Serverless technologies like AWS Lambda dramatically simplify infrastructure management but misconfigurations can expose cloud environments to serious security risks. This guide walks through core concepts, essential setup, and three hands-on exploitation scenarios involving misconfigured Lambda functions.

I. Understanding Key AWS Lambda Concepts

1. What is AWS Lambda?

AWS Lambda is the foundation of many serverless architectures. It allows you to run code without provisioning or managing servers.

Key characteristics:

• Serverless Execution Model: AWS handles infrastructure, scaling, patching, and capacity.
• Event-Driven: Lambda functions can be triggered by S3 uploads, DynamoDB updates, API Gateway calls, and many other AWS services.
• Pay-Per-Use: You are billed only for execution time, measured in milliseconds.
• Multi-language Support: Includes Python, Node.js, Java, Go, C#, and more.

II. Overview of Misconfiguration Scenarios

This guide explores common high-impact Lambda misconfigurations:

1. Cross-Account Lambda Invocation

   (When any AWS user can invoke your function)

2. Lambda RCE via Vulnerable Code

   (Command injection leading to privileged IAM role access)

3. Reverse Shell Inside a Lambda Environment

   (Gaining interactive shell access)

It also covers environment setup and cleanup to avoid unnecessary cloud costs.

III. Exploitation Scenarios

Scenario 1 : Cross-Account Access to a Lambda Function

A Lambda function exposed to arbitrary AWS users can be invoked—or in some cases, its code downloaded—by anyone with AWS credentials.

A. Prerequisites

1. Ensure an AWS CLI profile named securitymaster exists.

   • Verify using:

     aws sts get-caller-identity --profile securitymaster
     

     Purpose: Confirms AWS CLI credentials are valid.