printer friendly version

DDoS attacks demand different defence strategies

Despite the fact that firewalls, IPS and load balancers are some of the least effective mitigation measures against distributed denial of service (DDoS) attacks, they remain at the top of the list of security measures that organisations have said they plan to employ against DDoS attacks.

This was a noteworthy finding from the annual 2018 NETSCOUT Arbor Worldwide Infrastructure Security Report (WISR), the company’s annual survey of security professionals in both the service provider and enterprise segments. The 13th annual report was released earlier this year.

Bryan Hamman.

Bryan Hamman, territory manager for sub-Saharan Africa at NETSCOUT Arbor, which specialises in advanced DDoS protection solutions, explains, “This was a discouraging finding when the findings of the report were analysed. Quite simply, DDoS attacks are a different kind of data breach, with the motive behind the attack embedded in the actual name: denial of service.

“The 2018 WISR found that among service providers, firewalls were the second most reported DDoS mitigation option, while on the enterprise side, they were the first choice of 82% of respondents. In essence, some of the most popular DDoS mitigation measures are actually the least effective. This is outlined by the fact that almost half (48%) of datacentre respondents experienced firewall, IDS/IPS device and load balancer failure contributing to an outage during a DDoS attack.”

Hamman explains that because DDoS attacks and data breaches are so different in nature, conventional security infrastructure components used to combat breaches are relatively ineffective at preventing this type of incident. “Security products such as perimeter firewalls and intrusion detection/preventions systems (IDI/IPS) certainly have their place in a layered defence strategy, as they protect data confidentiality and integrity. However, they fail to address network availability, which is the fundamental issue in DDoS attacks.”

The 2018 WISR uncovered a significant increase in DDoS attacks targeting infrastructure during 2017. The report noted that among enterprise respondents, 61% had experienced compromises on network infrastructure, and 52% had firewalls or IPS devices fail or contribute to an outage during a DDoS attack. Attacks on infrastructure are less prevalent among service providers, whose customers are still the primary target of DDoS attacks. Nonetheless, 10% of attacks on service providers targeted network infrastructure and another 15% targeted service infrastructure.

The report further noted that infrastructure components are particularly vulnerable to TCP State Exhaustion attacks, which attempt to consume the connection state tables (session records) used by load balancers, firewalls, IPS and application servers to identify legitimate packet traffic. Such attacks can take down even high-capacity devices capable of maintaining state on millions of connections. The 2018 WISR clarified that TCP State Exhaustion attacks accounted for nearly 12% of all attacks reported during the period under review.

“Because the aim of a DDoS attack is to prevent the delivery of online services that people depend on, top targets logically include financial institutions, gaming and e-commerce websites, as well as cloud service providers that host sites or service applications for business customers. Ensuring that your network infrastructure is protected from DDoS attacks means re-thinking your strategy, and realising that this different kind of occurrence requires a different kind of approach.

“Best practice to protect your infrastructure, as recommended by NETSCOUT Arbor, is generally regarded as being a hybrid solution that combines on-premise defences with cloud-based mitigation capabilities. A dedicated on-premise DDoS appliance deployed in front of infrastructure components will protect them from attacks and enable them to do their job unimpeded,” concludes Hamman.

Share this article:

Further reading: