Scanner Framework

Version 1.0.3
Code Documentation
Author Tasos Laskos (@Zap0tek)
Twitter @ArachniScanner
Copyright 2010-2014 Tasos Laskos
License Dual-licensed (Apache License v2.0/Commercial) - (see LICENSE file)

Arachni logo


Arachni is an Open Source, feature-full, modular, high-performance Ruby framework aimed towards helping penetration testers and administrators evaluate the security of web applications.

It is smart, it trains itself by monitoring and learning from the web application's behavior during the scan process and is able to perform meta-analysis using a number of factors in order to correctly assess the trustworthiness of results and intelligently identify (or avoid) false-positives.

Unlike other scanners, it takes into account the dynamic nature of web applications, can detect changes caused while travelling through the paths of a web application’s cyclomatic complexity and is able to adjust itself accordingly. This way, attack/input vectors that would otherwise be undetectable by non-humans can be handled seamlessly.

Moreover, due to its integrated browser environment, it can also audit and inspect client-side code, as well as support highly complicated web applications which make heavy use of technologies such as JavaScript, HTML5, DOM manipulation and AJAX.

Finally, it is versatile enough to cover a great deal of use cases, ranging from a simple command line scanner utility, to a global high performance grid of scanners, to a Ruby library allowing for scripted audits, to a multi-user multi-scan web collaboration platform.

Note: Despite the fact that Arachni is mostly targeted towards web application security, it can easily be used for general purpose scraping, data-mining, etc. with the addition of custom components.

Arachni offers:

A stable, efficient, high-performance framework

Check, report and plugin developers are allowed to easily and quickly create and deploy their components with the minimum amount of restrictions imposed upon them, while provided with the necessary infrastructure to accomplish their goals.

Furthermore, they are encouraged to take full advantage of the Ruby language under a unified framework that will increase their productivity without stifling them or complicating their tasks.

Moreover, that same framework can be utilized as any other Ruby library and lead to the development of brand new scanners or help you create highly customized scan/audit scenarios and/or scripted scans.


Although some parts of the Framework are fairly complex you will never have to deal them directly. From a user’s or a component developer’s point of view everything appears simple and straight-forward all the while providing power, performance and flexibility.

From the simple command-line utility scanner to the intuitive and user-friendly Web interface and collaboration platform, Arachni follows the principle of least surprise and provides you with plenty of feedback and guidance.

In simple terms

Arachni is designed to automatically detect security issues in web applications. All it expects is the URL of the target website and after a while it will present you with its findings.



Integrated browser environment

Arachni includes an integrated, real browser environment in order to provide sufficient coverage to modern web applications which make use of technologies such as HTML5, JavaScript, DOM manipulation, AJAX, etc.

In addition to the monitoring of the vanilla DOM and JavaScript environments, Arachni's browsers also hook into popular frameworks to make the logged data easier to digest:

In essence, this turns Arachni into a DOM and JavaScript debugger, allowing it to monitor DOM events and JavaScript data and execution flows. As a result, not only can the system trigger and identify DOM-based issues, but it will accompany them with a great deal of information regarding the state of the page at the time.

Relevant information include:

In essence, you have access to roughly the same information that your favorite debugger (for example, FireBug) would provide, as if you had set a breakpoint to take place at the right time for identifying an issue.


The browser-cluster is what coordinates the browser analysis of resources and allows the system to perform operations which would normally be quite time consuming in a high-performance fashion.

Configuration options include:


The system can provide great coverage to modern web applications due to its integrated browser environment. This allows it to interact with complex applications that make heavy use of client-side code (like JavaScript) just like a human would.

In addition to that, it also knows about which browser state changes the application has been programmed to handle and is able to trigger them programatically in order to provide coverage for a full set of possible scenarios.

By inspecting all possible pages and their states (when using client-side code) Arachni is able to extract and audit the following elements and their inputs:

Open distributed architecture

Scope configuration



Arachni is a highly modular system, employing several components of distinct types to perform its duties.

In addition to enabling or disabling the bundled components so as to adjust the system's behavior and features as needed, functionality can be extended via the addition of user-created components to suit almost every need.

Platform fingerprinters

In order to make efficient use of the available bandwidth, Arachni performs rudimentary platform fingerprinting and tailors the audit process to the server-side deployed technologies by only using applicable payloads.

Currently, the following platforms can be identified:

The user also has the option of specifying extra platforms (like a DB server) in order to help the system be as efficient as possible. Alternatively, fingerprinting can be disabled altogether.

Finally, Arachni will always err on the side of caution and send all available payloads when it fails to identify specific platforms.


Checks are system components which perform security checks and log issues.


Active checks engage the web application via its inputs.


Passive checks look for the existence of files, folders and signatures.



Plugins add extra functionality to the system in a modular fashion, this way the core remains lean and makes it easy for anyone to add arbitrary functionality.


Default plugins will run for every scan and are placed under /plugins/defaults/.


Plugins under /plugins/defaults/meta/ perform analysis on the scan results to determine trustworthiness or just add context information or general insights.

Trainer subsystem

The Trainer is what enables Arachni to learn from the scan it performs and incorporate that knowledge, on the fly, for the duration of the audit.

Checks have the ability to individually force the Framework to learn from the HTTP responses they are going to induce.

However, this is usually not required since Arachni is aware of which requests are more likely to uncover new elements or attack vectors and will adapt itself accordingly.

Still, this can be an invaluable asset to Fuzzer checks.



Running the specs

You can run rake spec to run all specs or you can run them selectively using the following:

rake spec:core            # for the core libraries
rake spec:checks          # for the checks
rake spec:plugins         # for the plugins
rake spec:reports         # for the reports
rake spec:path_extractors # for the path extractors

Please be warned, the core specs will require a beast of a machine due to the necessity to test the Grid/multi-Instance features of the system.

Note: The check specs will take about 90 minutes due to the timing-attack tests.

Bug reports/Feature requests

Submit bugs using GitHub Issues and get support via the Support Portal.


(Before starting any work, please read the instructions for working with the source code.)

We're happy to accept help from fellow code-monkeys and these are the steps you need to follow in order to contribute code:


Dual-licensed (Apache License v2.0/Commercial) -- please see the LICENSE file for more information.


This is free software and you are allowed to use it as you see fit. However, neither the development team nor any of our contributors can be held responsible for your actions nor for any damage caused by the use of this software.