Detection: AWS Bedrock Delete Knowledge Base

Updated Date: 2024-12-05 ID: 8b4e3d62-f743-11ee-9f6e-acde48001123 Author: Bhavin Patel, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic identifies attempts to delete AWS Bedrock Knowledge Bases, which are resources that store and manage domain-specific information for AI models. It monitors AWS CloudTrail logs for DeleteKnowledgeBase API calls. This activity could indicate an adversary attempting to remove knowledge bases after compromising credentials, potentially to disrupt business operations or remove traces of data access. Deleting knowledge bases could impact model performance, remove critical business context, or be part of a larger attack to degrade AI capabilities. If confirmed malicious, this could represent a deliberate attempt to cause service disruption or data loss.

Search

1`cloudtrail` eventSource=bedrock.amazonaws.com eventName=DeleteKnowledgeBase  
2| rename user_name as user  
3| stats count min(_time) as firstTime max(_time) as lastTime values(requestParameters.knowledgeBaseId) as knowledgeBaseIds by src user user_agent vendor_account vendor_product dest signature vendor_region  
4| `security_content_ctime(firstTime)`  
5| `security_content_ctime(lastTime)` 
6| `aws_bedrock_delete_knowledge_base_filter`

Data Source

Name	Platform	Sourcetype	Source
AWS CloudTrail DeleteKnowledgeBase	AWS	`'aws:cloudtrail'`	`'aws_cloudtrail'`

Macros Used

Name	Value
cloudtrail	`sourcetype=aws:cloudtrail`
aws_bedrock_delete_knowledge_base_filter	`search *`

aws_bedrock_delete_knowledge_base_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK

+ Kill Chain Phases

+ NIST

+ CIS

- Threat Actors

ID	Technique	Tactic
T1485	Data Destruction	Impact

Actions on Objectives

DE.CM

CIS 10

LAPSUS$

Lazarus Group

Sandworm Team

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 Notable	Yes
Rule Title	`%name%`
Rule Description	`%description%`
Notable Event Fields	user, dest
Creates Risk Event	True

This configuration file applies to all detections of type TTP. These detections will use Risk Based Alerting and generate Notable Events.

Implementation

The Splunk AWS Add-on is required to utilize this data. The search requires AWS CloudTrail logs with Bedrock service events enabled. You must install and configure the AWS App for Splunk (version 6.0.0 or later) and Splunk Add-on for AWS (version 5.1.0 or later) to collect CloudTrail logs from AWS. Ensure the CloudTrail is capturing Bedrock Knowledge Base management events.

Known False Positives

Legitimate administrators may delete Knowledge Bases as part of normal operations, such as when replacing outdated knowledge bases, removing test resources, or consolidating information. Consider implementing an allowlist for expected administrators who regularly manage Knowledge Base configurations.

Associated Analytic Story

AWS Bedrock Security

Risk Based Analytics (RBA)

Risk Message:

User $user$ deleted AWS Bedrock Knowledge Base $knowledgeBaseIds$ from $src$

Risk Object	Risk Object Type	Risk Score	Threat Objects
user	user	70	src

References

Detection Testing

Test Type	Status	Dataset	Source	Sourcetype
Validation	✅ Passing	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: 1