ID | Technique | Tactic |
---|---|---|
T1078.004 | Cloud Accounts | Defense Evasion |
T1078 | Valid Accounts | Initial Access |
Detection: Abnormally High Number Of Cloud Security Group API Calls
EXPERIMENTAL DETECTION
This detection status is set to experimental. The Splunk Threat Research team has not yet fully tested, simulated, or built comprehensive datasets for this detection. As such, this analytic is not officially supported. If you have any questions or concerns, please reach out to us at research@splunk.com.
Description
The following analytic detects a spike in the number of API calls made to cloud security groups by a user. It leverages data from the Change data model, focusing on successful firewall-related changes. This activity is significant because an abnormal increase in security group API calls can indicate potential malicious activity, such as unauthorized access or configuration changes. If confirmed malicious, this could allow an attacker to manipulate security group settings, potentially exposing sensitive resources or disrupting network security controls.
Search
1
2| tstats count as security_group_api_calls values(All_Changes.command) as command from datamodel=Change where All_Changes.object_category=firewall AND All_Changes.status=success by All_Changes.user _time span=1h
3| `drop_dm_object_name("All_Changes")`
4| eval HourOfDay=strftime(_time, "%H")
5| eval HourOfDay=floor(HourOfDay/4)*4
6| eval DayOfWeek=strftime(_time, "%w")
7| eval isWeekend=if(DayOfWeek >= 1 AND DayOfWeek <= 5, 0, 1)
8| join user HourOfDay isWeekend [ summary cloud_excessive_security_group_api_calls_v1]
9| where cardinality >=16
10| apply cloud_excessive_security_group_api_calls_v1 threshold=0.005
11| rename "IsOutlier(security_group_api_calls)" as isOutlier
12| where isOutlier=1
13| eval expected_upper_threshold = mvindex(split(mvindex(BoundaryRanges, -1), ":"), 0)
14| where security_group_api_calls > expected_upper_threshold
15| eval distance_from_threshold = security_group_api_calls - expected_upper_threshold
16| table _time, user, command, security_group_api_calls, expected_upper_threshold, distance_from_threshold
17| `abnormally_high_number_of_cloud_security_group_api_calls_filter`
Data Source
Name | Platform | Sourcetype | Source | Supported App |
---|---|---|---|---|
AWS CloudTrail | AWS | 'aws:cloudtrail' |
'aws_cloudtrail' |
N/A |
Macros Used
Name | Value |
---|
| abnormally_high_number_of_cloud_security_group_api_calls_filter | search *
|
abnormally_high_number_of_cloud_security_group_api_calls_filter
is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
Annotations
Default Configuration
This detection is configured by default in Splunk Enterprise Security to run with the following settings:
Setting | Value |
---|---|
Disabled | true |
Cron Schedule | 0 * * * * |
Earliest Time | -70m@m |
Latest Time | -10m@m |
Schedule Window | auto |
Creates Risk Event | True |
Implementation
You must be ingesting your cloud infrastructure logs. You also must run the baseline search Baseline Of Cloud Security Group API Calls Per User
to create the probability density function model.
Known False Positives
None.
Associated Analytic Story
Risk Based Analytics (RBA)
Risk Message | Risk Score | Impact | Confidence |
---|---|---|---|
user $user$ has made $api_calls$ api calls related to security groups, violating the dynamic threshold of $expected_upper_threshold$ with the following command $command$. | 15 | 30 | 50 |
Detection Testing
Test Type | Status | Dataset | Source | Sourcetype |
---|---|---|---|---|
Validation | Not Applicable | N/A | N/A | N/A |
Unit | ✅ Passing | Dataset | aws_cloudtrail |
aws:cloudtrail |
Integration | ✅ Passing | Dataset | aws_cloudtrail |
aws:cloudtrail |
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: GitHub | Version: 3