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Windows Firewall Disabled via PowerShell

Elastic Stack Serverless Security

Identifies when the Windows Firewall is disabled using PowerShell cmdlets, which can help attackers evade network constraints, like internet and network lateral communication restrictions.

Rule type: eql

Rule indices:

  • logs-endpoint.events.*
  • winlogbeat-*
  • logs-windows.*

Severity: medium

Risk score: 47

Runs every: 5m

Searches indices from: now-9m (https://www.elastic.co/guide/en/elasticsearch/reference/current/common-options.html#date-math[Date Math format], see also Additional look-back time)

Maximum alerts per execution: 100

References:

Tags:

  • Elastic
  • Host
  • Windows
  • Threat Detection
  • Defense Evasion

Version: 5

Rule authors:

  • Austin Songer

Rule license: Elastic License v2

Investigation guide

Windows Defender Firewall is a native component that provides host-based, two-way network traffic filtering for a
device and blocks unauthorized network traffic flowing into or out of the local device.

Attackers can disable the Windows firewall or its rules to enable lateral movement and command and control activity.

This rule identifies patterns related to disabling the Windows firewall or its rules using the Set-NetFirewallProfile
PowerShell cmdlet.

  • Investigate the process execution chain (parent process tree) for unknown processes. Examine their executable files
    for prevalence, whether they are located in expected locations, and if they are signed with valid digital signatures.
  • Identify the user account that performed the action and whether it should perform this kind of action.
  • Contact the account owner and confirm whether they are aware of this activity.
  • Investigate other alerts associated with the user/host during the past 48 hours.
  • Inspect the host for suspicious or abnormal behaviors in the alert timeframe.
  • This mechanism can be used legitimately. Check whether the user is an administrator and is legitimately performing
    troubleshooting.
  • In case of an allowed benign true positive (B-TP), assess adding rules to allow needed traffic and re-enable the firewall.
  • Initiate the incident response process based on the outcome of the triage.
  • Isolate the involved hosts to prevent further post-compromise behavior.
  • Re-enable the firewall with its desired configurations.
  • Investigate credential exposure on systems compromised or used by the attacker to ensure all compromised accounts are
    identified. Reset passwords for these accounts and other potentially compromised credentials, such as email, business
    systems, and web services.
  • Review the privileges assigned to the involved users to ensure that the least privilege principle is being followed.
  • Determine the initial vector abused by the attacker and take action to prevent reinfection through the same vector.
  • Using the incident response data, update logging and audit policies to improve the mean time to detect (MTTD) and the
    mean time to respond (MTTR).

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.

Rule query

process where event.action == "start" and
  (process.name : ("powershell.exe", "pwsh.exe", "powershell_ise.exe") or process.pe.original_file_name == "PowerShell.EXE") and
   process.args : "*Set-NetFirewallProfile*" and
  (process.args : "*-Enabled*" and process.args : "*False*") and
  (process.args : "*-All*" or process.args : ("*Public*", "*Domain*", "*Private*"))

Framework: MITRE ATT&CKTM