Lambda

Adversaries may delete AWS Lambda functions to disrupt business operations, remove evidence of their presence, or impede incident response, an action detectable by monitoring for `DeleteFunction` calls in `aws.cloudtrail` logs and correlating with expected change windows.

This brief identifies the critical risk of an AWS Lambda layer's permission policy being modified, typically via the `AddLayerVersionPermission` API, to grant external AWS accounts, AWS Organizations, or the public access, potentially leading to the leakage of proprietary code or secrets and creating a supply-chain vector for attacker-influenced code execution in downstream functions.

Detects the first direct invocation of an AWS Lambda function by a principal within a 14-day period, excluding AWS service invocations, which can indicate adversary lateral movement, credential abuse, or unauthorized data retrieval in AWS environments.

Attackers are abusing stolen AWS execution-role or user credentials to invoke AWS Lambda functions from unusual source networks (ASNs) not previously associated with the legitimate principal, indicating a credential compromise leading to potential unauthorized access or data exfiltration.

Detection of IAM API calls that create or empower IAM users and roles, attach policies, or configure instance profiles when the caller is an assumed role session associated with AWS Lambda, potentially indicating privilege escalation or persistence.

Detection of a Lambda layer being added to an existing AWS Lambda function, potentially indicating malicious activity such as persistence, unauthorized code execution, or data interception by an attacker with the ability to modify function configurations.