AbuseFilter
- AbuseFilter: Protecting Your Wiki from Vandalism and Harmful Content
Introduction
AbuseFilter is a powerful extension for MediaWiki that helps protect your wiki from vandalism, spam, and other harmful content. It automatically detects and flags potentially problematic edits based on predefined rules, allowing administrators and moderators to review and take appropriate action. This article will provide a comprehensive guide to AbuseFilter, covering its core concepts, configuration, rule creation, and best practices. This is aimed at beginners, assuming limited prior knowledge of the system. Understanding and utilizing AbuseFilter is crucial for maintaining a healthy and productive wiki environment.
Core Concepts
At its heart, AbuseFilter operates by evaluating edits against a set of defined rules. These rules consist of one or more *conditions* that, when met, trigger a specified *action*. Think of it like a checklist: if an edit matches the criteria on the checklist, something happens (like flagging the edit for review).
- **Edits:** AbuseFilter analyzes several aspects of an edit, including the text changes made, the user making the edit, and the page being edited.
- **Conditions:** These are the building blocks of a rule. They specify what to look for in an edit. Conditions can be based on regular expressions, variable comparisons, or a combination of both. Examples include checking for specific keywords, URLs, or patterns of behavior.
- **Actions:** These determine what happens when an edit matches a rule’s conditions. Common actions include flagging the edit for review, disallowing the edit entirely (blocking the user or reverting the change), or tagging the edit with a warning. Actions can be configured with varying levels of severity.
- **Variables:** AbuseFilter utilizes a wide array of variables that represent different aspects of an edit. These variables are used within conditions to define what to look for. Understanding these variables is key to writing effective rules. Some crucial variables include `$text` (the text being added or changed), `$user_name` (the username of the editor), `$page_title` (the title of the page being edited) and `$ip` (the IP address of the editor).
- **Filters:** A filter is a collection of rules. You can have multiple filters, each designed to address a specific type of abuse. It’s good practice to categorize filters logically (e.g., "Spam Filter", "Vandalism Filter", "Personal Attack Filter").
Installation and Setup
AbuseFilter is not enabled by default in MediaWiki. Installation typically requires downloading the extension from the MediaWiki Extensions repository (https://www.mediawiki.org/wiki/Extension:AbuseFilter) and installing it on your MediaWiki server. This usually involves:
1. Downloading the AbuseFilter extension files. 2. Uploading the files to the `/extensions/` directory of your MediaWiki installation. 3. Adding the following line to your `LocalSettings.php` file: `wfLoadExtension( 'AbuseFilter' );`. 4. Configuring AbuseFilter by setting appropriate values in `LocalSettings.php`. Key settings include the number of edits to consider for rate limits, the default action to take on a match, and the list of administrators who can manage the filter. 5. Running the update script to create the necessary database tables. This is typically done by visiting `https://yourwiki.com/w/index.php?title=Special:AbuseFilter/setup` in your browser.
Detailed installation instructions can be found on the official MediaWiki documentation page: [1](https://www.mediawiki.org/wiki/Extension:AbuseFilter/Installation).
Accessing the AbuseFilter Interface
After installation, you can access the AbuseFilter interface through the following special pages:
- `Special:AbuseFilter`: The main AbuseFilter control panel. This is where you can view, create, edit, and delete filters.
- `Special:AbuseFilter/log`: Displays a log of edits that have been flagged by AbuseFilter.
- `Special:AbuseFilter/history`: Shows the history of changes made to filters.
- `Special:AbuseFilter/setup`: The setup page used during initial installation, also useful for re-running the update scripts.
Administrators and users with the `abusefilter-log` permission can view the AbuseFilter log. Only users with the `abusefilter-modify` permission can create and edit filters. Carefully manage these permissions to ensure the integrity of your AbuseFilter configuration. Permissions are a critical aspect of wiki security.
Creating Your First Filter: A Simple Example
Let's create a simple filter to detect edits that contain the word "spam".
1. Navigate to `Special:AbuseFilter`. 2. Click "New filter". 3. **Filter Name:** "Spam Detection" 4. **Description:** "Detects edits containing the word 'spam'." 5. **Public Comments:** "This filter is designed to catch obvious spam attempts." 6. **Pre-save options:** Select "Do not automatically tag edits." (We’ll start with just logging) 7. **Conditions:**
* Condition 1: `$text` matches regex `spam` (case-insensitive). This means the filter will trigger if the text of the edit contains the word "spam", regardless of capitalization.
8. **Actions:**
* Action 1: `Flag edit`. This will flag the edit for review by administrators. * Action 2: `Tag edit as potentially harmful`.
9. Click "Save filter".
Now, any edit containing the word "spam" will be flagged for review in the AbuseFilter log. This is a basic example, but it demonstrates the fundamental process of creating a filter.
Understanding Variables and Regular Expressions
- **Variables:** AbuseFilter provides a rich set of variables. Some important ones include:
* `$text`: The text being added or changed. * `$user_name`: The username of the editor. * `$user_id`: The user ID of the editor. * `$page_title`: The title of the page being edited. * `$page_id`: The page ID of the page being edited. * `$ip`: The IP address of the editor. * `$timestamp`: The timestamp of the edit. * `$talk_page`: Boolean (true/false) indicating if the edit is to a talk page. * `$namespace`: The namespace of the page being edited. * `$article_length`: The length of the article after the edit. * `$edit_length`: The length of the edit itself.
A complete list of variables can be found in the MediaWiki documentation: [2](https://www.mediawiki.org/wiki/Extension:AbuseFilter/Variables).
- **Regular Expressions (Regex):** Regex is a powerful tool for pattern matching. AbuseFilter uses Perl-compatible regular expressions (PCRE). Learning regex is crucial for writing effective AbuseFilter rules. Here are some basic regex concepts:
* `.`: Matches any single character. * `*`: Matches the preceding character zero or more times. * `+`: Matches the preceding character one or more times. * `?`: Matches the preceding character zero or one time. * `[ ]`: Matches any character within the brackets. Example: `[aeiou]` matches any vowel. * `[^ ]`: Matches any character *not* within the brackets. Example: `[^0-9]` matches any non-digit. * `^`: Matches the beginning of a string. * `$`: Matches the end of a string. * `\d`: Matches a digit (0-9). * `\w`: Matches a word character (a-z, A-Z, 0-9, and _). * `\s`: Matches a whitespace character. * `|`: Represents "or". Example: `cat|dog` matches either "cat" or "dog". * `()`: Groups parts of the expression.
Resources for learning regex:
- [RegexOne](https://regexone.com/)
- [Regular-Expressions.info](https://www.regular-expressions.info/)
- [Regexr](https://regexr.com/) - an online regex tester.
Advanced Rule Creation: Combining Conditions and Actions
AbuseFilter allows you to combine multiple conditions using logical operators (`AND`, `OR`, `NOT`). You can also chain multiple actions together.
- Example: Detecting Link Spam**
Let's create a filter that detects edits containing a large number of external links.
1. **Filter Name:** "Link Spam Detection" 2. **Description:** "Detects edits containing an excessive number of external links." 3. **Conditions:**
* Condition 1: `$text` matches regex `\[http:\/\/[^\s\]]+\]`. This matches URLs enclosed in square brackets (the standard MediaWiki link format). * Condition 2: Count of matches from Condition 1 is greater than 5. (AbuseFilter provides functions for counting matches.)
4. **Actions:**
* Action 1: `Flag edit`. * Action 2: `Warn user`. (This requires configuring a warning template). * Action 3: `Throttle edits` - limit the number of edits this user can make in a short period.
This filter will flag edits that contain more than 5 external links, warn the user, and potentially throttle their editing privileges.
Using Rate Limits and Account Creation Restrictions
AbuseFilter can be used to implement rate limits, preventing users from making too many edits in a short period. This is useful for mitigating automated attacks and vandalism. You can also use AbuseFilter to restrict account creation based on various criteria.
- **Rate Limits:** Configure rate limits by specifying the maximum number of edits allowed within a given time frame. AbuseFilter can track edits based on user, IP address, or both. Consider using a combination of rate limits and other actions (e.g., flagging edits) for optimal protection.
- **Account Creation Restrictions:** AbuseFilter can prevent account creation if the username matches certain patterns (e.g., contains offensive words or is likely to be a bot). This can be configured in the filter settings.
Monitoring and Maintaining Your Filters
AbuseFilter requires ongoing monitoring and maintenance. Regularly review the AbuseFilter log to identify false positives (legitimate edits that were incorrectly flagged) and adjust your filters accordingly.
- **False Positives:** False positives are inevitable. When you encounter a false positive, analyze the edit and the filter that triggered it to understand why it was flagged. Modify the filter to be more specific or add exceptions to prevent similar false positives in the future.
- **Filter Updates:** As the types of abuse evolve, you’ll need to update your filters to address new threats. Stay informed about common vandalism techniques and spam tactics.
- **Performance:** Complex filters can impact wiki performance. Optimize your filters by using efficient regular expressions and minimizing the number of conditions.
- **Regular Expression Optimization:** Tools like [3](https://regex101.com/) can help you analyze and optimize your regular expressions for performance. Avoid overly complex expressions when simpler ones will suffice. Consider the use of character classes and anchors.
- **Analyzing Trends:** Pay attention to the types of abuse that are being flagged. Are there specific topics or pages that are being targeted? Are there common patterns in the abusive edits? This information can help you refine your filters and develop more effective protection strategies. Consider using web analytics tools to track trends.
Best Practices
- **Start Simple:** Begin with simple filters and gradually add complexity as needed.
- **Test Thoroughly:** Before enabling a new filter, test it thoroughly to ensure it doesn’t generate excessive false positives.
- **Document Your Filters:** Add clear and concise descriptions to your filters so that other administrators can understand their purpose.
- **Collaborate with Other Administrators:** Share your filters and knowledge with other administrators to improve the overall effectiveness of AbuseFilter.
- **Stay Updated:** Keep your AbuseFilter extension up to date to benefit from the latest security fixes and features.
- **Consider using a staging environment:** If possible, test new filters on a staging wiki before deploying them to your live wiki. This will help you identify and fix any issues without disrupting your users.
- **Utilize Whitelisting:** For trusted users or specific scenarios, consider whitelisting them to bypass certain filters. However, use this feature cautiously.
- **Leverage external threat intelligence:** Stay informed about current spam and vandalism techniques by consulting resources like [4](https://www.spamhaus.org/) and [5](https://www.cloudflare.com/learning/ddos/).
- **Monitor filter performance:** Regularly check the AbuseFilter log and system logs to ensure that your filters are not causing performance issues. Consider using performance monitoring tools.
- **Keep abreast of security vulnerabilities:** Stay informed about potential security vulnerabilities in MediaWiki and the AbuseFilter extension by subscribing to security mailing lists and monitoring security advisories.
- **Adopt a layered security approach:** AbuseFilter is just one component of a comprehensive security strategy. Combine it with other security measures, such as CAPTCHAs, strong password policies, and regular backups.
- **Understand the implications of each action:** Carefully consider the consequences of each action before enabling it. For example, blocking a user may prevent them from making legitimate edits.
- **Utilize the AbuseFilter API:** For advanced users, the AbuseFilter API allows you to programmatically access and manage AbuseFilter data. This can be useful for automating tasks and integrating AbuseFilter with other systems. [6](https://www.mediawiki.org/wiki/Extension:AbuseFilter/API)
- **Consider using a centralized AbuseFilter configuration:** For wikis that are part of a larger network, consider using a centralized AbuseFilter configuration to ensure consistency and simplify management.
- **Implement a reporting mechanism:** Provide a way for users to report suspected abuse to administrators. This can help you identify and address issues that may not be caught by AbuseFilter.
- **Review and update filters regularly:** Abuse tactics are constantly evolving, so it's important to review and update your filters regularly to ensure they remain effective. [7](https://www.owasp.org/) provides valuable resources on web application security.
- **Explore advanced regex techniques:** Learn about advanced regex techniques, such as backreferences and lookarounds, to create more powerful and precise filters.
- **Utilize the AbuseFilter extension's debugging features:** AbuseFilter provides debugging features that can help you troubleshoot issues and understand how your filters are working.
- **Leverage the AbuseFilter community:** Join the AbuseFilter community to share knowledge, ask questions, and learn from other administrators.
- **Explore the use of machine learning:** In the future, machine learning may be used to automate the creation and maintenance of AbuseFilter rules. [8](https://www.tensorflow.org/) and [9](https://scikit-learn.org/) are popular machine learning frameworks.
- **Consider the ethical implications of AbuseFilter:** Be mindful of the ethical implications of using AbuseFilter. Avoid creating filters that are overly restrictive or that discriminate against certain groups of users.
Special:MyPage is where you can manage your own user settings. Help:Contents provides general help with using the wiki. MediaWiki is the software powering this wiki. Extension is a way to add new features to MediaWiki. Spam is a common type of abuse that AbuseFilter can help prevent. Vandalism is another common type of abuse. Security is a critical aspect of wiki administration. Administration is the process of managing a wiki. Configuration is the process of setting up and customizing MediaWiki. Regular expression is a tool for pattern matching. Database is where wiki data is stored. Permissions control user access to features.
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