New ‘Loop DoS’ attack may impact up to 300,000 online systems

A new denial-of-service attack dubbed 'Loop DoS' targeting application layer protocols can pair network services into an indefinite communication loop that creates large volumes of traffic. Devised by researchers at the CISPA Helmholtz-Center for Information Security, the attack uses the User Datagram Protocol (UDP) and impacts an estimated 300,000 host and their networks. The attack is possible due to a vulnerability, currently tracked as CVE-2024-2169, in the implementation of the UDP protocol, which is susceptible to IP spoofing and does not provide sufficient packet verification. An attacker exploiting the vulnerability creates a self-perpetuating mechanism that generates excessive traffic without limits and without a way to stop it, leading to a denial-of-service (DoS) condition on the target system or even an entire network. Loop DoS relies on IP spoofing and can be triggered from a single host that sends one message to start the communication. According to the Carnegie Mellon CERT Coordination Center (CERT/CC) there are three potential outcomes when an attacker leverages the vulnerability: CISPA researchers Yepeng Pan and Professor Dr. Christian Rossow say the potential impact is notable, spanning both outdated (QOTD, Chargen, Echo) and modern protocols (DNS, NTP, TFTP) that are crucial for basic internet-based functions like time synchronization, domain name resolution, and file transfer without authentication. "If two application servers have a vulnerable implementa...