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IoT Botnets and DDoS: Why Your Smart Devices Are Attacking the Internet

C

Ceren Yildiz

Security Researcher

May 22, 20248 min read

Billions of IoT devices run embedded Linux with default credentials, no auto-update, and permanent internet exposure. They're the raw material of modern DDoS botnets.

The security model of consumer IoT is fundamentally broken. Manufacturers ship devices with default credentials, ship firmware with known vulnerabilities, provide no reliable update mechanism, and design for easy setup — not security. The result is a global population of billions of always-on, always-connected devices that attackers can recruit into botnets within minutes of finding them.

How Devices Get Recruited

  • Default credential scanning: attackers use masscan or zmap to find devices with open Telnet/SSH.
  • Exploit scanning: post-Mirai botnets use N-day CVEs — known vulnerabilities in specific firmware versions.
  • Malware dropping: once in, a small binary is downloaded and the device is registered with a C2 server.
  • Silent persistence: the device continues operating normally — the owner never knows.

Attack Capabilities of Modern IoT Botnets

  • Multi-vector support: Mirai-descendants can run SYN, ACK, UDP, HTTP flood, and GRE tunneled attacks on command.
  • Hundreds of thousands of bots at 100Mbps each = tens of terabits total.
  • Geographic distribution makes source-based blocking ineffective.
  • Bot churn: infected devices are rebooted (clearing malware) constantly, so botnets cycle nodes continuously.

What IoT Owners Can Do

  • Change default credentials on every device immediately.
  • Enable automatic firmware updates where supported.
  • Put IoT devices on a separate VLAN with no direct internet access.
  • If your router's admin panel is exposed to WAN — close it.
C

Ceren Yildiz

Security Researcher at Akarguard

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