IMPORTANT: No additional bug fixes or documentation updates will be released for this version. For the latest information, see the current release documentation.

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Modification of Environment Variable via Unsigned or Untrusted Parent

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Modification of Environment Variable via Unsigned or Untrusted Parent

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Identifies modifications to an environment variable using the built-in launchctl command. Adversaries may execute their own malicious payloads by hijacking certain environment variables to load arbitrary libraries or bypass certain restrictions.

Rule type: query

Rule indices:

logs-endpoint.events.*

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:

https://github.com/rapid7/metasploit-framework/blob/master//modules/post/osx/escalate/tccbypass.rb

Tags:

Domain: Endpoint
OS: macOS
Use Case: Threat Detection
Tactic: Defense Evasion
Data Source: Elastic Defend

Version: 206

Rule authors:

Elastic

Rule license: Elastic License v2

Setup

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Setup

This rule requires data coming in from Elastic Defend.

Elastic Defend Integration Setup

Elastic Defend is integrated into the Elastic Agent using Fleet. Upon configuration, the integration allows the Elastic Agent to monitor events on your host and send data to the Elastic Security app.

Prerequisite Requirements:

Fleet is required for Elastic Defend.
To configure Fleet Server refer to the documentation.

The following steps should be executed in order to add the Elastic Defend integration on a macOS System:

Go to the Kibana home page and click "Add integrations".
In the query bar, search for "Elastic Defend" and select the integration to see more details about it.
Click "Add Elastic Defend".
Configure the integration name and optionally add a description.
Select the type of environment you want to protect, for MacOS it is recommended to select "Traditional Endpoints".
Select a configuration preset. Each preset comes with different default settings for Elastic Agent, you can further customize these later by configuring the Elastic Defend integration policy. Helper guide.
We suggest selecting "Complete EDR (Endpoint Detection and Response)" as a configuration setting, that provides "All events; all preventions"
Enter a name for the agent policy in "New agent policy name". If other agent policies already exist, you can click the "Existing hosts" tab and select an existing policy instead. For more details on Elastic Agent configuration settings, refer to the helper guide.
Click "Save and Continue".
To complete the integration, select "Add Elastic Agent to your hosts" and continue to the next section to install the Elastic Agent on your hosts. For more details on Elastic Defend refer to the helper guide.

Rule query

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event.category:process and host.os.type:macos and event.type:start and
  process.name:launchctl and
  (process.parent.code_signature.exists : false or process.parent.code_signature.trusted : false) and
  process.args:(setenv and not (ANT_HOME or
                                DBUS_LAUNCHD_SESSION_BUS_SOCKET or
                                EDEN_ENV or
                                LG_WEBOS_TV_SDK_HOME or
                                RUNTIME_JAVA_HOME or
                                WEBOS_CLI_TV or
                                JAVA*_HOME) and
                not *.vmoptions) and
  not process.parent.executable:("/Applications/IntelliJ IDEA CE.app/Contents/jbr/Contents/Home/lib/jspawnhelper" or
                                  /Applications/NoMachine.app/Contents/Frameworks/bin/nxserver.bin or
                                  /Applications/NoMachine.app/Contents/Frameworks/bin/nxserver.bin or
                                  /usr/local/bin/kr)

Framework: MITRE ATT&CK^TM

Tactic:
- Name: Defense Evasion
- ID: TA0005
- Reference URL: https://attack.mitre.org/tactics/TA0005/
Technique:
- Name: Hijack Execution Flow
- ID: T1574
- Reference URL: https://attack.mitre.org/techniques/T1574/
Sub-technique:
- Name: Path Interception by PATH Environment Variable
- ID: T1574.007
- Reference URL: https://attack.mitre.org/techniques/T1574/007/

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