Understanding DDoS

What is a Botnet?

A botnet is a network of infected devices controlled remotely by an attacker. These devices (computers, servers, IoT cameras, routers) are called "zombies" or "bots."

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Device owners often don't know their devices are compromised.

How Botnets Are Built

1. Infection

• Phishing emails with malware
• Exploiting software vulnerabilities
• Brute-forcing weak passwords (especially IoT devices with default credentials)

2. Command & Control (C&C)

• Infected devices connect to attacker's control server
• Attacker issues commands to entire botnet simultaneously

3. Attack Launch

• Thousands or millions of devices attack the target at once
• Appears to come from legitimate sources worldwide

Real-World Example: Bit-and-Piece Attack (Carpet Bombing)

Identified by Nexusguard Research, the bit-and-piece attack (also known as carpet bombing) represents a new breed of stealthy DDoS attacks specifically targeting Communication Service Providers (CSPs) and large networks.

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What Makes It Different:‍

Unlike traditional attacks targeting single IPs, bit-and-piece attacks disperse small pieces of junk traffic across a diverse pool of IP addresses across hundreds of IP prefixes within your network.

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How It Works:

• Attack traffic is mixed with legitimate traffic
• Small amounts sent to IP₁, IP₂, IP₃... IP₂₅₄ (hundreds or thousands of IPs)
• Each individual IP receives traffic below detection thresholds
• Traffic converges toward target IP prefix, forming a massive flow
• Easily exceeds capacity limits of generic mitigation devices

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Why It's Dangerous:

Detection Challenge:

• Legacy flow-aware devices (firewalls, load balancers, IPS, IDS) often fail to detect these stealthy network layer attacks
• No single IP shows massive traffic spike
• Traffic appears distributed and "normal"
• Detection devices themselves can become bottlenecks

Mitigation Challenge:

• Traditional blackholing (blocking specific IPs) is no longer effective
• Can't block hundreds of destination IPs without blocking legitimate services
• Causes high latency at best, or network deadlock at worst
• Requires advanced network behavior analysis (NBA)

Defense Requirements:

• Traffic anomaly detection across entire IP ranges
• Network behavior analysis (not just per-IP monitoring)
• Cloud-based scrubbing with massive capacity
• Real-time traffic visibility and attack analytics

(Source: Nexusguard, "How to Detect and Mitigate Bit-and-Piece DDoS Attack")

Why Botnets Are Hard to Stop

• Global Distribution: Bots spread across countries and networks
• Legitimate-Looking Traffic: Each bot sends normal requests
• Massive Scale: Modern botnets control millions of devices
• Constantly Evolving: New botnet malware variants appear regularly

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