Record-Breaking DDoS Attack: 37.4TB Barrage Blocked by Cloudflare

Cloudflare recently mitigated a colossal Distributed Denial of Service (DDoS) attack, the largest ever recorded. This cyber assault bombarded a single IP address with a staggering 37.4 terabytes of data in just 45 seconds.

Unprecedented Scale: Equivalent to Thousands of HD Movies

To put the magnitude of this attack into perspective, 37.4TB is roughly equivalent to streaming nearly 10,000 high-definition movies. The speed at which this data was delivered is what makes this attack truly exceptional.

Attack Vectors: UDP Floods and Reflection Amplification

The attackers employed multiple techniques, with a primary focus on User Datagram Protocol (UDP) floods. UDP, known for its speed, doesn’t require a handshake before sending data, making it a favored tool for DDoS attacks. The perpetrators also utilized reflection/amplification attacks, spoofing the target’s IP address to request information from third-party services, overwhelming the victim with responses.

DDoS Attacks: A Persistent Threat

While protections exist to mitigate DDoS attacks, threat actors continue to leverage botnets comprising numerous compromised devices. These attacks are a relatively inexpensive method to test defenses or even extort online businesses.

Past Record-Breaking Attacks

This recent event follows a series of increasingly large DDoS attacks. Microsoft faced a 3.47 Tbps attack in January 2022, which was later surpassed by a 5.6 Tbps attack in East Asia in October 2024. In April 2025, Cloudflare reported a 6.5 Tbps attack lasting almost 49 seconds.

Cloudflare’s successful mitigation of this 37.4TB DDoS attack highlights the ongoing battle against cyber threats and the importance of robust security measures.

Source: Tom’s Hardware