Is "CSPBlocker" on Firefox Add-ons Safe to Install?
The goal of this extension is to gain back control over your browser by blocking web features a website doesn't need. For now, it supports these features: Web Fonts This blocks any custom web fonts a website may ask for. It's blocked by adding an additional content-security-policy with font-src set to 'none'. Objects (Java / Flash) This blocks any object a website might try to load. This includes java and flash applets. Again this is achieved with a content-security-policy, by setting object-src to 'none'. Reporting apis This blocks any reporting a website might want to do. This can include netwerk issues, content security policy violations, and more. We achieve this by removing the report-to and content-security-policy-report-only headers from any sub/main frame requests. In addition, any content security policy report gets blocked and never sent to the websites server. Workers This blocks any workers a website may ask for. This can be used to block serviceworkers, which can be used to spam the user with notifications, keep running in the background and more. This is blocked by setting worker-src to 'none' in the content-security-policy header. This extension is still in development. In the future, you will be able to select what features it should or should not be blocking. In addition, further controls will be added so you can control what websites should receive what exceptions.
Risk Assessment
Analyzed27 security findings detected across all analyzers
Firefox extension requesting 4 permissions
Severity Breakdown
Finding Categories
YARA Rules Matched
5 rules(6 hits)Requested Permissions
4 permissionsAccess and modify data on every website you visit
Intercept, modify, and block all network requests
Block network requests before they complete
About This Extension
Detailed Findings
7 totalYARA Rule Matches
5 rulesIndicators of Compromise
Network indicators, suspicious strings, and potential IoCs extracted during analysis
All Indicators · 19
detected Domain: signingca1.addons.mozilla.org XIOC detected Domain: signingca1.addons.mozilla.org
extracted_from_files
detected URL: https://apps.jeurissen.co XIOC detected URL: https://apps.jeurissen.co
extracted_from_files
detected URL: http://www.w3.org/2000/svg XIOC detected URL: http://www.w3.org/2000/svg
extracted_from_files
detected URL: https://apps.jeurissen.co/ XIOC detected URL: https://apps.jeurissen.co/
extracted_from_files
detected MD5 Hash: f0376d38d065353fe43f2c7b4f247977 XIOC detected MD5 Hash: f0376d38d065353fe43f2c7b4f247977
extracted_from_files
detected Domain: date.now XIOC detected Domain: date.now
extracted_from_files
detected Domain: www.w3.org XIOC detected Domain: www.w3.org
extracted_from_files
detected Domain: t.name XIOC detected Domain: t.name
extracted_from_files
detected Domain: e.target XIOC detected Domain: e.target
extracted_from_files
detected Domain: e.name XIOC detected Domain: e.name
extracted_from_files
detected URL: http://addons.mozilla.org/ca/crl.pem0N XIOC detected URL: http://addons.mozilla.org/ca/crl.pem0N
extracted_from_files
detected Domain: mozilla.com XIOC detected Domain: mozilla.com
extracted_from_files
detected Domain: addons.mozilla.org XIOC detected Domain: addons.mozilla.org
extracted_from_files
detected Domain: content-signature.mozilla.org XIOC detected Domain: content-signature.mozilla.org
extracted_from_files
detected Domain: carlosjeurissen.com XIOC detected Domain: carlosjeurissen.com
extracted_from_files
detected Domain: t7aca1a5c836d2e740723531095377a59.f0376d38d065353fe43f2c7b4f247977.addons.mozilla.org XIOC detected Domain: t7aca1a5c836d2e740723531095377a59.f0376d38d065353fe43f2c7b4f247977.addons.mozilla.org
extracted_from_files
detected Domain: window.open XIOC detected Domain: window.open
extracted_from_files
detected Domain: apps.jeurissen.co XIOC detected Domain: apps.jeurissen.co
extracted_from_files
Security Analysis Summary
Security Analysis Overview
CSPBlocker is a Firefox Add-ons extension published by Jeurissen Apps. Version 0.0.5 has been analyzed by the Risky Plugins security platform, receiving a risk score of 49.45/100 (MEDIUM risk) based on 27 security findings.
Risk Assessment
This extension presents moderate security risk. Several findings were detected that may warrant attention. Users should carefully review the permissions and findings before installation.
Findings Breakdown
- High: 6 finding(s)
- Medium: 21 finding(s)
What Was Analyzed
The security assessment covers multiple analysis categories:
- Malware Detection: YARA rule matching against 2,400+ malware signatures
- Secret Detection: Scanning for exposed API keys, tokens, and credentials
- Static Analysis: Code-level security analysis for common vulnerability patterns
- Network Analysis: Detection of suspicious network communications and endpoints
- Obfuscation Detection: Identification of code obfuscation techniques
Developer Information
CSPBlocker is published by Jeurissen Apps on the Firefox Add-ons marketplace. The extension has approximately 33 users.
Recommendation
Exercise caution with this extension. Review the detailed findings and ensure the requested permissions align with the extension's stated functionality before installation.
Source Code Not Available
Source code is not available for this version of the extension.
Frequently Asked Questions
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