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89 lines
3.2 KiB
YAML
89 lines
3.2 KiB
YAML
name: Detect HTML Help Renamed
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id: 62fed254-513b-460e-953d-79771493a9f3
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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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description: The following analytic identifies a renamed instance of hh.exe (HTML
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Help) executing a Compiled HTML Help (CHM). 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. Validate
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it is the legitimate version of hh.exe by reviewing the PE metadata. hh.exe is natively
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found in C:\Windows\system32 and C:\Windows\syswow64.
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search: '`sysmon` EventID=1 OriginalFileName=HH.exe NOT process_name=hh.exe | stats
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count min(_time) as firstTime max(_time) as lastTime by Computer, User, parent_process_name,
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process_name, OriginalFileName, process_path, CommandLine | rename Computer as dest
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| `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `detect_html_help_renamed_filter`'
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how_to_implement: To successfully implement this search, you need to be ingesting
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logs with the process name, parent process, and command-line executions from your
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endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the
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Sysmon TA. Tune and filter known instances where renamed hh.exe may be used.
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known_false_positives: Although unlikely a renamed instance of hh.exe will be used
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legitimately, 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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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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confidence: 100
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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/T1218.001/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: The following $process_name$ has been identified as renamed, spawning from
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$parent_process_name$.
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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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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: Computer
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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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- EventID
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- OriginalFileName
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- process_name
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- Computer
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- User
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- parent_process_name
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- process_path
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- CommandLine
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risk_score: 80
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security_domain: endpoint
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