Serverless and Function-as-a-Service Threats

Serverless architectures eliminate traditional infrastructure management but introduce unique security challenges. Function code often has broader permissions than necessary because least-privilege policies are complex to craft. Cold start performance pressures might lead to security shortcuts. The event-driven nature makes tracing attacks across multiple functions difficult.

Third-party dependency risks amplify in serverless environments. Functions typically bundle all dependencies, making supply chain attacks particularly effective. Vulnerabilities in dependencies affect all function invocations until patched and redeployed. The ease of function deployment might lead to proliferation of outdated, vulnerable code. Dependency scanning becomes crucial but is often overlooked.

Data injection through event sources represents a common serverless threat. Functions process events from various sources—API Gateway, S3, SQS, SNS—each with different trust levels. Inadequate input validation allows injection attacks. Event source misconfigurations might allow unauthorized event injection. The variety of event sources and formats complicates comprehensive input validation.

Billing attacks target the consumption-based pricing of serverless platforms. Attackers might trigger excessive function invocations to inflate costs. Recursive function calls could create runaway billing. Even failed authentication attempts cost money in serverless architectures. Cost controls and monitoring become security controls in serverless threat models.