Detection: Detect Spike in AWS API Activity

Description

This search will detect users creating spikes of API activity in your AWS environment. It will also update the cache file that factors in the latest data. This search is deprecated and have been translated to use the latest Change Datamodel.

Search

 1`cloudtrail` eventType=AwsApiCall [search `cloudtrail` eventType=AwsApiCall 
 2| spath output=arn path=userIdentity.arn 
 3| stats count as apiCalls by arn 
 4| inputlookup api_call_by_user_baseline append=t 
 5| fields - latestCount 
 6| stats values(*) as * by arn 
 7| rename apiCalls as latestCount 
 8| eval newAvgApiCalls=avgApiCalls + (latestCount-avgApiCalls)/720 
 9| eval newStdevApiCalls=sqrt(((pow(stdevApiCalls, 2)*719 + (latestCount-newAvgApiCalls)*(latestCount-avgApiCalls))/720)) 
10| eval avgApiCalls=coalesce(newAvgApiCalls, avgApiCalls), stdevApiCalls=coalesce(newStdevApiCalls, stdevApiCalls), numDataPoints=if(isnull(latestCount), numDataPoints, numDataPoints+1) 
11| table arn, latestCount, numDataPoints, avgApiCalls, stdevApiCalls 
12| outputlookup api_call_by_user_baseline 
13| eval dataPointThreshold = 15, deviationThreshold = 3 
14| eval isSpike=if((latestCount > avgApiCalls+deviationThreshold*stdevApiCalls) AND numDataPoints > dataPointThreshold, 1, 0) 
15| where isSpike=1 
16| rename arn as userIdentity.arn 
17| table userIdentity.arn] 
18| spath output=user userIdentity.arn 
19| stats values(eventName) as eventName, count as numberOfApiCalls, dc(eventName) as uniqueApisCalled by user 
20| `detect_spike_in_aws_api_activity_filter`

Data Source

Macros Used

Annotations

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Implementation

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. You can modify dataPointThreshold and deviationThreshold to better fit your environment. The dataPointThreshold variable is the minimum number of data points required to have a statistically significant amount of data to determine. The deviationThreshold variable is the number of standard deviations away from the mean that the value must be to be considered a spike. This search produces fields (eventName,numberOfApiCalls,uniqueApisCalled) that are not yet supported by ES Incident Review and therefore cannot be viewed when a notable event is raised. These fields contribute additional context to the notable. To see the additional metadata, add the following fields, if not already present, to Incident Review - Event Attributes (Configure > Incident Management > Incident Review Settings > Add New Entry):

• Label: AWS Event Name, Field: eventName
• Label: Number of API Calls, Field: numberOfApiCalls
• Label: Unique API Calls, Field: uniqueApisCalled Detailed documentation on how to create a new field within Incident Review may be found here: https://docs.splunk.com/Documentation/ES/5.3.0/Admin/Customizenotables#Add_a_field_to_the_notable_event_details

Known False Positives

None.

Associated Analytic Story

• AWS User Monitoring

Risk Based Analytics (RBA)

Detection Testing

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