Identifies the creation of a hidden local user account by appending the dollar sign to the account name. This is sometimes done by attackers to increase access to a system and avoid appearing in the results of accounts listing using the net users command.
Rule type: eql
Risk score: 73
Runs every: 5m
Maximum alerts per execution: 100
- Threat Detection
Rule license: Elastic License v2
## Triage and analysis ### Investigating Creation of a Hidden Local User Account Attackers can create accounts ending with a `$` symbol to make the account hidden to user enumeration utilities and bypass detections that identify computer accounts by this pattern to apply filters. This rule uses registry events to identify the creation of local hidden accounts. #### Possible investigation steps - Identify the user account which performed the action and whether it should perform this kind of action. - Investigate the script execution chain (parent process tree). - Investigate other alerts related to the user/host in the last 48 hours. ### False positive analysis - This activity is unlikely to happen legitimately. Benign true positive (B-TPs) can be added as exceptions if necessary. ### Response and remediation - Initiate the incident response process based on the outcome of the triage. - Quarantine the involved host to prevent further post-compromise behavior. - Delete the hidden account. - Review the privileges of the involved accounts. ## Config If enabling an EQL rule on a non-elastic-agent index (such as beats) for versions <8.2, events will not define `event.ingested` and default fallback for EQL rules was not added until 8.2, so you will need to add a custom pipeline to populate `event.ingested` to @timestamp for this rule to work.
registry where registry.path : "HKLM\\SAM\\SAM\\Domains\\Account\\Users\\Names\\*$\\"
Framework: MITRE ATT&CKTM
- Name: Persistence
- ID: TA0003
- Reference URL: https://attack.mitre.org/tactics/TA0003/
- Name: Create Account
- ID: T1136
- Reference URL: https://attack.mitre.org/techniques/T1136/
- Name: Local Account
- ID: T1136.001
- Reference URL: https://attack.mitre.org/techniques/T1136/001/