Full Report
Brave has open-sourceed a new tool called "Cookiecrumbler," which uses large language models (LLMs) to detect cookie consent notices and then community-driven reviews to block those that won't break site functionality. [...]
Analysis Summary
# Tool/Technique: Cookiecrumbler
## Overview
Cookiecrumbler is a tool developed by Brave that leverages community input and AI to detect and suggest fixes for blocking intrusive cookie consent management platform (CMP) notices on websites. Its primary purpose is to improve user experience by blocking these notices while minimizing functionality breaks on websites caused by overly aggressive blocking rules.
## Technical Details
- Type: Tool
- Platform: Backend analysis tool (uses Puppeteer for web interaction)
- Capabilities: Large-scale, regionally aware cookie banner detection, classification using LLM, community-driven triage, and generation of filter suggestions.
- First Seen: Not explicitly stated in the context, but recently announced as part of Brave's privacy initiatives.
## MITRE ATT&CK Mapping
This tool is focused on improving user experience and privacy protection against common web annoyances (cookie notices) and does not directly map to offensive TTPs. However, in a conceptual sense related to **Defense Evasion** or **Collection** against web administrators, it functions more akin to web auditing/scanning:
- **TA0005 - Defense Evasion** (Conceptual relevance to bypassing website implementation)
- T1598 - Tailor Social Engineering (Conceptual relevance to tailoring remediation efforts)
## Functionality
### Core Capabilities
- **Crawling:** Crawls top websites using regional proxies to simulate browsing from different geographical locations.
- **Detection:** Loads pages using Puppeteer to programmatically identify potential cookie consent notices.
- **Classification:** Uses a Large Language Model (LLM) to classify the detected notices and generate suggestions for fixing or blocking them without breaking site functionality.
- **Community Triage:** Publishes detection results as GitHub issues for community review and improvement of filter rules.
### Advanced Features
- **Regional Awareness:** Performs detection using regional proxies to account for different compliance requirements or deployments across locales.
- **False Positive Reduction:** Manual review of suggestions is performed before application to avoid breaking essential website functionality (e.g., checkout flows, scrolling).
- **Privacy Preservation:** Operates entirely on Brave's backend; does not interact with user browser sessions or expose sensitive user data.
- **Open Source:** The tool is open-source and freely available on GitHub for use by other privacy tool developers, auditors, or users.
## Indicators of Compromise
*Since this is a defense/auditing tool developed by Brave, traditional malware IOCs do not apply.*
- File Hashes: N/A (Open-source tool code)
- File Names: N/A
- Registry Keys: N/A
- Network Indicators: N/A (Uses public site lists like Tranco for target selection)
- Behavioral Indicators: N/A
## Associated Threat Actors
- Brave Software (Developer)
- Privacy tool developers, adblock list maintainers, and tech-savvy users (Potential users of the open-source code).
## Detection Methods
*Detection is not applicable as this is a benign, white-hat tool.*
- Signature-based detection: N/A
- Behavioral detection: N/A
- YARA rules if available: N/A
## Mitigation Strategies
*Mitigation is not applicable as this tool is designed for defense/improvement.*
- Prevention measures: N/A
- Hardening recommendations: N/A
## Related Tools/Techniques
- Ad-blocking filter lists (e.g., EasyList) which operate on similar principles to block website elements.
- Web crawlers/scrapers utilizing headless browsers like Puppeteer for automated interaction.