Unpacking the Triple Threat of Carpet Bomb Attacks: Evasion, Neutralization, and Overload

This Industry Viewpoint was authored by Ashley Stephenson, CTO of Corero Network Security

Nature often provides insightful parallels to our complex digital world. For instance, one might think of a business network connected to the internet as a dynamic beehive where each bee symbolizes a unique IP address of the customer, all tirelessly working to ensure the entire colony remains connected. Much like bees in a hive, these IP addresses constantly relay information in order to communicate vital signals or potential threats. You could think of a conventional DDoS attack as a swarm of wasps attacking a solitary bee or a single IP address. If they succeed, the bee dies but the overall integrity of the hive would remain intact. 

During a carpet bomb DDoS attack, a type of digital assault in which a range of IP addresses is concurrently bombarded with a high volume of malicious data packets, the entire hive of IP addresses may be attacked indiscriminately, with the goal of causing widespread service disruptions, effectively paralyzing the colony.

While carpet bomb attacks are not new per se, recent trends indicate a concerning rise in their frequency and size. Reports of carpet bomb DDoS attacks, while sporadic in the past, appear to be on the rise. According to the recently released 2023 DDoS Threat Intelligence Report, last year witnessed a staggering 300% increase in such attacks compared to the preceding year.

For ISPs, hosting providers, and SaaS providers whose business is dependent on maintaining service uptime and network performance, DDoS carpet bomb attacks represent an existential threat that requires a fresh approach to detection and mitigation.

Deconstructing the Triple Threat of Carpet Bomb Attacks

To mount an effective defense against carpet bomb attacks, a thorough understanding of their operational mechanics is crucial. There are three core strategies employed by threat actors that make these particular attacks especially challenging to detect and mitigate in a timely manner:

1. Evading Detection: Traditional DDoS defense systems are often designed to detect anomalous behavior by applying thresholds that trigger alerts when a surge in traffic to a specific victim IP address is detected. By distributing a high volume of attack traffic across a range of IP addresses, carpet bomb attacks seek to circumvent or confuse these anomalous behavior triggers by lowering traffic levels to each individual IP address below normal detection thresholds. This can make accurate or consistent detection an order of magnitude more difficult.

2. Neutralizing Mitigation: The null route or black hole is a common last-resort defense tool against DDoS attacks, often used when providers or businesses lack other alternatives. It isolates the victim of the attack and discards all their traffic – including legitimate packets – effectively protecting the rest of the network from collateral damage at the cost of serving the attacker’s objective by sacrificing the victim. However, the sophistication of carpet bomb attacks neutralizes this technique’s effectiveness. Unlike traditional attacks that target a single IP address, carpet bomb attacks create numerous proxy victims spread across the targeted IP space by blanketing every IP address within the victim’s subnet (or even all IP addresses associated with the victim’s network). Should a service provider attempt the common defense to null route the attacked IP addresses, it would inadvertently harm valid traffic for all customers within the IP range, thereby causing a virtual shutdown of the service provider’s operations.

3. Overloading Systems: Threat actors also leverage the expanded victim address range of carpet bombing to amplify an attack’s impact by triggering any number of indirect overload scenarios. This is an effective tactic since most conventional DDoS mitigation systems treat each attacked IP address as a distinct victim and consequently struggle to manage and process attack traffic being sent simultaneously to large numbers of IP addresses. Systems that historically have had to deal with only a handful of DDoS victims at the same time, now find themselves trying to manage the detection, mitigation, and reporting of thousands of simultaneous attacks, resulting in potential overloads across many dimensions. The breadth of victim IP address ranges of carpet bomb attacks also presents specific scalability issues for detect-and-redirect DDoS mitigation techniques that normally reroute attacked IP addresses to on-network scrubbing centers or remote cloud-based scrubbing solutions. When an entire service provider’s address space is targeted, these mechanisms may suffer capacity or even billing overload if they attempt to divert all incoming traffic for the provider’s network for scrubbing.

3 Ways to Protect Against Carpet Bombing

Mounting an effective defense against carpet bombing and other emerging DDoS attacks requires a combination of purpose-built technology, proactive network management, and an agile infrastructure. When evaluating a DDoS vendor, you should ensure that any solution possesses the following minimum capabilities:

1. Automated Response: Mitigating DDoS attacks in a manual fashion is typically ineffective in today’s networks with the vast majority of DDoS attacks still coming in under 10 Gbps in size and less than ten minutes in duration. The requirement for scalable automation is even more critical in the case of carpet bomb attacks due to the large number of simultaneous attack targets. That’s why it’s essential to choose an automated DDoS solution that can accurately detect and block attacks within seconds, without requiring any operator intervention. 

2. Carpet Bomb-Aware Detection, Mitigation, and Reporting Tools: As noted above, the large number of target IP addresses associated with carpet bombing confuses traditional detection mechanisms, neutralizes last-resort mitigation systems, and results in multi-dimensional overload scenarios. A modern DDoS mitigation platform must be able to recognize, track, and mitigate attacks that simultaneously target hundreds, if not thousands, of IP addresses in order to protect against the anomalous traffic patterns that characterize a carpet bomb DDoS attack. The same tools should be able to recognize and appropriately report that these patterns indicate a carpet bomb vector is present.

3. Minimize Single Points of Failure or Leakage: By coordinating DDoS detection and mitigation across the entire network edge and all points of presence, the chances of identifying and mitigating carpet bomb DDoS attacks increase significantly. This approach of tracking the attack traffic across a wider area aims to prevent attack leakage at any one point and allow the network to continue functioning even under the challenging conditions of a carpet bomb assault. 

The recent rise of carpet bomb DDoS attacks underscores the ever-evolving ingenuity of threat actors, illustrating their adaptability and drive to exploit DDoS defense vulnerabilities in novel and disruptive ways. Likewise, for hosting and service providers to have a chance at effectively responding to the current surge of carpet bomb attacks or stopping the next wave of DDoS variants, they will need to upgrade their own defensive posture in order to meet the challenges of today as well as the unknown threats of tomorrow.

Ashley Stephenson is the CTO of Corero Network Security, a leading provider of DDoS protection solutions. 

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Categories: Industry Viewpoint · Security