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Cromite includes a built-in modified AdBlock Plus engine with enhanced capabilities including DNS CNAME support, WebSocket blocking, and automatic filter updates.

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Modified AdBlock Plus Engine

Cromite uses a modified version of AdBlock Plus that has been enhanced for better privacy and security while removing some potentially dangerous features.

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Engine Modifications

The following AdBlock Plus features have been removed for security reasons:
  • Header and CSP filter option - Removed for security
  • json-override snippet - Removed to prevent script injection
  • simulate-event-poc snippet - Removed to prevent event simulation abuse
  • simulate-mouse-event snippet - Removed to prevent mouse event abuse
  • Sitekey support - Removed for simplicity
  • override-property-read snippet - Modified to allow only 0 and 1 as numeric arguments (prevents arbitrary value injection)
Cromite adds several powerful features to the AdBlock Plus engine:
  • DNS CNAME support - Uncovers tracking domains hidden behind CNAME records
  • WebSocket blocking - Blocks WebSocket connections used for tracking
  • WebTransport blocking - Blocks WebTransport URLs
  • Service Worker fetch blocking - Blocks service worker network requests

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CNAME Uncloaking

One of Cromite’s most powerful ad blocking features is CNAME uncloaking. Many trackers hide behind CNAME DNS records to evade ad blockers. Cromite resolves CNAME records to identify and block these hidden trackers.

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How CNAME Uncloaking Works

When a website loads content from analytics.example.com, that domain might be a CNAME pointing to tracker.adnetwork.com. Traditional ad blockers only see the first domain. Cromite’s CNAME support resolves the chain and blocks based on the final destination. Example: 
analytics.example.com (appears legitimate)
  → CNAME: metrics.cdn.com
    → CNAME: tracker.adnetwork.com (blocked!)

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WebSocket and WebTransport Blocking

Cromite can block WebSocket and WebTransport connections, which are increasingly used for tracking and real-time bidding in advertising.
Traditional ad blockers struggle with WebSocket connections because they bypass normal HTTP request filtering. Cromite’s modified engine blocks these at the protocol level. Blocked protocols:
  • ws:// and wss:// (WebSocket)
  • WebTransport URLs
  • Service Worker fetch requests

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Gateway Attack Prevention

Cromite specifically blocks gateway attacks via WebSockets - a technique where malicious sites establish WebSocket connections to internal network resources.

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Filter Lists

Cromite downloads filter lists from www.cromite.org/filters URLs.

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Adding Custom Filter Lists

1

Navigate to AdBlock Settings

Open chrome://adblock in your address bar
2

Add Filter List URL

Enter HTTPS URLs to custom filter lists
HTTP URL redirection is prohibited for security. Only HTTPS filter list URLs are allowed.
3

Save and Update

Filter lists will be downloaded and applied immediately

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Update Mechanism

The Cromite AdBlock Update Service provides automatic filter updates to ensure you’re protected against the latest ads and trackers.

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Update Schedule

  • Frequency: Daily checks for new filters
  • Source: www.cromite.org/filters
  • Privacy: www.cromite.org does not record any logs during filter updates
  • Automatic: Updates happen in the background without user interaction

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Manual Updates

You can manually trigger a filter update from chrome://adblock.

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Configuration

Access the AdBlock configuration page to customize filtering behavior:

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chrome://adblock

The AdBlock configuration page allows you to:

Manage Filter Lists

Add, remove, and update filter list subscriptions

Custom Filters

Add your own custom filter rules

Whitelist Domains

Allow ads on specific domains

View Statistics

See how many requests have been blocked

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Site Settings Integration

Cromite integrates ad blocking with Chrome’s site settings system.

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Per-Site AdBlock Control

1

Open Site Settings

Navigate to chrome://settings/content/adblock or click the lock icon in the address bar
2

Configure for Site

Enable or disable ad blocking for the current site
3

Set Default Behavior

Configure the default ad blocking behavior for all sites
The site settings integration allows you to easily whitelist specific sites while maintaining strong ad blocking everywhere else.

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Content Settings

Cromite provides granular content settings for ad blocking:
  • Adblock - Main ad blocking toggle
  • Cookies - Cookie blocking (works with ad blocker)
  • JavaScript - JavaScript blocking (extreme privacy)
  • Images - Image blocking (reduces bandwidth)
  • Autoplay - Autoplay blocking (prevents video ads)
  • Pop-ups - Pop-up blocking (enabled by default)

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All Pop-ups Blocking

Cromite enables blocking of ALL pop-ups by default, including those that would normally bypass Chrome’s pop-up blocker.

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Limitations

Important limitations of Cromite’s ad blocking engine:

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No CSS Rules Support

The current AdBlock Plus engine implementation does not support CSS-based filtering rules. This means:
  • Cosmetic filtering is limited
  • Some ads may still be visible (but network requests are blocked)
  • Element hiding rules are not applied
Impact: You may see empty ad containers on some sites. The tracking requests are blocked, but the visual elements may remain.

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Filter List Compatibility

Not all AdBlock Plus filter lists are fully compatible due to removed features:
  • Lists using header or csp options won’t work
  • Lists using removed snippets will have those rules skipped
  • Most standard filter lists work fine

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Legacy Bromite Engine

Cromite also includes the legacy Bromite ad blocking engine (disabled by default).
Since v77, Bromite used Chromium’s built-in subresource filter. This engine:
  • Uses Chromium’s native subresource filter
  • Does not support CSS rules
  • Less powerful than the AdBlock Plus engine
  • Disabled by default in Cromite
  • Checks for updates weekly (legacy behavior)
Note: The legacy engine is maintained for compatibility but the AdBlock Plus engine is recommended.

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Privacy Benefits

Ad blocking provides significant privacy benefits beyond removing visual clutter:

Tracking Prevention

Blocks tracking pixels, beacons, and analytics scripts

Fingerprinting Reduction

Prevents fingerprinting scripts from loading

Malware Protection

Blocks malicious advertising networks

Bandwidth Savings

Reduces data usage by blocking large ad content

Performance

Pages load faster without ad network requests

Battery Life

Reduces CPU usage from ad scripts and animations

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Performance Impact

Cromite’s ad blocking has minimal performance impact:
  • Filter list parsing happens at startup
  • Blocking decisions are made at the network layer
  • No CSS parsing overhead (due to lack of cosmetic filtering)
  • CNAME resolution adds minimal latency
  • WebSocket blocking is protocol-level

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Troubleshooting

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Site Breaking

If a site breaks due to ad blocking:
1

Check if AdBlock is the cause

Temporarily disable ad blocking for the site via chrome://adblock
2

Whitelist the domain

Add the domain to your whitelist if it requires ads to function
3

Report false positives

Report overly aggressive blocking to the filter list maintainers

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Filter Updates Not Working

If filter updates aren’t working:
  1. Check your internet connection
  2. Verify www.cromite.org is not blocked by a firewall
  3. Manually trigger an update from chrome://adblock
  4. Check for error messages in chrome://adblock

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Best Practices

Recommended configuration:
  1. Keep the default filter lists enabled
  2. Enable automatic updates (default)
  3. Only whitelist sites you trust
  4. Use HTTPS-only filter lists
  5. Combine with privacy features for maximum protection

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