splunk-security_content/docs/_posts/2021-12-23-linux_sudoers_tmp_file_creation.md

title, excerpt, categories, last_modified_at, toc, toc_label, tags

title	excerpt	categories	last_modified_at	toc	toc_label	tags
Linux Sudoers Tmp File Creation	Sudo and Sudo Caching, Abuse Elevation Control Mechanism	Endpoint	2021-12-23	true		Sudo and Sudo Caching Privilege Escalation Defense Evasion Abuse Elevation Control Mechanism Privilege Escalation Defense Evasion Splunk Enterprise Splunk Enterprise Security Splunk Cloud Endpoint

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Description

This analytic is to looks for file creation of sudoers.tmp file cause by editing /etc/sudoers using visudo or editor in linux platform. This technique may abuse by adversaries, malware author and red teamers to gain elevated privilege to targeted or compromised host. /etc/sudoers file controls who can run what commands as what users on what machines and can also control special things such as whether you need a password for particular commands. The file is composed of aliases (basically variables) and user specifications (which control who can run what).

• Type: Anomaly
• Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
• Datamodel: Endpoint
• Last Updated: 2021-12-23
• Author: Teoderick Contreras, Splunk
• ID: be254a5c-63e7-11ec-89da-acde48001122

ATT&CK

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

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

Search

| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Filesystem where Filesystem.file_path IN ("*sudoers.tmp*") by Filesystem.dest Filesystem.file_name Filesystem.process_guid Filesystem.file_path 
| `drop_dm_object_name(Filesystem)` 
| `security_content_ctime(lastTime)` 
| `security_content_ctime(firstTime)` 
| `linux_sudoers_tmp_file_creation_filter`

Associated Analytic Story

• Linux Privilege Escalation
• Linux Persistence Techniques

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.

Required field

• _time
• Filesystem.dest
• Filesystem.file_create_time
• Filesystem.file_name
• Filesystem.process_guid
• Filesystem.file_path

Kill Chain Phase

• Privilege Escalation

Known False Positives

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

RBA

Risk Score	Impact	Confidence	Message
72.0	80	90	A file file_name is created in file_path on dest

Reference

• https://forum.ubuntuusers.de/topic/sudo-visudo-gibt-etc-sudoers-tmp/

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/sudoers_temp/sysmon_linux.log

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