Detection: MacOS plutil

Updated Date: 2024-05-22 ID: c11f2b57-92c1-4cd2-b46c-064eafb833ac Author: Patrick Bareiss, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects the usage of the plutil command to modify plist files on macOS systems. It leverages osquery to monitor process events, specifically looking for executions of /usr/bin/plutil. This activity is significant because adversaries can use plutil to alter plist files, potentially adding malicious binaries or command-line arguments that execute upon user logon or system startup. If confirmed malicious, this could allow attackers to achieve persistence, execute arbitrary code, or escalate privileges, posing a significant threat to the system's security.

1`osquery_macro` name=es_process_events columns.path=/usr/bin/plutil 
2| rename columns.* as * 
3| stats count  min(_time) as firstTime max(_time) as lastTime by username host cmdline pid path parent signing_id 
4| rename username as user, cmdline as process, path as process_path, host as dest 
5| `security_content_ctime(firstTime)`
6| `security_content_ctime(lastTime)` 
7| `macos_plutil_filter`

Data Source

Name Platform Sourcetype Source Supported App
osquery N/A 'osquery:results' 'osquery' N/A

Macros Used

Name Value
osquery_macro sourcetype=osquery:results
macos_plutil_filter search *
macos_plutil_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK
+ Kill Chain Phases
+ NIST
+ CIS
- Threat Actors
ID Technique Tactic
T1647 Plist File Modification Defense Evasion
KillChainPhase.EXPLOITAITON
NistCategory.DE_CM
Cis18Value.CIS_10

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Setting Value
Disabled true
Cron Schedule 0 * * * *
Earliest Time -70m@m
Latest Time -10m@m
Schedule Window auto
Creates Notable Yes
Rule Title %name%
Rule Description %description%
Notable Event Fields user, dest
Creates Risk Event True
This configuration file applies to all detections of type TTP. These detections will use Risk Based Alerting and generate Notable Events.

Implementation

This detection uses osquery and endpoint security on MacOS. Follow the link in references, which describes how to setup process auditing in MacOS with endpoint security and osquery.

Known False Positives

Administrators using plutil to change plist files.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
plutil are executed on $dest$ from $user$ 25 50 50
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

References

Detection Testing

Test Type Status Dataset Source Sourcetype
Validation ✅ Passing N/A N/A N/A
Unit ✅ Passing Dataset osquery osquery:results
Integration ✅ Passing Dataset osquery osquery:results

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

Source: GitHub | Version: 4