CyberDrain has released Check, a free open source browser extension that blocks phishing attempts in Microsoft 365, giving MSPs a transparent, community-driven defence beyond email filters.
CyberDrain, the MSP-focused developer behind the widely-used CIPP platform, has launched Check, a free and open-source browser extension designed to block phishing attacks targeting Microsoft 365 and Entra.
Unlike conventional anti-phishing tools that rely on email protection or server-side filters, Check works inside the browser, stopping credential entry on known or suspected phishing pages. The extension completely blocks access, notifies users, and alerts administrators—without collecting personal data, since all analysis is performed locally. Silent deployment ensures users do not need training or behaviour change, while full white-labelling allows MSPs to brand the tool as their own.
CyberDrain is positioning Check as a community-driven open-source project, inviting vendors, MSPs, and researchers to contribute improvements. Support has already come from security researchers and partners such as NinjaOne. Future versions are planned to expand protection beyond Microsoft 365 and Entra, extending coverage to SaaS platforms such as HubSpot, Salesforce and CRMs.
Kelvin Tegelaar, founder of CyberDrain, said: “Most anti-phishing tools stop the attack at the email. That’s fantastic. But phishing doesn’t just come from email anymore. People get phone calls, SMS messages, social DMs with malicious links. Browser protection gives you that second line of defence, after the link is clicked, when traditional email filters can’t help anymore.”
Ashley Cooper, CyberDrain COO, highlighted the value of open source: “Trust is everything. People want to get hands-on and see how things work. That transparency helps build a sense of ownership, of contribution, and that brings more community engagement and more trust.”
Logan Cook, CTO of MSP Bezalu, added: “Check covers a critically essential piece of cybersecurity that most MSPs completely neglect. Sure, there are other options out there, but none as flexible, controllable and free as this.”
