Small bit-and-piece DDoS attacks (distributed denial of service) boomed by 233% in the first half of 2021, according to Nexusguard researchers in the Threat Report FHY 2021.

As the pandemic carried on into 2021, hackers experimented with new attack patterns to avoid signature-based detection.

In the first half of 2021, more than 99% of all DDoS attacks were smaller than 10Gbps, as Nexusguard had predicted in 2020. These small, nimble attacks can cripple communications service providers (CSPs) and Internet service providers (ISPs) if they leave detection to threshold or signature-based methods alone.

Attackers are continuing to diversify their approaches with bit-and-piece attacks to bring down target networks and infrastructures. More than 95% of attacks were smaller than 1Gbps each, of which Nexusguard analysts believe a majority were launched using readily available and inexpensive DDoS-for-hire services.

Rather than launching large bandwidth attacks against their targets, researchers noted that perpetrators chose to employ attacks using high packet-rate loads of small-sized traffic from DDoS-for-hire services, with the aim of evading DDoS mitigation detection systems.

“The high level of intricacies behind communications service provider networks causes them to generally allow all types of traffic to pass through, which leads to smaller or spoofed types of attacks to strike undetected,” says Juniman Kasman, chief technology officer of Nexusguard. “Behavioural detection and mitigation approaches are strongly recommended for targeted networks since they can compare peacetime with battles and take a wider range of factors into consideration than anomalous thresholds or attack signatures.”

Traffic spoofing and UDP-style attacks were popular in the first half of the year, with an 84% increase in UDP attacks compared to the previous six months. Nexusguard observed several types of UDP attacks in use, one of which can cause “Black Storm” attacks theorised in recent research.