Serverless computing promises reduced operational overhead by eliminating the need to manage servers, patching, and capacity planning. Functions execute on demand, scale automatically, and charge only for actual usage. These benefits have driven rapid adoption across organisations of all sizes. However, serverless does not mean security-free, and the shift in responsibility boundaries catches many teams off guard.

The shared responsibility model for serverless shifts more infrastructure security to the cloud provider while leaving application security, configuration, and access management squarely with the customer. Developers who assume the provider handles all security concerns create functions that expose data, execute with excessive permissions, and accept untrusted input without validation.

Overly permissive IAM roles attached to serverless functions represent one of the most common and dangerous misconfigurations. Developers often assign broad permissions during development to avoid access denied errors and never tighten them before production deployment. A function that only needs to read from a single S3 bucket should not have permissions to access every resource in the account.

Event injection attacks target the various triggers that invoke serverless functions. HTTP requests, message queues, database changes, and file uploads all serve as potential input vectors. Functions that process these events without proper validation expose themselves to injection attacks, data manipulation, and command execution, precisely the same vulnerability categories that affect traditional applications.

Secrets management in serverless environments requires careful handling. Environment variables, while convenient, often store API keys, database credentials, and encryption keys in plaintext accessible to anyone with function configuration access. Dedicated secrets management services that encrypt credentials and control access provide substantially better protection for sensitive configuration data.

Expert Commentary

William Fieldhouse | Director of Aardwolf Security Ltd

“Serverless computing shifts infrastructure management to the provider, but it does not shift security responsibility for the code, configurations, and permissions your functions use. We find excessive IAM permissions, hardcoded secrets, and missing input validation in serverless deployments with concerning frequency. The abstraction layer hides risk rather than eliminating it.”

Cold start behaviour and execution time limits introduce unique security considerations. Functions that execute slowly during cold starts may time out before completing security checks. Error handling paths triggered by timeouts or resource limits may bypass security controls that execute during normal operation. Testing these edge cases reveals vulnerabilities that standard functional testing misses.

Regular AWS penetration testing that covers your serverless architecture examines function permissions, trigger configurations, data handling, and integration security across your Lambda deployment. Professional testers identify privilege escalation paths, data exposure risks, and trust boundary weaknesses specific to serverless environments.

Similarly, Azure penetration testing focused on your Azure Functions deployment evaluates how your serverless workloads interact with other Azure services, whether managed identities are configured securely, and whether function bindings expose unintended access paths to storage accounts, databases, or service bus queues.

Monitoring and logging for serverless functions require adaptation from traditional approaches. Standard infrastructure monitoring does not apply when there are no servers to monitor. Function-level logging, distributed tracing across invocation chains, and anomaly detection tailored to event-driven architectures provide the visibility that serverless security demands.

Serverless computing is here to stay, and its security challenges are manageable with the right approach. Teams that treat serverless functions with the same security discipline they apply to traditional applications, including input validation, least privilege, secrets management, and regular testing, build serverless architectures that deliver on the promise of reduced overhead without introducing unacceptable risk.