AWS Lambda Function Policy Updated to Allow Public Invocation

Description

Identifies when an AWS Lambda function policy is updated to allow public invocation. This rule detects use of the AddPermission API where the Principal is set to "*", enabling any AWS account to invoke the function. Adversaries may abuse this configuration to establish persistence, create a covert execution path, or operate a function as an unauthenticated backdoor. Public invocation is rarely required outside very specific workloads and should be considered high-risk when performed unexpectedly.

Detection logic

Its licence does not clear it for publishing here

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Detection requirements

Platform: IaaS Linux macOS Office Suite SaaS Windows
The rule states no platform. This is derived from the 2 ATT&CK techniques it maps to.
Log source category: event_index

Known benign triggers

Some organizations may legitimately expose Lambda functions for cross-account or anonymous invocation (e.g., custom public APIs, integrations, or legacy architectures). Validate whether the function owner explicitly intended to make the function publicly invokable. Routine CI/CD deployments or IaC templates may also temporarily set permissive policies; confirm this is expected behavior before treating it as suspicious.

References

Links the source published beside this detection. Reference is the link the source wrote, unmodified. Class is decided by this catalogue from the host and path, not stated by the source. Cited by counts published detections citing the same resource, including this one, and the sources beneath it count the repositories this catalogue ingests, which is not the same as independent research.
Reference	Class	Cited by
cloud.hacktricks.xyz/pentesting-cloud/aws-security/aws-persistence/aws-lambda-persistence	Unclassified	Only this detection cites it
docs.aws.amazon.com/lambda/latest/api/API_AddPermission.html	Product documentation	2
stratus-red-team.cloud/attack-techniques/AWS/aws.persistence.lambda-backdoor-function/	Unclassified	Only this detection cites it

Detection rules

AWS Lambda Function Policy Updated to Allow Public Invocation

Description

Detection logic

Detection requirements

Known benign triggers

MITRE ATT&CK mappings

References

From the source

Licence

Authorship

Detection rules