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splunk-security_content/detections/cloud/aws_lambda_updatefunctioncode.yml
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2022-03-03 18:22:29 +00:00

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YAML

name: AWS Lambda UpdateFunctionCode
id: 211b80d3-6340-4345-11ad-212bf3d0d111
version: 1
date: '2022-02-24'
author: Bhavin Patel, Splunk
type: Hunting
datamodel: []
description: This analytic is designed to detect IAM users attempting to update/modify
AWS lambda code via the AWS CLI to gain persistence, futher access into your AWS
environment and to facilitate planting backdoors. In this instance, an attacker
may upload malicious code/binary to a lambda function which will be executed automatically
when the funnction is triggered.
search: '`cloudtrail` eventSource=lambda.amazonaws.com eventName=UpdateFunctionCode* errorCode
= success user_type=IAMUser | stats count min(_time) as firstTime max(_time) as
lastTime values(requestParameters.functionName) as function_updated by src_ip user_arn
user_agent user_type eventName aws_account_id |`aws_lambda_updatefunctioncode_filter`'
how_to_implement: You must install Splunk AWS Add on and enable Cloudtrail logs in
your AWS Environment.
known_false_positives: While this search has no known false positives, it is possible
that an AWS admin or an autorized IAM user has updated the lambda fuction code legitimately.
references:
- http://detectioninthe.cloud/execution/modify_lambda_function_code/
- https://sysdig.com/blog/exploit-mitigate-aws-lambdas-mitre/
tags:
analytic_story:
- Suspicious Cloud User Activities
asset_type: AWS Account
automated_detection_testing: passed
cis20:
- CIS 13
confidence: 90
context:
- Source:Cloud Data
- Outcome:Allowed
- Stage:Execution
dataset:
- https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1204/aws_updatelambdafunctioncode/aws_cloudtrail_events.json
impact: 70
kill_chain_phases:
- Actions on Objectives
message: User $user_arn$ is attempting to update the lambda function code of $function_updated$
from this IP $src_ip$
mitre_attack_id:
- T1204
nist:
- PR.DS
- PR.AC
- DE.CM
observable:
- name: src_ip
type: IP Address
role:
- Attacker
- name: user_arn
type: User
role:
- Attacker
product:
- Splunk Enterprise
- Splunk Enterprise Security
- Splunk Cloud
required_fields:
- _time
- eventName
- userAgent
- errorCode
risk_score: 63
security_domain: cloud