Ensure that Lambda Function execution role policy doesn't have excessive permissions (Contains a wildcard)

Risk Level: High
Cloud Entity: AWS Lambda
CloudGuard Rule ID: D9.AWS.IAM.55
Covered by Spectral: No
Category: Compute

GSL LOGIC

Lambda should not have executionRole.combinedPolicies contain [ relationType!='AssumeRole' and policyDocument.Statement contain [Effect='Allow' and (Action contain [$ regexMatch /\*/] or Action regexMatch /\*/) ]]

REMEDIATION

From Portal

1. Go to 'IAM'
2. In the menu, under 'Access management', choose 'Roles'
3. Select the overly permissive IAM Role
4. Select the relevant policy
5. Redefine its permissions based on the principle of least privilege

From TF
To update an IAM policy, edit the 'Action' argument:

resource "aws_iam_policy" "example_iam_policy" {
	..
	policy = jsonencode({
		..
		Statement = [
		{
			..
			Action = ACTIONS-LIST
			..
		},
		]
	})
}

From Command Line
To update a managed policy, use:

aws iam create-policy-version --policy-arn POLICY-ARN --policy-document POLICY-DOCUMENT

Note: Additional instructions (For example: How to update inline policy) can be found within the references.

References

1. https://docs.aws.amazon.com/lambda/latest/dg/access-control-identity-based.html
2. https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/iam_policy
3. https://docs.aws.amazon.com/IAM/latest/UserGuide/access_policies_manage-edit.html

AWS Lambda

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Compliance Frameworks

• AWS CSA CCM v.4.0.1
• AWS CloudGuard Best Practices
• AWS CloudGuard SOC2 based on AICPA TSC 2017
• AWS HITRUST
• AWS HITRUST v11.0.0
• AWS ISO27001:2022
• AWS ITSG-33
• AWS MITRE ATT&CK Framework v10
• AWS MITRE ATT&CK Framework v11.3
• AWS NIST 800-53 Rev 5
• AWS PCI-DSS 4.0
• AWS Security Risk Management
• CloudGuard AWS All Rules Ruleset