Suspicious Microsoft Office Child Process

Status: test
Severity: high
Log source: product windows, category process_creation
Author: Florian Roth (Nextron Systems), Markus Neis, FPT.EagleEye Team, Vadim Khrykov, Cyb3rEng, Michael Haag, Christopher Peacock @securepeacock, @scythe_io
Source: github.com/SigmaHQ/sigma

Detects a suspicious process spawning from one of the Microsoft Office suite products (Word, Excel, PowerPoint, Publisher, Visio, etc.)

MITRE ATT&CK coverage

Tactic	Techniques
Execution	`T1047` Windows Management Instrumentation, `T1204.002` User Execution: Malicious File
Stealth	`T1218.010` System Binary Proxy Execution: Regsvr32

Event coverage

Provider	Event	Title
Sysmon	Event ID 1	Process creation

Rule body yaml

title: Suspicious Microsoft Office Child Process
id: 438025f9-5856-4663-83f7-52f878a70a50
related:
    - id: c27515df-97a9-4162-8a60-dc0eeb51b775 # Speicifc OneNote rule due to its recent usage in phishing attacks
      type: derived
    - id: e1693bc8-7168-4eab-8718-cdcaa68a1738
      type: derived
    - id: 23daeb52-e6eb-493c-8607-c4f0246cb7d8
      type: obsolete
    - id: 518643ba-7d9c-4fa5-9f37-baed36059f6a
      type: obsolete
    - id: 04f5363a-6bca-42ff-be70-0d28bf629ead
      type: obsolete
status: test
description: Detects a suspicious process spawning from one of the Microsoft Office suite products (Word, Excel, PowerPoint, Publisher, Visio, etc.)
references:
    - https://www.hybrid-analysis.com/sample/465aabe132ccb949e75b8ab9c5bda36d80cf2fd503d52b8bad54e295f28bbc21?environmentId=100
    - https://mgreen27.github.io/posts/2018/04/02/DownloadCradle.html
    - https://thedfirreport.com/2021/03/29/sodinokibi-aka-revil-ransomware/
    - https://doublepulsar.com/follina-a-microsoft-office-code-execution-vulnerability-1a47fce5629e
    - https://github.com/vadim-hunter/Detection-Ideas-Rules/blob/02bcbfc2bfb8b4da601bb30de0344ae453aa1afe/Threat%20Intelligence/The%20DFIR%20Report/20210329_Sodinokibi_(aka_REvil)_Ransomware.yaml
    - https://github.com/splunk/security_content/blob/300af51b88ad5d5b27ce4f5f54e4d6e6a3a2c06d/detections/endpoint/office_spawning_control.yml
    - https://twitter.com/andythevariable/status/1576953781581144064?s=20&t=QiJILvK4ZiBdR8RJe24u-A
    - https://www.elastic.co/security-labs/exploring-the-ref2731-intrusion-set
    - https://github.com/elastic/detection-rules/blob/c76a39796972ecde44cb1da6df47f1b6562c9770/rules/windows/defense_evasion_execution_msbuild_started_by_office_app.toml
    - https://www.vmray.com/analyses/2d2fa29185ad/report/overview.html
    - https://app.any.run/tasks/c903e9c8-0350-440c-8688-3881b556b8e0/
author: Florian Roth (Nextron Systems), Markus Neis, FPT.EagleEye Team, Vadim Khrykov, Cyb3rEng, Michael Haag, Christopher Peacock @securepeacock, @scythe_io
date: 2018-04-06
modified: 2023-04-24
tags:
    - attack.execution
    - attack.stealth
    - attack.t1047
    - attack.t1204.002
    - attack.t1218.010
logsource:
    category: process_creation
    product: windows
detection:
    selection_parent:
        ParentImage|endswith:
            - '\EQNEDT32.EXE'
            - '\EXCEL.EXE'
            - '\MSACCESS.EXE'
            - '\MSPUB.exe'
            - '\ONENOTE.EXE'
            - '\POWERPNT.exe'
            - '\VISIO.exe'
            - '\WINWORD.EXE'
            - '\wordpad.exe'
            - '\wordview.exe'
    selection_child_processes:
        - OriginalFileName:
              - 'bitsadmin.exe'
              - 'CertOC.exe'
              - 'CertUtil.exe'
              - 'Cmd.Exe'
              - 'CMSTP.EXE'
              - 'cscript.exe'
              - 'curl.exe'
              - 'HH.exe'
              - 'IEExec.exe'
              - 'InstallUtil.exe'
              - 'javaw.exe'
              - 'Microsoft.Workflow.Compiler.exe'
              - 'msdt.exe'
              - 'MSHTA.EXE'
              - 'msiexec.exe'
              - 'Msxsl.exe'
              - 'odbcconf.exe'
              - 'pcalua.exe'
              - 'PowerShell.EXE'
              - 'RegAsm.exe'
              - 'RegSvcs.exe'
              - 'REGSVR32.exe'
              - 'RUNDLL32.exe'
              - 'schtasks.exe'
              - 'ScriptRunner.exe'
              - 'wmic.exe'
              - 'WorkFolders.exe'
              - 'wscript.exe'
        - Image|endswith:
              - '\AppVLP.exe'
              - '\bash.exe'
              - '\bitsadmin.exe'
              - '\certoc.exe'
              - '\certutil.exe'
              - '\cmd.exe'
              - '\cmstp.exe'
              - '\control.exe'
              - '\cscript.exe'
              - '\curl.exe'
              - '\forfiles.exe'
              - '\hh.exe'
              - '\ieexec.exe'
              - '\installutil.exe'
              - '\javaw.exe'
              - '\mftrace.exe'
              - '\Microsoft.Workflow.Compiler.exe'
              - '\msbuild.exe'
              - '\msdt.exe'
              - '\mshta.exe'
              - '\msidb.exe'
              - '\msiexec.exe'
              - '\msxsl.exe'
              - '\odbcconf.exe'
              - '\pcalua.exe'
              - '\powershell.exe'
              - '\pwsh.exe'
              - '\regasm.exe'
              - '\regsvcs.exe'
              - '\regsvr32.exe'
              - '\rundll32.exe'
              - '\schtasks.exe'
              - '\scrcons.exe'
              - '\scriptrunner.exe'
              - '\sh.exe'
              - '\svchost.exe'
              - '\verclsid.exe'
              - '\wmic.exe'
              - '\workfolders.exe'
              - '\wscript.exe'
    selection_child_susp_paths: # Idea: Laiali Kazalbach, Mohamed Elsayed (#4142)
        Image|contains:
            - '\AppData\'
            - '\Users\Public\'
            - '\ProgramData\'
            - '\Windows\Tasks\'
            - '\Windows\Temp\'
            - '\Windows\System32\Tasks\'
    condition: selection_parent and 1 of selection_child_*
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: `condition`

selection_parent and 1 of selection_child_*

Stage 1: `selection_parent`

selection_parent:
    ParentImage|endswith:
        - '\EQNEDT32.EXE'
        - '\EXCEL.EXE'
        - '\MSACCESS.EXE'
        - '\MSPUB.exe'
        - '\ONENOTE.EXE'
        - '\POWERPNT.exe'
        - '\VISIO.exe'
        - '\WINWORD.EXE'
        - '\wordpad.exe'
        - '\wordview.exe'

Stage 2: `selection_child_processes`

selection_child_processes:
    - OriginalFileName:
          - 'bitsadmin.exe'
          - 'CertOC.exe'
          - 'CertUtil.exe'
          - 'Cmd.Exe'
          - 'CMSTP.EXE'
          - 'cscript.exe'
          - 'curl.exe'
          - 'HH.exe'
          - 'IEExec.exe'
          - 'InstallUtil.exe'
          - 'javaw.exe'
          - 'Microsoft.Workflow.Compiler.exe'
          - 'msdt.exe'
          - 'MSHTA.EXE'
          - 'msiexec.exe'
          - 'Msxsl.exe'
          - 'odbcconf.exe'
          - 'pcalua.exe'
          - 'PowerShell.EXE'
          - 'RegAsm.exe'
          - 'RegSvcs.exe'
          - 'REGSVR32.exe'
          - 'RUNDLL32.exe'
          - 'schtasks.exe'
          - 'ScriptRunner.exe'
          - 'wmic.exe'
          - 'WorkFolders.exe'
          - 'wscript.exe'
    - Image|endswith:
          - '\AppVLP.exe'
          - '\bash.exe'
          - '\bitsadmin.exe'
          - '\certoc.exe'
          - '\certutil.exe'
          - '\cmd.exe'
          - '\cmstp.exe'
          - '\control.exe'
          - '\cscript.exe'
          - '\curl.exe'
          - '\forfiles.exe'
          - '\hh.exe'
          - '\ieexec.exe'
          - '\installutil.exe'
          - '\javaw.exe'
          - '\mftrace.exe'
          - '\Microsoft.Workflow.Compiler.exe'
          - '\msbuild.exe'
          - '\msdt.exe'
          - '\mshta.exe'
          - '\msidb.exe'
          - '\msiexec.exe'
          - '\msxsl.exe'
          - '\odbcconf.exe'
          - '\pcalua.exe'
          - '\powershell.exe'
          - '\pwsh.exe'
          - '\regasm.exe'
          - '\regsvcs.exe'
          - '\regsvr32.exe'
          - '\rundll32.exe'
          - '\schtasks.exe'
          - '\scrcons.exe'
          - '\scriptrunner.exe'
          - '\sh.exe'
          - '\svchost.exe'
          - '\verclsid.exe'
          - '\wmic.exe'
          - '\workfolders.exe'
          - '\wscript.exe'

Stage 3: `selection_child_susp_paths`

selection_child_susp_paths:
    Image|contains:
        - '\AppData\'
        - '\Users\Public\'
        - '\ProgramData\'
        - '\Windows\Tasks\'
        - '\Windows\Temp\'
        - '\Windows\System32\Tasks\'

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

Field	Kind	Values
`Image`	ends_with	`\AppVLP.exe` corpus 6 (sigma 6) `\Microsoft.Workflow.Compiler.exe` corpus 3 (sigma 3) `\bash.exe` corpus 22 (sigma 22) `\bitsadmin.exe` corpus 29 (sigma 29) `\certoc.exe` corpus 10 (sigma 10) `\certutil.exe` corpus 43 (sigma 43) `\cmd.exe` corpus 130 (sigma 130) `\cmstp.exe` corpus 8 (sigma 8) `\control.exe` corpus 5 (sigma 5) `\cscript.exe` corpus 73 (sigma 73) `\curl.exe` corpus 30 (sigma 30) `\forfiles.exe` corpus 12 (sigma 12) `\hh.exe` corpus 16 (sigma 16) `\ieexec.exe` corpus 3 (sigma 3) `\installutil.exe` corpus 9 (sigma 9) `\javaw.exe` corpus 2 (sigma 2) `\mftrace.exe` corpus 6 (sigma 6) `\msbuild.exe` corpus 10 (sigma 10) `\msdt.exe` corpus 9 (sigma 9) `\mshta.exe` corpus 67 (sigma 67) `\msidb.exe` corpus 2 (sigma 2) `\msiexec.exe` corpus 21 (sigma 21) `\msxsl.exe` corpus 6 (sigma 6) `\odbcconf.exe` corpus 11 (sigma 11) `\pcalua.exe` corpus 3 (sigma 3) `\powershell.exe` corpus 182 (sigma 182) `\pwsh.exe` corpus 168 (sigma 168) `\regasm.exe` corpus 9 (sigma 9) `\regsvcs.exe` corpus 8 (sigma 8) `\regsvr32.exe` corpus 65 (sigma 65) `\rundll32.exe` corpus 95 (sigma 95) `\schtasks.exe` corpus 56 (sigma 56) `\scrcons.exe` corpus 9 (sigma 9) `\scriptrunner.exe` corpus 12 (sigma 12) `\sh.exe` corpus 16 (sigma 16) `\svchost.exe` corpus 23 (sigma 23) `\verclsid.exe` corpus 4 (sigma 4) `\wmic.exe` corpus 60 (sigma 60) `\workfolders.exe` corpus 2 (sigma 2) `\wscript.exe` corpus 75 (sigma 75)
`Image`	match	`\AppData\` corpus 7 (sigma 7) `\ProgramData\` corpus 2 (sigma 2) `\Users\Public\` corpus 10 (sigma 10) `\Windows\System32\Tasks\` corpus 3 (sigma 3) `\Windows\Tasks\` corpus 3 (sigma 3) `\Windows\Temp\` corpus 8 (sigma 8)
`OriginalFileName`	eq	`CMSTP.EXE` corpus 6 (sigma 5, elastic 1) `CertOC.exe` corpus 6 (sigma 6) `CertUtil.exe` corpus 21 (sigma 14, splunk 6, elastic 1) `Cmd.Exe` corpus 65 (sigma 43, splunk 17, elastic 5) `HH.exe` corpus 9 (sigma 5, splunk 4) `IEExec.exe` corpus 3 (sigma 3) `InstallUtil.exe` corpus 11 (sigma 6, splunk 4, elastic 1) `MSHTA.EXE` corpus 22 (sigma 13, splunk 6, elastic 3) `Microsoft.Workflow.Compiler.exe` corpus 6 (sigma 3, splunk 2, elastic 1) `Msxsl.exe` corpus 5 (sigma 3, elastic 2) `PowerShell.EXE` corpus 120 (sigma 84, splunk 30, elastic 6) `REGSVR32.exe` corpus 26 (sigma 17, splunk 6, elastic 3) `RUNDLL32.exe` corpus 62 (sigma 35, splunk 21, elastic 6) `RegAsm.exe` corpus 8 (sigma 6, elastic 1, splunk 1) `RegSvcs.exe` corpus 7 (sigma 5, elastic 1, splunk 1) `ScriptRunner.exe` corpus 3 (sigma 3) `WorkFolders.exe` corpus 2 (sigma 2) `bitsadmin.exe` corpus 12 (sigma 9, splunk 2, kusto 1) `cscript.exe` corpus 19 (sigma 17, elastic 2) `curl.exe` corpus 15 (sigma 12, splunk 3) `javaw.exe` corpus 2 (sigma 2) `msdt.exe` corpus 8 (sigma 6, elastic 2) `msiexec.exe` corpus 10 (sigma 5, splunk 4, elastic 1) `odbcconf.exe` corpus 9 (sigma 9) `pcalua.exe` corpus 2 (sigma 2) `schtasks.exe` corpus 23 (sigma 18, splunk 4, elastic 1) `wmic.exe` corpus 61 (sigma 36, splunk 18, elastic 7) `wscript.exe` corpus 20 (sigma 17, elastic 3)
`ParentImage`	ends_with	`\EQNEDT32.EXE` corpus 5 (sigma 5) `\EXCEL.EXE` corpus 8 (sigma 8) `\MSACCESS.EXE` corpus 4 (sigma 4) `\MSPUB.exe` corpus 4 (sigma 4) `\ONENOTE.EXE` corpus 5 (sigma 5) `\POWERPNT.exe` corpus 6 (sigma 6) `\VISIO.exe` corpus 4 (sigma 4) `\WINWORD.EXE` corpus 10 (sigma 10) `\wordpad.exe` corpus 2 (sigma 2) `\wordview.exe` corpus 2 (sigma 2)

`j` / `k`	Scroll down / up
`d` / `u`	Half-page down / up
`gg` / `G`	Top / bottom
`h` / `l`	History back / forward
`f`	Follow link (`Shift` = new tab)
`/`	Focus search
`?`	Toggle this help
`↑` / `↓`	Navigate search results
`Enter`	Open highlighted result
`Esc`	Close results / dialog

`type:`	`events` / `rules` / `providers`
`vendor:`	`sigma` / `elastic` / `splunk` / `kusto` / `chronicle` (vendor name alone also works: `sigma:`, `kql:`, `secops:`…)
`tactic:`	TA-id, slug, or name: `credential_access`, `TA0006`
`technique:`	technique or sub-technique ID: `T1003`, `T1003.001` (alias `tech:`)
`severity:`	`critical` / `high` / `medium` / `low` / `informational` (alias `sev:`)
`risk_score`	Numeric comparison on the Elastic risk score (0 to 100): `risk_score>50`, `risk_score<=20`, `risk_score=99` (alias `risk`; Elastic rules only)
`stages:`	Rules with exactly N pipeline stages
`correlation:`	`single_event` / `sequence` / `alternatives` / `alternatives_cross_log` / `all_required` / `correlated`
`with:`	Co-occurrence event-id; stacks (`with:4624 with:4769`) to require all, while a comma list in one occurrence (`with:4624,4769`) is an either-or group. Implies multi-event
`like:`	Structural neighbors of a rule slug (equivalents + subsumption stricter / broader): `like:comsvcs_lsass_memory_dump-splunk-sysmon`
`groupby:`	Entity-grouping substring match against `group_by_keys`: `groupby:user`, `groupby:host`
`uses:`	Rules whose predicate tree touches the field (any kind, any value): `uses:CommandLine`
`excludes:`	Rules with top-level `not()` clauses on the field (FP whitelists): `excludes:ParentImage`
`field:` / `value:`	Predicate search; narrows rule cards to those with a matching leaf and drives the indicator tier. Unquoted = substring, wildcards allowed (`value:mimikatz`)
`indicator:`	Shorthand for `field:F value:V`: `indicator:Image=*\powershell.exe`
`kind:`	Filter by predicate kind. Narrows rule cards to those carrying a matching predicate leaf (`vendor:elastic kind:cidr_match`) and drives the indicator tier: `contains` / `starts_with` / `ends_with` / `regex` / `cidr` / `eq` / `in` … (operator aliases `op:`/`match:`)
`has:` / `no:`	`sample`, `field`, `notes`, `refs`, `trace`, `thirdparty`, `rule`, `pattern`, `timewindow`, `threshold`, `newterms`, `sigma`/`elastic`/`splunk`/`kusto`/`chronicle`
`-op:val`	Exclude matches; works on most operators but not `type:`/`like:`/`has:`/`no:` (use `no:<flag>` to exclude a rule flag): `tactic:execution -vendor:splunk`. Standalone `-kind:`/`-field:`/`-value:` drop every rule carrying a matching predicate leaf (`type:rules -kind:is_null`)
`field:"…"` / `value:"…"`	Quoted value = anchored exact match (also allows spaces): `value:"net user"`
`a,b`	Comma = OR inside one operator (`vendor:sigma,elastic`, `severity:high,critical`); repeating a facet merges the same way. `field:`/`value:` never split (literal commas)
`vendors:` / `stage:`	Singular and plural spellings fold to the canonical operator and value: `tactics:` = `tactic:`, `type:event` = `type:events`, `correlation:sequences` = `correlation:sequence`, `has:thresholds` = `has:threshold`
`"quoted phrase"`	Exact-match a multi-word phrase (free text)

Suspicious Microsoft Office Child Process

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: `condition`

Stage 1: `selection_parent`

Stage 2: `selection_child_processes`

Stage 3: `selection_child_susp_paths`

Indicators

Keyboard shortcuts

Search operators

Suspicious Microsoft Office Child Process

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: condition

Stage 1: selection_parent

Stage 2: selection_child_processes

Stage 3: selection_child_susp_paths

Indicators

Stage 0: `condition`

Stage 1: `selection_parent`

Stage 2: `selection_child_processes`

Stage 3: `selection_child_susp_paths`