aws-lambda-exctn-roles

name	aws-lambda-exctn-roles
description	Securing AWS Lambda execution roles by implementing least-privilege IAM policies, applying permission boundaries, restricting resource-based policies, using IAM Access Analyzer to validate permissions, and enforcing role scoping through SCPs.
domain	cybersecurity
subdomain	cloud-security
tags	["cloud-security","aws","lambda","iam","least-privilege","execution-roles"]
version	1.0
author	mahipal
license	Apache-2.0
nist_csf	["PR.IR-01","ID.AM-08","GV.SC-06","DE.CM-01"]

Securing AWS Lambda Execution Roles

When to Use

• When deploying new Lambda functions and defining their IAM execution roles
• When remediating overly permissive Lambda roles discovered during security audits
• When implementing least-privilege access patterns for serverless architectures
• When building reusable IAM templates for Lambda functions across teams
• When Security Hub or Prowler reports Lambda functions with excessive permissions

Do not use for securing Lambda function invocation (use resource-based policies and API Gateway authorizers), for Lambda code security (use SAST tools), or for Lambda network security (use VPC configuration and security groups).

Prerequisites

• IAM permissions for policy creation, role modification, and Access Analyzer operations
• AWS IAM Access Analyzer enabled in the account
• CloudTrail data events enabled for Lambda to capture actual API usage
• Existing Lambda functions to audit and scope permissions for
• Understanding of each function's required AWS service interactions

Workflow

Step 1: Audit Current Lambda Execution Role Permissions

Enumerate all Lambda functions and their associated IAM roles to identify over-privileged functions.

# List all Lambda functions with their execution roles
aws lambda list-functions \
  --query 'Functions[*].[FunctionName,Role]' --output table

# For each function, analyze attached policies
for func in $(aws lambda list-functions --query 'Functions[*].FunctionName' --output text); do
  role_arn=$(aws lambda get-function-configuration --function-name "$func" --query 'Role' --output text)
  role_name=$(echo "$role_arn" | awk -F'/' '{print $NF}')
  echo "=== $func -> $role_name ==="

  # Check for AWS managed policies (often too broad)
  aws iam list-attached-role-policies --role-name "" \
    --query  --output table

  
   policy  $(aws iam list-role-policies --role-name  --query  --output text); 
     
    aws iam get-role-policy --role-name  --policy-name  \
      --query  --output json