mirror of
https://github.com/splunk/security_content
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Gowthamaraj rajendran
91 lines
4.3 KiB
YAML
91 lines
4.3 KiB
YAML
name: Malicious InProcServer32 Modification
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id: 127c8d08-25ff-11ec-9223-acde48001122
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version: 1
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date: '2021-10-05'
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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: The following analytic identifies a process modifying the registry with
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a known malicious CLSID under InProcServer32. Most COM classes are registered with
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the operating system and are identified by a GUID that represents the Class Identifier
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(CLSID) within the registry (usually under HKLM\\Software\\Classes\\CLSID or HKCU\\Software\\Classes\\CLSID). Behind
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the implementation of a COM class is the server (some binary) that is referenced
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within registry keys under the CLSID. The LocalServer32 key represents a path to
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an executable (exe) implementation, and the InprocServer32 key represents a path
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to a dynamic link library (DLL) implementation (Bohops). During triage, review parallel
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processes for suspicious activity. Pivot on the process GUID to see the full timeline
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of events. Analyze the value and look for file modifications. Being this is looking
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for inprocserver32, a DLL found in the value will most likely be loaded by a parallel
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process.
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data_source:
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- Sysmon Event ID 1
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search: '| tstats `security_content_summariesonly` count FROM datamodel=Endpoint.Processes
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by _time Processes.process_id Processes.process_name Processes.dest Processes.process_guid
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Processes.user | `drop_dm_object_name(Processes)` | join process_guid [| tstats
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`security_content_summariesonly` count FROM datamodel=Endpoint.Registry where Registry.registry_path=
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"*\\CLSID\\{89565275-A714-4a43-912E-978B935EDCCC}\\InProcServer32\\(Default)" by
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Registry.registry_path Registry.registry_key_name Registry.registry_value_name Registry.dest
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Registry.process_guid Registry.user | `drop_dm_object_name(Registry)` | fields _time
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dest registry_path registry_key_name registry_value_name process_name process_path
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process process_guid user] | stats count min(_time) as firstTime max(_time) as lastTime
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by dest, process_name registry_path registry_key_name registry_value_name user |
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`security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `malicious_inprocserver32_modification_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 `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: 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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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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confidence: 100
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impact: 80
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message: The $process_name$ was identified on endpoint $dest$ modifying the registry
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with a known malicious clsid under InProcServer32.
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mitre_attack_id:
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- T1218.010
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- T1112
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observable:
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- name: dest
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type: Hostname
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role:
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- Victim
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- name: process_name
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type: Process
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role:
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- Child Process
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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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required_fields:
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- _time
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- dest
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- process_name
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- registry_path
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- registry_key_name
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- registry_value_name
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- user
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risk_score: 80
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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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