THIS IS A EXPERIMENTAL DETECTION
This detection has been marked experimental by the Splunk Threat Research team. This means we have not been able to test, simulate, or build datasets for this detection. Use at your own risk. This analytic is NOT supported.
The following analytic identifies an attempt to disable multi-factor authentication for an AWS IAM user. An adversary who has obtained access to an AWS tenant may disable multi-factor authentication as a way to plant a backdoor and maintain persistence using a valid account. This way the attackers can keep persistance in the environment without adding new users.
- Type: TTP
Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Last Updated: 2023-06-02
- Author: Patrick Bareiss, Splunk
- ID: 4d2df5e0-1092-4817-88a8-79c7fa054668
|T1586||Compromise Accounts||Resource Development|
|T1586.003||Cloud Accounts||Resource Development|
|T1621||Multi-Factor Authentication Request Generation||Credential Access|
|T1556||Modify Authentication Process||Credential Access, Defense Evasion, Persistence|
|T1556.006||Multi-Factor Authentication||Credential Access, Defense Evasion, Persistence|
Kill Chain Phase
- CIS 10
1 2 3 4 5 `amazon_security_lake` (api.operation=DeleteVirtualMFADevice OR api.operation=DeactivateMFADevice) | stats count min(_time) as firstTime max(_time) as lastTime by api.operation api.service.name identity.user.account_uid identity.user.credential_uid identity.user.name identity.user.type identity.user.uid identity.user.uuid http_request.user_agent src_endpoint.ip cloud.region | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `asl_aws_multi_factor_authentication_disabled_filter`
The SPL above uses the following Macros:
asl_aws_multi-factor_authentication_disabled_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
List of fields required to use this analytic.
How To Implement
You must install Splunk Add-On for AWS Version v7.0.0 (https://splunkbase.splunk.com/app/1876) that includes includes a merge of all the capabilities of the Splunk Add-on for Amazon Security Lake. This search works with Amazon Security Lake logs which are parsed in the Open Cybersecurity Schema Framework (OCSF)format.
Known False Positives
AWS Administrators may disable MFA but it is highly unlikely for this event to occur without prior notice to the company
Associated Analytic Story
|64.0||80||80||User $user_name$ has disabled Multi-Factor authentication for AWS account $aws_account_id$|
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
source | version: 1