| name | detecting-serverless-function-injection |
| description | Detects and prevents code injection attacks targeting serverless functions (AWS Lambda, Azure Functions, Google Cloud Functions) through event source poisoning, malicious layer injection, runtime command execution, and IAM privilege escalation via function modification. The analyst combines static analysis of function code, CloudTrail event correlation, runtime behavior monitoring, and IAM policy auditing to identify injection vectors across the expanded serverless attack surface including API Gateway, S3, SQS, DynamoDB Streams, and CloudWatch event triggers. Activates for requests involving Lambda security assessment, serverless injection detection, function event poisoning analysis, or serverless privilege escalation investigation.
|
| domain | cybersecurity |
| subdomain | cloud-security |
| tags | ["serverless-security","Lambda-injection","event-source-poisoning","OWASP-serverless","IAM-escalation","CloudTrail"] |
| version | 1.0.0 |
| author | mukul975 |
| license | Apache-2.0 |
| nist_csf | ["PR.IR-01","ID.AM-08","GV.SC-06","DE.CM-01"] |
Detecting Serverless Function Injection
When to Use
- Auditing Lambda/Cloud Functions for code injection vulnerabilities where unsanitized event data flows into dangerous runtime functions (
eval, exec, child_process.exec, os.system)
- Investigating incidents where an attacker modified function code or layers to establish persistence or exfiltrate data from the serverless environment
- Detecting privilege escalation paths where an adversary with
lambda:UpdateFunctionCode and iam:PassRole can assume higher-privilege execution roles
- Analyzing event source poisoning attacks where malicious payloads are injected through S3 object uploads, SQS messages, DynamoDB stream records, or API Gateway requests that trigger function execution
- Building detection rules for SOC teams monitoring serverless workloads for unauthorized function modifications, layer additions, and suspicious invocation patterns
Do not use for load testing or denial-of-service simulation against serverless functions, for testing against production functions processing live customer data without explicit authorization, or for modifying IAM policies in shared accounts without change management approval.
Prerequisites
- AWS account access with read permissions for Lambda, CloudTrail, IAM, CloudWatch Logs, and EventBridge
- AWS CLI v2 configured with appropriate credentials and region
- CloudTrail enabled with Data Events for Lambda (captures
Invoke events) and Management Events (captures UpdateFunctionCode, UpdateFunctionConfiguration, CreateFunction)
- Python 3.9+ with
boto3, bandit (Python SAST), and semgrep for static analysis
- Access to function source code or deployment packages for static analysis
- CloudWatch Logs Insights access for querying Lambda execution logs
Workflow
Step 1: Enumerate the Serverless Attack Surface
Map all Lambda functions and their event source triggers to understand injection entry points:
- List all Lambda functions and their configurations:
aws lambda list-functions --query 'Functions[*].[FunctionName,Runtime,Role,Handler,Layers]' --output table
- Map event source mappings: Each event source mapping is a potential injection entry point where untrusted data enters the function:
