MITM Detector by Stan Wijckmans
A Firefox extension that detects potential Man-in-the-Middle (MITM) attacks by monitoring TLS certificate issuers and alerting when suspicious or blacklisted certificate authorities are encountered.
Extension Metadata
About this extension
MITM Detector inspects the certificate chain of every HTTPS connection and cross-references the issuing certificate authority against a blacklist of known or suspicious issuers. When a suspicious issuer is detected, the extension displays a notification alerting the user to a potential interception attack.
A certificate issuer can be added to the blacklist by adding its Distinguished Name (DN) to the list on the extension's settings page.
A certificate issuer can be added to the blacklist by adding its Distinguished Name (DN) to the list on the extension's settings page.
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Permissions and data
Required permissions:
- Display notifications to you
- Access browser tabs
Optional permissions:
- Access your data for all websites
Data collection:
- The developer says this extension doesn't require data collection.
More information
- Add-on Links
- Version
- 1.0.1
- Size
- 11.83 KB
- Last updated
- 2 months ago (Apr 27, 2026)
- Related Categories
- License
- MIT License
- Version History
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