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P4T12ICK
89 lines
3.3 KiB
YAML
89 lines
3.3 KiB
YAML
name: Detect Regasm Spawning a Process
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id: 72170ec5-f7d2-42f5-aefb-2b8be6aad15f
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version: 1
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date: '2021-02-12'
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author: Michael Haag, Splunk
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type: TTP
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datamodel:
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- Endpoint
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description: The following analytic identifies regasm.exe spawning a process. This
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particular technique has been used in the wild to bypass application control products.
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Regasm.exe and Regsvcs.exe are signed by Microsoft. Spawning of a child process
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is rare from either process and should be investigated further. During investigation,
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identify and retrieve the content being loaded. Review parallel processes for additional
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suspicious behavior. Gather any other file modifications and review accordingly.
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regsvcs.exe and regasm.exe are natively found in C:\Windows\Microsoft.NET\Framework\v*\regasm|regsvcs.exe
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and C:\Windows\Microsoft.NET\Framework64\v*\regasm|regsvcs.exe.
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search: '| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time)
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as lastTime from datamodel=Endpoint.Processes where Processes.parent_process_name=regasm.exe
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by Processes.dest Processes.user Processes.parent_process Processes.process_name
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Processes.process Processes.process_id Processes.parent_process_id | `drop_dm_object_name(Processes)`
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| `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `detect_regasm_spawning_a_process_filter`'
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how_to_implement: To successfully implement this search you need to be ingesting information
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on process that include the name of the process responsible for the changes from
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your endpoints into the `Endpoint` datamodel in the `Processes` node.
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known_false_positives: Although unlikely, limited instances of regasm.exe or regsvcs.exe
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may cause a false positive. Filter based endpoint usage, command line arguments,
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or process lineage.
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references:
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- https://attack.mitre.org/techniques/T1218/009/
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- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1218.009/T1218.009.md
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- https://lolbas-project.github.io/lolbas/Binaries/Regsvcs/
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- https://lolbas-project.github.io/lolbas/Binaries/Regasm/
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tags:
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analytic_story:
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- Suspicious Regsvcs Regasm Activity
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asset_type: Endpoint
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automated_detection_testing: passed
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cis20:
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- CIS 8
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confidence: 80
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context:
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- Source:Endpoint
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- Stage:Defense Evasion
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dataset:
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- https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1218.009/atomic_red_team/windows-sysmon.log
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impact: 80
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kill_chain_phases:
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- Actions on Objectives
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message: An instance of $parent_process_name$ spawning $process_name$ was identified
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on endpoint $dest$ by user $user$ spawning a child process, typically not normal
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behavior for $parent_process_name$.
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mitre_attack_id:
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- T1218.009
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nist:
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- PR.PT
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- DE.CM
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observable:
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- name: user
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type: User
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role:
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- Victim
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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: parent_process_name
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type: Parent Process
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role:
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- Parent Process
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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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- Processes.parent_process_name
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- Processes.dest
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- Processes.user
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- Processes.parent_process
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- Processes.process
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- Processes.process_id
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- Processes.parent_process_id
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risk_score: 64
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security_domain: endpoint
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