NikoTak – Tamara Shostak's blog

Just when we think we understand the full scope of denial-of-service attacks, threat actors continue to innovate. As a data scientist working in cybersecurity, I’m particularly intrigued by the emergence of CPDoS (Cache-Poisoned Denial-of-Service) attacks, which represent a sophisticated evolution in how attackers can manipulate the infrastructure we rely on.

What fascinates me about CPDoS is its elegant simplicity combined with devastating effectiveness. Unlike traditional DoS attacks that require massive traffic volumes, CPDoS achieves denial of service by poisoning CDN caches through clever manipulation of HTTP headers. One successful attack can make content unavailable to all subsequent users – a multiplier effect that makes this attack particularly efficient for bad actors.

Let me break down the three variants I’ve observed:

1. HTTP Header Oversize:

• Exploits the disparity between header size limits
• Takes advantage of Apache’s default 8,190-byte limit
• Creates an amplification effect through cache poisoning

1. HTTP Meta Character:

• Leverages sophisticated header manipulation
• Exploits differences in character handling between cache and origin
• Forces error responses that persist in cache

1. HTTP Method Override:

• Manipulates HTTP Standard methods
• Uses unsupported methods like DELETE to trigger errors
• Weaponizes normal HTTP behaviors

What makes these attacks particularly interesting from a security perspective is their exploitation of legitimate infrastructure behaviors rather than obvious vulnerabilities. This is exactly the kind of challenge that modern AI-driven security systems are well-positioned to address.

As we look toward the future of defense against such attacks, I’m excited about how transformer-based models can help us:

• Understand the context of HTTP requests across multiple time scales
• Identify subtle patterns in header manipulation
• Predict and prevent cache poisoning attempts before they succeed

While traditional security solutions struggle with these attacks, I believe we’re entering an era where intelligent, adaptive defense systems can provide robust protection. At Reblaze, we’ve already integrated these protections into our WAF solution, but I see this as just the beginning. The future of security lies in systems that can understand and adapt to evolving threats in real-time.

Want to learn more about how we’re using advanced AI to protect against CPDoS and other emerging threats? Reach out to us at Reblaze, and let’s discuss how we can secure your infrastructure against tomorrow’s attacks.