Try in Splunk Security Cloud

Description

This search looks at cloud-infrastructure events where an instance is created in any region within the last hour and then compares it to a lookup file of previously seen regions where instances have been created.

Annotations

ATT&CK
ID Technique Tactic
T1535 Unused/Unsupported Cloud Regions Defense Evasion
Kill Chain Phase
  • Actions on Objectives
NIST
  • DE.DP
  • DE.AE
CIS20
  • CIS 12
CVE 
1
2
3
4
5
6
7
8
9
10
11

| tstats earliest(_time) as firstTime latest(_time) as lastTime values(All_Changes.object_id) as dest, count from datamodel=Change where All_Changes.action=created by All_Changes.vendor_region, All_Changes.user 
| `drop_dm_object_name("All_Changes")` 
| lookup previously_seen_cloud_regions vendor_region as vendor_region OUTPUTNEW firstTimeSeen, enough_data 
| eventstats max(enough_data) as enough_data 
| where enough_data=1 
| eval firstTimeSeenRegion=min(firstTimeSeen) 
| where isnull(firstTimeSeenRegion) OR firstTimeSeenRegion > relative_time(now(), "-24h@h") 
| table firstTime, user, dest, count , vendor_region 
| `security_content_ctime(firstTime)` 
| `cloud_compute_instance_created_in_previously_unused_region_filter`

Macros

The SPL above uses the following Macros:

Note that cloud_compute_instance_created_in_previously_unused_region_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Lookups

The SPL above uses the following Lookups:

Required field

  • _time
  • All_Changes.object_id
  • All_Changes.action
  • All_Changes.vendor_region
  • All_Changes.user

How To Implement

You must be ingesting your cloud infrastructure logs from your cloud provider. You should run the baseline search Previously Seen Cloud Regions - Initial to build the initial table of images observed and times. You must also enable the second baseline search Previously Seen Cloud Regions - Update to keep this table up to date and to age out old data. You can also provide additional filtering for this search by customizing the cloud_compute_instance_created_in_previously_unused_region_filter macro.

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

RBA

Risk Score Impact Confidence Message
42.0 70 60 User $user$ is creating an instance $dest$ in a new region for the first time

Reference

Test Dataset

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

source | version: 1