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ec2_instance_modified_with_previously_unseen_user.yml
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ec2_instance_modified_with_previously_unseen_user.yml
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name: EC2 Instance Modified With Previously Unseen User
id: 56f91724-cf3f-4666-84e1-e3712fb41e76
version: 3
date: '2020-07-21'
author: David Dorsey, Splunk
status: deprecated
type: Anomaly
description: This search looks for EC2 instances being modified by users who have
not previously modified them. This search is deprecated and have been translated
to use the latest Change Datamodel.
data_source: []
search: '`cloudtrail` `ec2_modification_api_calls` [search `cloudtrail` `ec2_modification_api_calls`
errorCode=success | stats earliest(_time) as firstTime latest(_time) as lastTime
by userIdentity.arn | rename userIdentity.arn as arn | inputlookup append=t previously_seen_ec2_modifications_by_user
| stats min(firstTime) as firstTime, max(lastTime) as lastTime by arn | outputlookup
previously_seen_ec2_modifications_by_user | eval newUser=if(firstTime >= relative_time(now(),
"-70m@m"), 1, 0) | where newUser=1 | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`
| rename arn as userIdentity.arn | table userIdentity.arn] | spath output=dest responseElements.instancesSet.items{}.instanceId
| spath output=user userIdentity.arn | table _time, user, dest | `ec2_instance_modified_with_previously_unseen_user_filter`'
how_to_implement: You must install the AWS App for Splunk (version 5.1.0 or later)
and Splunk Add-on for AWS (version 4.4.0 or later), then configure your AWS CloudTrail
inputs. This search works best when you run the "Previously Seen EC2 Launches By
User" support search once to create a history of previously seen ARNs. To add or
remove APIs that modify an EC2 instance, edit the macro `ec2_modification_api_calls`.
known_false_positives: It's possible that a new user will start to modify EC2 instances
when they haven't before for any number of reasons. Verify with the user that is
modifying instances that this is the intended behavior.
references: []
tags:
analytic_story:
- Unusual AWS EC2 Modifications
asset_type: AWS Instance
confidence: 50
impact: 50
message: tbd
mitre_attack_id:
- T1078.004
observable:
- name: field
type: Unknown
role:
- Unknown
product:
- Splunk Enterprise
- Splunk Enterprise Security
- Splunk Cloud
required_fields:
- _time
- errorCode
- userIdentity.arn
risk_score: 25.0
security_domain: endpoint