Ramblings of a CyberSecurity Nerd

🧨 When the Backbone Buckles: Cloudflare’s Outage Meets Aisuru’s Mega-DDoS

🚨 Incident Summary

On Tuesday, November 18, 2025, Cloudflare — a backbone provider for roughly one-fifth of the web — suffered a widespread outage. The disruption knocked services like ChatGPT, X (formerly Twitter), and dozens of others offline for users.

In parallel, the Aisuru botnet has been wreaking havoc in recent weeks, including leveraging infrastructure such as Cloudflare’s DNS resolver (1.1.1.1) to amplify or mask its operations. The overlap of these two events highlights a dangerous truth: even the “safe” parts of the internet can become the weapon.

🔍 What Happened With Cloudflare

  • Around 6:40 a.m. ET, the company detected internal degradation. By around 9:42 a.m., many services had recovered.
  • The root cause was a sudden spike in anomalous traffic to one of Cloudflare’s services, which caused widespread network errors.
  • Major platforms reported outages or degraded performance, including OpenAI (ChatGPT), X, and other SaaS platforms.
  • Cloudflare stated that this incident was not caused by a malicious attack, though it is still under investigation.

🧠 What’s Going On With Aisuru and Cloudflare Infrastructure

  • The Aisuru botnet consists of hundreds of thousands of infected IoT devices (routers, IP cameras, DVRs, etc.).
  • It has been seen launching multi-terabit DDoS attacks, including a 15.72 Tbps assault on Microsoft Azure just one day earlier.
  • Aisuru began using Cloudflare’s public DNS resolver (1.1.1.1) to mask its activity and boost domain traffic rankings.
  • Cloudflare confirmed that Aisuru-controlled domains began appearing in its “top domains” public telemetry and has since removed them.

🧩 Why This Matters for Security and Cloud Teams

  • Single-point dependency is a massive risk: If you rely on a backbone provider like Cloudflare, you inherit their failure modes.
  • Trusted infrastructure is not immune: When a botnet uses 1.1.1.1 as a tool, defenders need to rethink their assumptions.
  • Short incidents, wide blast radius: Cloudflare’s outage lasted a few hours, but its reach was massive. The Aisuru DDoS attack lasted under two minutes and still made headlines.
  • Cloud-scale DDoS is not just a myth: The botnet that hit Azure is real, global, and active. If you’re online, you’re in scope.

🛠️ Recommendations for Defense

  • Map your third-party dependencies and ask what happens if any of them go offline for an hour.
  • Deploy alternate DNS resolvers and CDNs where possible to avoid full blackouts.
  • Use automated health checks to divert or degrade traffic gracefully when upstream services fail.
  • Set up alerting for unusual DNS lookups, traffic spikes, or dependency flapping.
  • Run tabletop simulations for provider outages, not just cyberattacks.
  • Share intel with upstream providers and peers when you detect abuse of critical infrastructure.

đź”— Reference Sources

🚨 Final Takeaway

Today’s Cloudflare outage and yesterday’s Aisuru-driven DDoS against Microsoft Azure are a flashing red warning for anyone operating online infrastructure. The backbone cracked in the morning, and the same backbone was used by a global botnet to hit one of the largest cloud providers in the world the day before.

This is reality. If your services depend on cloud infrastructure, DNS, or CDN providers like Cloudflare, then their risk becomes your risk. Build like they will fail — because one day, they might.

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