What is a Botnet?

How Botnets Work

Botnets operate through a simple but powerful model. Attackers infect devices with malware that turns them into "bots" or "zombies." Each infected device connects to a command-and-control (C&C) server controlled by the attacker. Fraudlogix IP Blocklist blocks known botnet traffic sources from accessing your infrastructure. The C&C server sends instructions to all infected devices simultaneously, coordinating their actions.

Think of it like a puppet master controlling thousands of puppets at once. The attacker sends one command and hundreds of thousands of infected devices execute it simultaneously. This amplification gives attackers massive scale without needing massive infrastructure.

Most device owners have no idea their machine is part of a botnet. The malware runs quietly in the background, consuming minimal resources. Computers might run slightly slower or use more bandwidth, but these symptoms are subtle enough that most people don't notice.

Infection Methods

Devices join botnets through various infection vectors. Phishing emails deliver malicious attachments or links. Malicious downloads disguise malware as legitimate software. Exploits target unpatched software vulnerabilities. Malicious ads on compromised websites deliver drive-by downloads. Once one device on a network gets infected, the malware often spreads laterally to other vulnerable systems.

IoT devices have become prime botnet targets because they typically have weak security, rarely get updated, and run 24/7. Security cameras, routers, DVRs, and smart home devices often ship with default passwords and known vulnerabilities. Botnets like Mirai specifically target these devices, creating armies of infected IoT equipment.

Command and Control

Botnet operators use different C&C architectures to maintain control. Centralized models use dedicated servers that all bots connect to. This is efficient but creates a single point of failure. Take down the C&C server and the botnet dies.

Peer-to-peer botnets distribute control across infected devices themselves. Each bot can relay commands to others, making the network more resilient. Law enforcement can't kill it by taking down one server.

Some modern botnets use legitimate platforms like social media or cloud services for C&C communication. Commands get posted to Twitter or stored in public cloud buckets. This makes detection harder since the traffic looks like normal use of legitimate services.

What Botnets Do

Ad Fraud

Botnets generate massive amounts of fake ad traffic. Infected devices click on ads, view impressions, watch videos, and visit websites to inflate metrics. This traffic looks more legitimate than datacenter bots because it comes from real residential IPs and actual consumer devices.

Sophisticated ad fraud botnets rotate through different sites and behaviors to avoid detection. They might watch 30 seconds of video ads, click through to landing pages, even add items to shopping carts. The goal is mimicking real user behavior while generating revenue from fake engagement.

DDoS Attacks

Distributed Denial of Service attacks overwhelm targets with traffic. Botnets with hundreds of thousands of infected devices can generate enormous amounts of requests. They flood servers, saturate bandwidth, or exhaust computing resources until legitimate users can't access services.

DDoS attacks serve different purposes. Some are extortion attempts demanding payment to stop. Others are competitive attacks taking down rivals. Political hacktivists use DDoS to silence opposing voices. Whatever the motivation, botnets provide the scale needed to take down even large targets.

Spam and Phishing

Botnets send billions of spam emails daily. By distributing sending across thousands of infected machines, attackers avoid email server rate limits and blocklists. Each bot sends a small number of messages, making individual devices harder to flag.

These emails deliver phishing attacks, malware, and scams. The botnet operators either run these campaigns themselves or rent their botnet to other criminals. Spam-as-a-service lets anyone pay to blast out messages through someone else's infected device network.

Credential Stuffing

Botnets test stolen username/password combinations across multiple sites through credential stuffing attacks. By distributing attempts across many devices and IPs, they avoid rate limiting and account lockouts. What looks like a few login attempts from each IP is actually millions of attempts coordinated across the botnet.

Cryptomining

Some botnets mine cryptocurrency using infected devices' processing power. This generates revenue for attackers while consuming victims' electricity and degrading device performance. Cryptomining botnets prioritize staying undetected since they profit from long-term access rather than quick attacks.

How to Detect Botnet Traffic

Botnet traffic shows distinctive patterns that help identify it.

Coordinated Activity

Multiple IPs showing identical or near-identical behavior is a key indicator. Same user agents, same browsing paths, same timing patterns across many devices suggests coordination. Real users show natural variation. Bots show suspicious uniformity.

Geographic Anomalies

Traffic patterns that don't match expected geography signal botnets. A campaign targeting US audiences shouldn't see massive traffic from specific regions known for botnet hosting. Unusual concentrations of activity from unexpected locations warrant investigation.

Known Botnet Infrastructure

IP reputation databases track known botnet IPs and C&C servers. Traffic from these sources is almost always malicious. Pre-Bid IP Blocklists maintain updated lists of identified botnet infrastructure, blocking it before it even reaches your systems.

Behavioral Anomalies

Bots often show patterns that humans don't. Perfect mouse movements in straight lines. No random pauses or errors. Consistent timing between actions. Accessing content in illogical sequences. IP Risk Score evaluates these behavioral signals in real-time to identify suspicious patterns.

Volume Spikes

Sudden traffic increases from specific IP ranges or networks can indicate botnet activity. Botnets often ramp up quickly when activated for campaigns. These volume anomalies combined with other indicators help pinpoint coordinated attacks.

How to Block Botnet Traffic

1. IP-Based Blocking

Block known botnet IPs before they reach your infrastructure. Fraudlogix Pre-Bid IP Blocklist provides continuously updated lists of identified botnet nodes, data centers, and malicious infrastructure. Pre-bid filtering stops botnet traffic at the network edge, reducing server load and protecting campaigns.

2. Real-Time Risk Assessment

Evaluate each connection's risk level based on IP reputation, geographic source, network type, and historical behavior. IP Risk Score provides instant risk analysis for every IP, letting you block high-risk sources while allowing legitimate traffic through.

3. Rate Limiting

Limit how many requests any single IP or user can make in a given timeframe. Botnets often generate high volumes of requests quickly. Rate limiting throttles suspicious sources without blocking them entirely, buying time for further analysis.

4. Behavioral Analysis

Monitor for patterns that indicate automated behavior. Consistent timing, perfect mouse movements, and unnatural navigation sequences suggest bots. Flag and challenge suspicious activity with CAPTCHAs or additional verification.

5. Device Fingerprinting

Track device characteristics using device fingerprinting to identify suspicious patterns. Multiple accounts from the same device or device characteristics inconsistent with claimed attributes suggest botnet activity. Fingerprinting helps detect when one infected machine generates many fake identities.

6. Network Analysis

Monitor traffic patterns for coordinated attacks. Sudden spikes from specific ASNs, unusual geographic concentrations, or synchronized activity across multiple IPs indicate botnet campaigns. Network-level analysis catches coordinated attacks that individual IP checks might miss.

Frequently Asked Questions