Detect Renamed 7-Zip
Description
The following analytic detects the usage of a renamed 7-Zip executable using Sysmon data. It leverages the OriginalFileName field to identify instances where the 7-Zip process has been renamed. This activity is significant as attackers often rename legitimate tools to evade detection while staging or exfiltrating data. If confirmed malicious, this behavior could indicate data exfiltration attempts or other unauthorized data manipulation, potentially leading to significant data breaches or loss of sensitive information. Analysts should validate the legitimacy of the 7-Zip executable and investigate parallel processes for further suspicious activities.
Query · spl
| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Processes
WHERE (
Processes.original_file_name=7z*.exe
AND
Processes.process_name!=7z*.exe
)
BY Processes.action Processes.dest Processes.original_file_name
Processes.parent_process Processes.parent_process_exec Processes.parent_process_guid
Processes.parent_process_id Processes.parent_process_name Processes.parent_process_path
Processes.process Processes.process_exec Processes.process_guid
Processes.process_hash Processes.process_id Processes.process_integrity_level
Processes.process_name Processes.process_path Processes.user
Processes.user_id Processes.vendor_product
| `drop_dm_object_name(Processes)`
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `detect_renamed_7_zip_filter`
Implementation guide
The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the Processes node of the Endpoint data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.
Known false positives
- Limited false positives, however this analytic will need to be modified for each environment if Sysmon is not used.
Analyst notes
Known false positives: Limited false positives, however this analytic will need to be modified for each environment if Sysmon is not used.