Detection: Process Deleting Its Process File Path

Updated Date: 2024-05-27 ID: f7eda4bc-871c-11eb-b110-acde48001122 Author: Teoderick Contreras Type: TTP Product: Splunk Enterprise Security

Description

The following analytic identifies a process attempting to delete its own file path, a behavior often associated with defense evasion techniques. This detection leverages Sysmon EventCode 1 logs, focusing on command lines executed via cmd.exe that include deletion commands. This activity is significant as it may indicate malware, such as Clop ransomware, trying to evade detection by removing its executable file if certain conditions are met. If confirmed malicious, this could allow the attacker to persist undetected, complicating incident response and remediation efforts.

1`sysmon` EventCode=1 CommandLine = "* /c *" CommandLine = "* del*" Image = "*\\cmd.exe" 
2| eval result = if(like(process,"%".parent_process."%"), "Found", "Not Found") 
3| stats min(_time) as firstTime max(_time) as lastTime count by dest user ParentImage ParentCommandLine Image CommandLine EventCode ProcessID result 
4| where result = "Found" 
5| `security_content_ctime(firstTime)` 
6| `security_content_ctime(lastTime)` 
7| `process_deleting_its_process_file_path_filter`

Data Source

Name Platform Sourcetype Source Supported App
CrowdStrike ProcessRollup2 N/A 'crowdstrike:events:sensor' 'crowdstrike' N/A

Macros Used

Name Value
security_content_ctime convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)
process_deleting_its_process_file_path_filter search *
process_deleting_its_process_file_path_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK
+ Kill Chain Phases
+ NIST
+ CIS
- Threat Actors
ID Technique Tactic
T1070 Indicator Removal Defense Evasion
KillChainPhase.EXPLOITAITON
NistCategory.DE_CM
Cis18Value.CIS_10
APT5
Lazarus Group

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Setting Value
Disabled true
Cron Schedule 0 * * * *
Earliest Time -70m@m
Latest Time -10m@m
Schedule Window auto
Creates Notable Yes
Rule Title %name%
Rule Description %description%
Notable Event Fields user, dest
Creates Risk Event True
This configuration file applies to all detections of type TTP. These detections will use Risk Based Alerting and generate Notable Events.

Implementation

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

unknown

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
A process $Image$ tries to delete its process path in commandline $CommandLine$ as part of defense evasion in host $dest$ by user $user$ 60 60 100
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

References

Detection Testing

Test Type Status Dataset Source Sourcetype
Validation ✅ Passing N/A N/A N/A
Unit ✅ Passing Dataset XmlWinEventLog:Microsoft-Windows-Sysmon/Operational xmlwineventlog
Integration ✅ Passing Dataset XmlWinEventLog:Microsoft-Windows-Sysmon/Operational xmlwineventlog

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: GitHub | Version: 3