Name:Linux Sudoers Tmp File Creation id:be254a5c-63e7-11ec-89da-acde48001122 version:3 date:2024-09-30 author:Teoderick Contreras, Splunk status:production type:Anomaly Description:The following analytic detects the creation of the "sudoers.tmp" file, which occurs when editing the /etc/sudoers file using visudo or another editor on a Linux platform. This detection leverages filesystem data to identify the presence of "sudoers.tmp" files. Monitoring this activity is crucial as adversaries may exploit it to gain elevated privileges on a compromised host. If confirmed malicious, this activity could allow attackers to modify sudoers configurations, potentially granting them unauthorized access to execute commands as other users, including root, thereby compromising the system's security. Data_source:
-Sysmon for Linux EventID 11
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`
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. References: -https://forum.ubuntuusers.de/topic/sudo-visudo-gibt-etc-sudoers-tmp/ drilldown_searches: name:'View the detection results for - "$dest$"' search:'%original_detection_search% | search dest = "$dest$"' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' name:'View risk events for the last 7 days for - "$dest$"' search:'| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$") starthoursago=168 | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' tags: analytic_story: - 'Linux Privilege Escalation' - 'Linux Persistence Techniques' asset_type:Endpoint confidence:90 impact:80 message:A file $file_name$ is created in $file_path$ on $dest$ mitre_attack_id: - 'T1548.003' - 'T1548' observable: name:'dest' type:'Hostname' - role: - 'Victim' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' required_fields: - '_time' - 'Filesystem.dest' - 'Filesystem.file_create_time' - 'Filesystem.file_name' - 'Filesystem.process_guid' - 'Filesystem.file_path' risk_score:72 security_domain:endpoint
