Ensure that Lambda Function resource-based policy doesn't have excessive permissions (Contains a wildcard)

Risk Level: High
Cloud Entity: AWS Lambda
CloudGuard Rule ID: D9.AWS.IAM.104
Covered by Spectral: No
Category: Compute

GSL LOGIC

Lambda should not have resourcePolicy.Statement contain [ Effect='Allow' and (Action contain [$ regexMatch /\*/] or Action regexMatch /\*/) ]

REMEDIATION

From Portal

1. Go to 'Lambda' dashboard
2. In the left menu, select 'Functions'
3. Select the relevant Lambda Function
4. Under 'Configurations', go to 'Permissions'
5. Under 'Resource-based policy statements', select the relevant statement
6. Edit the statement according to the principle of least privilege

From TF
To edit a resource-based policy, edit the 'action' attribute within 'aws_lambda_permission' block:

resource "aws_lambda_permission" "lambda_permission_example" {
	..
	action = ACTION
	..
}

From Command Line
To remove a resource-based policy statement from a Lambda Function, run:

aws lambda remove-permission --function-name FUNCTION-NAME --statement-id STATEMENT-ID

To apply a resource-based policy statement to a Lambda Function, run:

aws lambda add-permission --function-name FUNCTION-NAME--action ACTION --statement-id STATEMENT-ID --principal PRINCIPAL

References

1. https://docs.aws.amazon.com/lambda/latest/dg/access-control-resource-based.html
2. https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/lambda_permission
3. https://awscli.amazonaws.com/v2/documentation/api/latest/reference/lambda/remove-permission.html
4. https://awscli.amazonaws.com/v2/documentation/api/latest/reference/lambda/add-permission.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 v11.0.0
• AWS PCI-DSS 4.0
• AWS Security Risk Management
• CloudGuard AWS All Rules Ruleset