Sherlocked Security – Browser Security & Extension Audits
Hardening Enterprise Browser Environments and Ensuring Extension Hygiene
1. Statement of Work (SOW)
Service Name: Browser Security & Extension Audit
Client Type: Enterprises, Remote Workforce, Regulated Industries (Healthcare, Finance, Legal)
Service Model: Configuration Review, Extension Audit, Security Policy Enforcement
Compliance Coverage: NIST 800-53, HIPAA, PCI-DSS, ISO 27001, CIS Benchmarks
Assessment Types:
- Enterprise Browser Security Baseline Assessment
- Extension Permissions and Behavior Audit
- Browser Misconfiguration Detection
- Data Leakage Channel Discovery
- Compliance with Hardening Benchmarks
2. Our Approach
[Discovery Phase] → [Extension & Permission Inventory] → [Risk Analysis] → [Policy Tuning] → [Real-World Exploit Simulation] → [Recommendations & Controls] → [Revalidation]
3. Methodology
[Extension Enumeration] → [Permissions Analysis] → [Network & Script Behavior Logging] → [Policy Review] → [Threat Simulation] → [Risk Categorization] → [Remediation Advisory]
4. Deliverables to the Client
- Enterprise Browser Security Audit Report
- Extension Risk Scorecard (Malicious/Suspicious/Over-Permissioned)
- Behavioral Analysis of Browser Add-ons
- Recommendations for Secure Browser Configuration
- Sample Policies for Chrome Enterprise, Firefox ESR, Edge GPOs
- SIEM Integration Guidelines for Browser Telemetry
- Post-Fix Verification Report
- Optional: Blocklist/Allowlist Creation for Extensions
5. What We Need from You (Client Requirements)
- List of browsers used (Chrome, Edge, Firefox, etc.)
- List of approved or commonly used extensions
- Admin-level access to sample workstations or virtual test environments
- Access to browser configuration files or GPO templates
- Allowed domains, SaaS tools, and internal web applications
- NDA and scope agreement
6. Tools & Technology Stack
- Chrome Enterprise & Firefox ESR Policy Engines
- Burp Suite / MITM Proxy for Extension Traffic Analysis
- CRXcavator / Duo Extension Risk Analyzer
- OpenWPM & headless browser frameworks
- Browser DevTools & Extension Source Auditing
- GPO Templates, Intune Profiles, Jamf Pro (Mac)
- MITRE ATT&CK Mapping for Browser Tactics
- Threat simulation scripts for rogue extension behavior
7. Engagement Lifecycle
1. Scope Agreement & Discovery → 2. Extension Inventory → 3. Behavioral Logging & Network Capture → 4. Policy Gap Identification → 5. Extension Risk Categorization → 6. Remediation Report → 7. Final Policy Pack & Audit Closure
8. Why Sherlocked Security?
| Feature | Sherlocked Advantage |
|---|---|
| Real-Time Extension Behavior | Detects unauthorized network calls or DOM manipulation |
| CRX File Source Analysis | Decompiles and inspects CRX payloads for obfuscated/malicious code |
| Enterprise Policy Customization | GPO/Intune/MDM hardening templates provided for all major browsers |
| Zero Trust Readiness | Focus on least-privilege, device trust, and telemetry integration |
| Browser Exploit Simulation | Demonstrates real-world exploit paths via rogue extensions |
| Compliance Alignment | Matches output to CIS Benchmarks, PCI, HIPAA, NIST requirements |
9. Real-World Case Studies
Remote Workforce: Shadow IT via Unauthorized Extensions
Issue: Employees used unauthorized extensions that uploaded clipboard data to third-party servers.
Fix: Enterprise policy enforced install blocklist and allowed only vetted extensions.
Outcome: Reduced risk of data exfiltration and aligned with HIPAA compliance.
FinTech: Browser Misconfiguration & Insecure Defaults
Client: Web-based Banking Platform
Findings: LocalStorage accessible to untrusted scripts, auto-fill enabled on sensitive fields.
Solution: Hardened browser policy deployed via GPO, disabled risky features, reviewed extension behavior.
Outcome: Prevented credential leakage and improved PCI-DSS alignment.
10. SOP – Standard Operating Procedure
- Browser Usage Mapping Across Teams
- Inventory of Installed Extensions via Scripts or MDM
- Source Analysis of Each Extension (CRX, Web Store ID)
- Capture Background Network Traffic During Typical Use
- Review Extension Permissions and Match with Use Case
- Simulate Malicious Behaviors via Test Extensions
- Review Browser Features (e.g., auto-fill, password manager, dev tools access)
- Recommend Enterprise Hardening Policies
- Provide Blocklists/Allowlists and Monitoring Scripts
- Final Audit & Risk Matrix Delivery
11. Browser & Extension Audit Checklist
1. Extension Inventory & Metadata Analysis
- Enumerate all installed extensions across sample endpoints
- Capture Web Store IDs, CRX hashes, and version history
- Analyze manifest.json for declared permissions
- Check update URLs for insecure or self-hosted sources
- Cross-reference with known bad/malicious extension lists (CRXcavator, Web of Trust)
- Identify extensions using broad permissions (
*://*/*,tabs,clipboardWrite, etc.)
2. Behavioral and Network Activity Monitoring
- Enable network logging to monitor extension-initiated requests
- Use MITM proxy to inspect domains contacted by extensions
- Log DOM modifications or event listeners added by extensions
- Monitor background scripts and service workers for suspicious activity
- Simulate user interaction to trigger dormant behaviors
3. Permissions Audit & Risk Categorization
- Compare requested vs. required permissions for actual function
- Flag redundant or excessive permissions (access to
bookmarks,history,storage) - Classify extensions into Safe, Medium-Risk, and High-Risk categories
- Document API usage (e.g., chrome.tabs.executeScript, webRequest, eval usage)
- Evaluate extension’s ability to bypass CSP or inject into sensitive sites
4. Enterprise Configuration & Hardening
- Enforce allowlists (
ExtensionInstallAllowlist) for approved extensions - Enable install blocklists (
ExtensionInstallBlacklist) - Disable Chrome Developer Tools on non-admin users
- Block password manager, autofill, and credit card storage in browser settings
- Apply Safe Browsing and sandboxing policies
- Configure telemetry forwarding of browser events to SIEM or endpoint tools
5. Browser Security Feature Audit
- Check if Safe Browsing is enabled
- Validate certificate transparency enforcement
- Review mixed content behavior (block vs. warn)
- Audit localStorage/sessionStorage exposure policies
- Ensure pop-ups, cross-origin frames, and insecure forms are disabled
- Disable or limit WebRTC unless explicitly required
6. Threat Simulation & Exploit Testing
- Deploy test extensions that simulate clipboard stealing or keylogging
- Validate whether browser policies block suspicious behaviors
- Try exfiltration of sensitive DOM data (e.g., credentials, form input)
- Inject fake CRX files and verify installation controls
- Test login hijack scenarios via autofill + phishing iframe
- Evaluate ability of extensions to alter page content or form submissions
7. Post-Audit Remediation & Policy Design
- Provide enterprise-ready GPOs or JSON configs for Chrome, Firefox, Edge
- Recommend browser hardening settings per role/team
- Supply continuous monitoring script templates (e.g., PowerShell, Jamf)
- Offer education content for employee extension hygiene
- Reassess risk quarterly or after major browser updates