ID | Technique | Tactic |
---|---|---|
T1556.006 | Multi-Factor Authentication | Credential Access |
Detection: ASL AWS New MFA Method Registered For User
Description
The following analytic identifies the registration of a new Multi-Factor Authentication (MFA) method for an AWS account, as logged through Amazon Security Lake (ASL). It detects this activity by monitoring the CreateVirtualMFADevice
API operation within ASL logs. This behavior is significant because adversaries who gain unauthorized access to an AWS account may register a new MFA method to maintain persistence. If confirmed malicious, this activity could allow attackers to secure their access, making it harder to detect and remove their presence from the compromised environment.
Search
1`amazon_security_lake` api.operation=CreateVirtualMFADevice
2| fillnull
3| stats count min(_time) as firstTime max(_time) as lastTime by actor.user.uid api.operation api.service.name http_request.user_agent src_endpoint.ip actor.user.account.uid cloud.provider cloud.region
4| rename actor.user.uid as user api.operation as action api.service.name as dest http_request.user_agent as user_agent src_endpoint.ip as src actor.user.account.uid as vendor_account cloud.provider as vendor_product cloud.region as vendor_region
5| `security_content_ctime(firstTime)`
6| `security_content_ctime(lastTime)`
7| `asl_aws_new_mfa_method_registered_for_user_filter`
Data Source
Name | Platform | Sourcetype | Source |
---|---|---|---|
ASL AWS CloudTrail | 'aws:asl' |
'aws_asl' |
Macros Used
Name | Value |
---|---|
amazon_security_lake | sourcetype=aws:asl |
asl_aws_new_mfa_method_registered_for_user_filter | search * |
asl_aws_new_mfa_method_registered_for_user_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 Notable | Yes |
Rule Title | %name% |
Rule Description | %description% |
Notable Event Fields | user, dest |
Creates Risk Event | True |
Implementation
The detection is based on Amazon Security Lake events from Amazon Web Services (AWS), which is a centralized data lake that provides security-related data from AWS services. To use this detection, you must ingest CloudTrail logs from Amazon Security Lake into Splunk. To run this search, ensure that you ingest events using the latest version of Splunk Add-on for Amazon Web Services (https://splunkbase.splunk.com/app/1876) or the Federated Analytics App.
Known False Positives
Newly onboarded users who are registering an MFA method for the first time will also trigger this detection.
Associated Analytic Story
Risk Based Analytics (RBA)
Risk Message:
A new virtual device is added to user $user$
Risk Object | Risk Object Type | Risk Score | Threat Objects |
---|---|---|---|
user | user | 64 | src |
References
Detection Testing
Test Type | Status | Dataset | Source | Sourcetype |
---|---|---|---|---|
Validation | ✅ Passing | N/A | N/A | N/A |
Unit | ✅ Passing | Dataset | aws_asl |
aws:asl |
Integration | ✅ Passing | Dataset | aws_asl |
aws:asl |
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: 10