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Description

This analytic is to detect the creation of doas.conf file in linux host platform. This configuration file can be use by doas utility tool to allow or permit 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: f6343e86-6e09-11ec-9376-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
1
2
3
4
5
6
| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Filesystem where Filesystem.file_path IN ("*/etc/doas.conf") by Filesystem.dest Filesystem.file_create_time Filesystem.file_name Filesystem.process_guid Filesystem.file_path 
| `drop_dm_object_name(Filesystem)` 
| `security_content_ctime(lastTime)` 
| `security_content_ctime(firstTime)` 
| `linux_doas_conf_file_creation_filter`

Macros

The SPL above uses the following Macros:

:information_source: linux_doas_conf_file_creation_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
  • Filesystem.dest
  • Filesystem.file_create_time
  • Filesystem.file_name
  • Filesystem.process_guid
  • Filesystem.file_path

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

RBA

Risk Score Impact Confidence Message
49.0 70 70 A file $file_name$ is created in $file_path$ on $dest$

:information_source: 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

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

source | version: 1