New Blast-RADIUS attack breaks 30-year-old protocol used in networks everywhere

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One of the most widely used network protocols is vulnerable to a newly discovered attack that can allow adversaries to gain control over a range of environments, including industrial controllers, telecommunications services, ISPs, and all manner of enterprise networks.

Short for Remote Authentication Dial-In User Service, RADIUS harkens back to the days of dial-in Internet and network access through public switched telephone networks. It has remained the de facto standard for lightweight authentication ever since and is supported in virtually all switches, routers, access points, and VPN concentrators shipped in the past two decades. Despite its early origins, RADIUS remains an essential staple for managing client-server interactions for:

VPN access
DSL and Fiber to the Home connections offered by ISPs,
Wi-Fi and 802.1X authentication
2G and 3G cellular roaming
5G Data Network Name authentication
Mobile data offloading
Authentication over private APNs for connecting mobile devices to enterprise networks
Authentication to critical infrastructure management devices
Eduroam and OpenRoaming Wi-Fi

RADIUS provides seamless interaction between clients—typically routers, switches, or other appliances providing network access—and a central RADIUS server, which acts as the gatekeeper for user authentication and access policies. The purpose of RADIUS is to provide centralized authentication, authorization, and accounting management for remote logins.