New 'Loop DoS' Attack Impacts Hundreds of Thousands of Systems

Researchers from CISPA disclosed a novel "Loop DoS" attack that abuses UDP-based application protocols (e.g., DNS, NTP, TFTP, Chargen, Echo) by spoofing source IPs to pair vulnerable servers so they endlessly exchange error responses, creating self-sustaining denial-of-service traffic. The study estimates roughly 300,000 hosts can be abused, identifies multiple affected products/vendors, warns the technique is trivial to trigger from a spoofing-capable host, and recommends anti-spoofing measures such as BCP38; there is currently no evidence of in-the-wild exploitation.