An application layer attack is a type of cyberattack that targets the application layer (Layer 7) of the OSI model, focusing on exploiting vulnerabilities in web applications, APIs, and software services rather than underlying network infrastructure. These sophisticated attacks manipulate application code flaws, configuration weaknesses, or business logic errors, often disguising malicious activity as legitimate user requests to bypass traditional security defenses.

Unlike network-level attacks, application layer attacks interact directly with applications to exhaust resources, inject malicious data, gain unauthorized access, or exfiltrate sensitive information. Common examples include SQL injection, cross-site scripting (XSS), and HTTP flood attacks. Because they mimic normal traffic patterns, these attacks are particularly difficult to detect, requiring advanced security measures such as web application firewalls, secure coding practices, and behavior-based threat detection to effectively mitigate the risks of data breaches, service disruption, and financial losses.