AWS Lambda Function Created or Updated

[metadata]
bypass_bbr_timing = true
creation_date = "2024/04/20"
integration = ["aws"]
maturity = "production"
updated_date = "2024/09/01"

[rule]
author = ["Elastic"]
building_block_type = "default"
description = """
Identifies when an AWS Lambda function is created or updated. AWS Lambda lets you run code without provisioning or
managing servers. Adversaries can create or update Lambda functions to execute malicious code, exfiltrate data, or
escalate privileges. This is a [building block
rule](https://www.elastic.co/guide/en/security/current/building-block-rule.html) that does not generate alerts, but
signals when a Lambda function is created or updated that matches the rule's conditions. To generate alerts, create a
rule that uses this signal as a building block.
"""
false_positives = [
    """
    Legitimate changes to Lambda functions can trigger this signal. Ensure that the changes are authorized and align
    with your organization's policies.
    """,
]
from = "now-60m"
index = ["filebeat-*", "logs-aws.cloudtrail-*"]
interval = "10m"
language = "kuery"
license = "Elastic License v2"
name = "AWS Lambda Function Created or Updated"
references = [
    "https://mattslifebytes.com/2023/04/14/from-rebuilds-to-reloads-hacking-aws-lambda-to-enable-instant-code-updates/",
    "https://stratus-red-team.cloud/attack-techniques/AWS/aws.persistence.lambda-overwrite-code/",
    "https://docs.aws.amazon.com/lambda/latest/api/API_UpdateFunctionCode.html",
]
risk_score = 21
rule_id = "1251b98a-ff45-11ee-89a1-f661ea17fbce"
severity = "low"
tags = [
    "Domain: Cloud",
    "Data Source: AWS",
    "Data Source: Amazon Web Services",
    "Data Source: AWS Lambda",
    "Use Case: Asset Visibility",
    "Tactic: Execution",
    "Rule Type: BBR"
]
timestamp_override = "event.ingested"
type = "query"

query = '''
event.dataset: "aws.cloudtrail"
    and event.provider: "lambda.amazonaws.com"
    and event.outcome: "success"
    and event.action: (CreateFunction* or UpdateFunctionCode*)
'''


[[rule.threat]]
framework = "MITRE ATT&CK"
[[rule.threat.technique]]
id = "T1648"
name = "Serverless Execution"
reference = "https://attack.mitre.org/techniques/T1648/"


[rule.threat.tactic]
id = "TA0002"
name = "Execution"
reference = "https://attack.mitre.org/tactics/TA0002/"