This search looks for AWS CloudTrail events where an instance is started in a particular region in the last one hour and then compares it to a lookup file of previously seen regions where an instance was started
- Type: Anomaly
Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Last Updated: 2018-02-23
- Author: Bhavin Patel, Splunk
- ID: ada0f478-84a8-4641-a3f3-d82362d6fd75
|T1535||Unused/Unsupported Cloud Regions||Defense Evasion|
Kill Chain Phase
- Actions on Objectives
- CIS 12
1 2 3 4 5 6 7 8 9 10 `cloudtrail` earliest=-1h StartInstances | stats earliest(_time) as earliest latest(_time) as latest by awsRegion | inputlookup append=t previously_seen_aws_regions.csv | stats min(earliest) as earliest max(latest) as latest by awsRegion | outputlookup previously_seen_aws_regions.csv | eval regionStatus=if(earliest >= relative_time(now(),"-1d@d"), "Instance Started in a New Region","Previously Seen Region") | `security_content_ctime(earliest)` | `security_content_ctime(latest)` | where regionStatus="Instance Started in a New Region" | `ec2_instance_started_in_previously_unseen_region_filter`
The SPL above uses the following Macros:
Note that ec2_instance_started_in_previously_unseen_region_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
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. Run the “Previously seen AWS Regions” support search only once to create of baseline of previously seen regions. This search is deprecated and have been translated to use the latest Change Datamodel.
Known False Positives
It’s possible that a user has unknowingly started an instance in a new region. Please verify that this activity is legitimate.
Associated Analytic story
source | version: 1