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https://github.com/splunk/security_content
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Eric
89 lines
4.3 KiB
YAML
89 lines
4.3 KiB
YAML
name: Malicious InProcServer32 Modification
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id: 127c8d08-25ff-11ec-9223-acde48001122
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version: 8
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date: '2025-05-02'
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author: Michael Haag, Splunk
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status: production
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type: TTP
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description:
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The following analytic detects a process modifying the registry with
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a known malicious CLSID under InProcServer32. It leverages data from Endpoint Detection
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and Response (EDR) agents, focusing on registry modifications within the HKLM or
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HKCU Software Classes CLSID paths. This activity is significant as it may indicate
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an attempt to load a malicious DLL, potentially leading to code execution. If confirmed
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malicious, this could allow an attacker to persist in the environment, execute arbitrary
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code, or escalate privileges, posing a severe threat to system integrity and security.
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data_source:
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- Sysmon EventID 12
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- Sysmon EventID 13
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search:
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'| tstats `security_content_summariesonly` count FROM datamodel=Endpoint.Registry
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where Registry.registry_path="*\\CLSID\\{89565275-A714-4a43-912E-978B935EDCCC}\\InProcServer32\\(Default)"
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by Registry.action Registry.dest Registry.process_guid Registry.process_id Registry.registry_hive
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Registry.registry_path Registry.registry_key_name Registry.registry_value_data Registry.registry_value_name
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Registry.registry_value_type Registry.status Registry.user Registry.vendor_product
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| `drop_dm_object_name(Registry)` | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`
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| `malicious_inprocserver32_modification_filter`'
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how_to_implement:
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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 `Processes` 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:
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False positives should be limited, filter as needed. In our
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test case, Remcos used regsvr32.exe to modify the registry. It may be required,
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dependent upon the EDR tool producing registry events, to remove (Default) from
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the command-line.
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references:
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- https://bohops.com/2018/06/28/abusing-com-registry-structure-clsid-localserver32-inprocserver32/
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- https://tria.ge/210929-ap75vsddan
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- https://www.virustotal.com/gui/file/cb77b93150cb0f7fe65ce8a7e2a5781e727419451355a7736db84109fa215a89
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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:
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'| 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:
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A process identified on endpoint $dest$ modifying the registry with a known
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malicious clsid under InProcServer32.
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risk_objects:
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- field: dest
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type: system
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score: 80
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threat_objects: []
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tags:
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analytic_story:
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- Suspicious Regsvr32 Activity
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- Remcos
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asset_type: Endpoint
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mitre_attack_id:
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- T1218.010
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- T1112
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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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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/malware/remcos/remcos/windows-sysmon.log
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source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
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sourcetype: XmlWinEventLog
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