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P4T12ICK
67 lines
3.0 KiB
YAML
67 lines
3.0 KiB
YAML
name: Detect HTML Help Spawn Child Process
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id: 723716de-ee55-4cd4-9759-c44e7e55ba4b
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version: 1
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date: '2021-02-11'
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author: Michael Haag, Splunk
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type: batch
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datamodel:
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- Endpoint
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description: The following analytic identifies hh.exe (HTML Help) execution of a Compiled
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HTML Help (CHM) that spawns a child process. This particular technique will load
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Windows script code from a compiled help file. CHM files may contain nearly any
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file type embedded, but only execute html/htm. Upon a successful execution, the
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following script engines may be used for execution - JScript, VBScript, VBScript.Encode,
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JScript.Encode, JScript.Compact. Analyst may identify vbscript.dll or jscript.dll
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loading into hh.exe upon execution. The "htm" and "html" file extensions were the
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only extensions observed to be supported for the execution of Shortcut commands
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or WSH script code. During investigation, identify script content origination. Review
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child process events and investigate further. hh.exe is natively found in C:\Windows\system32
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and C:\Windows\syswow64.
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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=hh.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_html_help_spawn_child_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, some legitimate applications (ex. web browsers)
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may spawn a child process. Filter as needed.
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references:
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- https://attack.mitre.org/techniques/T1218/001/
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- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1218.001/T1218.001.md
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- https://lolbas-project.github.io/lolbas/Binaries/Hh/
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- https://gist.github.com/mgeeky/cce31c8602a144d8f2172a73d510e0e7
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- https://cyberforensicator.com/2019/01/20/silence-dissecting-malicious-chm-files-and-performing-forensic-analysis/
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tags:
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analytic_story:
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- Suspicious Compiled HTML 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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dataset:
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- https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1218.001/atomic_red_team/windows-sysmon.log
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kill_chain_phases:
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- Actions on Objectives
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mitre_attack_id:
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- T1218.001
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nist:
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- PR.PT
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- DE.CM
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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_name
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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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security_domain: endpoint
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