PowerShell Suspicious Discovery Related Windows API Functions

This rule detects the use of discovery-related Windows API functions in PowerShell Scripts. Attackers can use these functions to perform various situational awareness related activities, like enumerating users, shares, sessions, domain trusts, groups, etc.

Rule type: query

Rule indices:

winlogbeat-*
logs-windows.*

Severity: medium

Risk score: 47

Runs every: 5m

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

Tags:

Elastic
Host
Windows
Threat Detection
Discovery

Version: 4

Rule authors:

Elastic

Rule license: Elastic License v2

Investigation guide

edit

## Triage and analysis.

### Investigating PowerShell Suspicious Discovery Related Windows API Functions

PowerShell is one of the main tools used by system administrators for automation, report routines, and other tasks.

Attackers can use PowerShell to interact with the Win32 API to bypass file based antivirus detections, using libraries
like PSReflect or Get-ProcAddress Cmdlet.

#### Possible investigation steps:

- Examine script content that triggered the detection.
- Investigate script execution chain (parent process tree).
- Inspect any file or network events from the suspicious PowerShell host process instance.
- If the action is suspicious for the user, check for any other activities done by the user in the last 48 hours.

### False Positive Analysis

- Verify whether the script content is malicious/harmful.

### Related Rules

- PowerShell PSReflect Script - 56f2e9b5-4803-4e44-a0a4-a52dc79d57fe

### Response and Remediation

- Immediate response should be taken to validate, investigate, and potentially contain the activity to prevent further
post-compromise behavior.

## Config

The 'PowerShell Script Block Logging' logging policy must be enabled.
Steps to implement the logging policy with with Advanced Audit Configuration:

```
Computer Configuration >
Administrative Templates >
Windows PowerShell >
Turn on PowerShell Script Block Logging (Enable)
```

Steps to implement the logging policy via registry:

```
reg add "hklm\SOFTWARE\Policies\Microsoft\Windows\PowerShell\ScriptBlockLogging" /v EnableScriptBlockLogging /t REG_DWORD /d 1
```

Rule query

edit

event.category:process and
  powershell.file.script_block_text : (
    NetShareEnum or
    NetWkstaUserEnum or
    NetSessionEnum or
    NetLocalGroupEnum or
    NetLocalGroupGetMembers or
    DsGetSiteName or
    DsEnumerateDomainTrusts or
    WTSEnumerateSessionsEx or
    WTSQuerySessionInformation or
    LsaGetLogonSessionData or
    QueryServiceObjectSecurity
  )

Framework: MITRE ATT&CK^TM

Tactic:
- Name: Discovery
- ID: TA0007
- Reference URL: https://attack.mitre.org/tactics/TA0007/
Technique:
- Name: Network Share Discovery
- ID: T1135
- Reference URL: https://attack.mitre.org/techniques/T1135/
Technique:
- Name: Permission Groups Discovery
- ID: T1069
- Reference URL: https://attack.mitre.org/techniques/T1069/
Sub-technique:
- Name: Local Groups
- ID: T1069.001
- Reference URL: https://attack.mitre.org/techniques/T1069/001/
Tactic:
- Name: Execution
- ID: TA0002
- Reference URL: https://attack.mitre.org/tactics/TA0002/
Technique:
- Name: Command and Scripting Interpreter
- ID: T1059
- Reference URL: https://attack.mitre.org/techniques/T1059/
Sub-technique:
- Name: PowerShell
- ID: T1059.001
- Reference URL: https://attack.mitre.org/techniques/T1059/001/
Technique:
- Name: Native API
- ID: T1106
- Reference URL: https://attack.mitre.org/techniques/T1106/

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