Application layer attack

An application layer attack is a type of cyberattack that targets Layer 7 (the application layer) of the OSI model. Rather than exploiting network infrastructure or protocols, these attacks focus on vulnerabilities in web applications, APIs, and software services — including flaws in application code, configuration settings, or business logic. Because they often mimic legitimate user requests, application layer attacks are particularly difficult to detect with traditional perimeter defenses such as firewalls or intrusion detection systems.

Common examples include SQL injection, cross-site scripting (XSS), and HTTP flood DDoS attacks. The goals of these attacks typically involve unauthorized access, data theft, service disruption through resource exhaustion, or manipulation of application functionality. A successful application layer attack can lead to severe data breaches, financial losses, and reputational damage. Defending against them requires secure coding practices, thorough security testing, web application firewalls (WAFs), and advanced behavioral threat detection.