splunk-security_content/docs/_posts/2022-01-05-linux_doas_tool_execution.md

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title	excerpt	categories	last_modified_at	toc	toc_label	tags
Linux Doas Tool Execution	Sudo and Sudo Caching , Abuse Elevation Control Mechanism	Endpoint	2022-01-05	true		Sudo and Sudo Caching Abuse Elevation Control Mechanism Defense Evasion Privilege Escalation Defense Evasion Privilege Escalation Splunk Enterprise Splunk Enterprise Security Splunk Cloud Endpoint

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Description

This analytic is to detect the doas tool execution in linux host platform. This utility tool allow standard users to perform tasks as root, the same way sudo does. This tool is developed as a minimalistic alternative to sudo application. This tool can be abused advesaries, attacker or malware to gain elevated privileges to the targeted or compromised host. On the other hand this can also be executed by administrator for a certain task that needs admin rights. In this case filter is needed.

• Type: Anomaly
• Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
• Datamodel: Endpoint
• Last Updated: 2022-01-05
• Author: Teoderick Contreras, Splunk
• ID: d5a62490-6e09-11ec-884e-acde48001122

Annotations

ATT&CK

ID	Technique	Tactic
T1548.003	Sudo and Sudo Caching	Defense Evasion, Privilege Escalation

| T1548 | Abuse Elevation Control Mechanism | Defense Evasion, Privilege Escalation |

Kill Chain Phase

• Exploitation

NIST

• DE.CM

CIS20

• CIS 3
• CIS 5
• CIS 16

CVE

Search

| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.process_name = "doas" by Processes.dest Processes.user Processes.parent_process_name Processes.process_name Processes.process Processes.process_id Processes.parent_process_id Processes.process_guid 
| `drop_dm_object_name(Processes)` 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `linux_doas_tool_execution_filter`

Macros

The SPL above uses the following Macros:

• security_content_ctime
• security_content_summariesonly

ℹ️ linux_doas_tool_execution_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required field

• _time
• Processes.dest
• Processes.user
• Processes.parent_process_name
• Processes.process_name
• Processes.process
• Processes.process_id
• Processes.parent_process_id

How To Implement

To successfully implement this search, you need to be ingesting logs with the process name, parent process, and command-line executions from your endpoints. If you are using Sysmon, you can use the Add-on for Linux Sysmon from Splunkbase.

Known False Positives

Administrator or network operator can execute this command. Please update the filter macros to remove false positives.

Associated Analytic story

• Linux Privilege Escalation
• Linux Persistence Techniques

RBA

Risk Score	Impact	Confidence	Message
49.0	70	70	A doas process_name with commandline process was executed on dest

ℹ️ The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

Reference

• https://wiki.gentoo.org/wiki/Doas
• https://www.makeuseof.com/how-to-install-and-use-doas/

Test Dataset

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

• https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1548.003/doas_exec/sysmon_linux.log

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