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Eric
86 lines
4.9 KiB
YAML
86 lines
4.9 KiB
YAML
name: Windows RunMRU Command Execution
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id: a15aa1ab-2b79-467f-8201-65e0f32d5b1a
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version: 6
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date: '2025-05-02'
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author: Nasreddine Bencherchali, Michael Haag, Splunk
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data_source:
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- Sysmon EventID 12
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- Sysmon EventID 13
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type: Anomaly
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status: production
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description: The following analytic detects modifications to the Windows RunMRU registry
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key, which stores a history of commands executed through the Run dialog box (Windows+R).
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It leverages Endpoint Detection and Response (EDR) telemetry to monitor registry
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events targeting this key. This activity is significant as malware often uses the
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Run dialog to execute malicious commands while attempting to appear legitimate.
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If confirmed malicious, this could indicate an attacker using indirect command execution
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techniques for defense evasion or persistence. The detection excludes MRUList value
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changes to focus on actual command entries.
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search: '| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Registry where Registry.registry_path="*\\Microsoft\\Windows\\CurrentVersion\\Explorer\\RunMRU*" NOT Registry.registry_value_name="MRUList" NOT Registry.registry_value_data="unknown" by Registry.dest Registry.registry_value_data Registry.action Registry.process_guid Registry.process_id Registry.registry_key_name Registry.user Registry.registry_path Registry.registry_hive Registry.registry_value_name Registry.status Registry.vendor_product | `drop_dm_object_name(Registry)` | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `windows_runmru_command_execution_filter`'
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how_to_implement: The detection is based on data that originates from Endpoint Detection
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and Response (EDR) agents. These agents are designed to provide security-related
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telemetry from the endpoints where the agent is installed. To implement this search,
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you must ingest logs that contain the process GUID, process name, and parent process.
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Additionally, you must ingest complete command-line executions. These logs must
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be processed using the appropriate Splunk Technology Add-ons that are specific to
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the EDR product. The logs must also be mapped to the `Registry` node of the `Endpoint`
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data model. Use the Splunk Common Information Model (CIM) to normalize the field
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names and speed up the data modeling process.
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known_false_positives: This detection may generate a few false positives, such as
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legitimate software updates or legitimate system maintenance activities that modify
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the RunMRU key. However, the exclusion of MRUList value changes helps reduce the
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number of false positives by focusing only on actual command entries. Add any specific
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false positives to the built in filter to reduce findings as needed.
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references:
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- https://medium.com/@ahmed.moh.farou2/fake-captcha-campaign-on-arabic-pirated-movie-sites-delivers-lumma-stealer-4f203f7adabf
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- https://medium.com/@shaherzakaria8/downloading-trojan-lumma-infostealer-through-capatcha-1f25255a0e71
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- https://www.forensafe.com/blogs/runmrukey.html
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- https://github.com/SigmaHQ/sigma/blob/master/rules-threat-hunting/windows/registry/registry_set/registry_set_runmru_command_execution.yml
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drilldown_searches:
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- name: View the detection results for - "$dest$"
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search: '%original_detection_search% | search dest = "$dest$"'
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earliest_offset: $info_min_time$
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latest_offset: $info_max_time$
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- name: View risk events for the last 7 days for - "$dest$"
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search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$")
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starthoursago=168 | stats count min(_time) as firstTime max(_time) as lastTime
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values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories)
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as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic)
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as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)`
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| `security_content_ctime(lastTime)`'
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earliest_offset: $info_min_time$
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latest_offset: $info_max_time$
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rba:
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message: An instance of $registry_value_data$ was identified on endpoint $dest$
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by user $user$ attempting to execute a command through the Run dialog box.
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risk_objects:
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- field: dest
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type: system
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score: 48
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- field: user
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type: user
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score: 48
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threat_objects:
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- field: registry_value_data
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type: registry_value_text
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tags:
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analytic_story:
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- Lumma Stealer
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asset_type: Endpoint
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mitre_attack_id:
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- T1202
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product:
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- Splunk Enterprise
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- Splunk Enterprise Security
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- Splunk Cloud
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security_domain: endpoint
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cve: []
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atomic_guid:
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- de323a93-2f18-4bd5-ba60-d6fca6aeff76
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tests:
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- name: True Positive Test
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attack_data:
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- data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1202/atomic_red_team/windows-sysmon_runmru.log
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source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
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sourcetype: XmlWinEventLog
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