Overview: Denial of Service (DoS)

Quick Definition

A Denial of Service (DoS) attack is a cyberattack designed to make a computer system or network resource unavailable to legitimate users. The attack works by overwhelming the target with a flood of illegitimate requests, consuming available bandwidth, server resources, or network capacity until the system can no longer respond to legitimate traffic.

DoS attacks can target various system components including web servers, network infrastructure, or specific applications. Common methods include flooding targets with connection requests, sending malformed packets that cause systems to crash, or exploiting vulnerabilities that cause resource exhaustion. When multiple compromised computers coordinate such an attack, it becomes a Distributed Denial of Service (DDoS) attack, which is significantly more powerful and harder to defend against.

Organizations typically defend against DoS attacks through rate limiting, traffic filtering, load balancing, and specialized DDoS mitigation services. Cloud-based protection services can absorb large-scale attacks before they reach the target infrastructure. While DoS attacks don't typically steal data, they can cause significant business disruption, financial losses, and reputational damage, making them a serious concern for any organization with an online presence.