Potential Persistence Via Visual Studio Tools for Office

Status: test
Severity: medium
Log source: product windows, category registry_set
Author: Bhabesh Raj
Source: github.com/SigmaHQ/sigma

Detects persistence via Visual Studio Tools for Office (VSTO) add-ins in Office applications.

MITRE ATT&CK coverage

Tactic	Techniques
Persistence	`T1137.006` Office Application Startup: Add-ins

Event coverage

Provider	Event	Title
Sysmon	Event ID 13	RegistryEvent (Value Set)

Rule body yaml

title: Potential Persistence Via Visual Studio Tools for Office
id: 9d15044a-7cfe-4d23-8085-6ebc11df7685
status: test
description: Detects persistence via Visual Studio Tools for Office (VSTO) add-ins in Office applications.
references:
    - https://twitter.com/_vivami/status/1347925307643355138
    - https://vanmieghem.io/stealth-outlook-persistence/
author: Bhabesh Raj
date: 2021-01-10
modified: 2026-01-09
tags:
    - attack.t1137.006
    - attack.persistence
logsource:
    category: registry_set
    product: windows
detection:
    selection:
        TargetObject|contains:
            - '\Software\Microsoft\Office\Outlook\Addins\'
            - '\Software\Microsoft\Office\Word\Addins\'
            - '\Software\Microsoft\Office\Excel\Addins\'
            - '\Software\Microsoft\Office\Powerpoint\Addins\'
            - '\Software\Microsoft\VSTO\Security\Inclusion\'
    filter_main_system:
        Image:
            - 'C:\Windows\System32\msiexec.exe'
            - 'C:\Windows\SysWOW64\msiexec.exe'
            - 'C:\Windows\System32\regsvr32.exe'
            - 'C:\Windows\SysWOW64\regsvr32.exe' # e.g. default Evernote installation
    filter_main_office_click_to_run:
        Image|startswith:
            - 'C:\Program Files\Common Files (x86)\Microsoft Shared\ClickToRun\'
            - 'C:\Program Files\Common Files\Microsoft Shared\ClickToRun\'
        Image|endswith: '\OfficeClickToRun.exe'
    filter_main_integrator:
        Image:
            - 'C:\Program Files (x86)\Microsoft Office\root\integration\integrator.exe'
            - 'C:\Program Files\Microsoft Office\root\integration\integrator.exe'
    filter_main_office_apps:
        Image|startswith:
            - 'C:\Program Files\Microsoft Office\OFFICE'
            - 'C:\Program Files (x86)\Microsoft Office\OFFICE'
            - 'C:\Program Files\Microsoft Office\Root\OFFICE'
            - 'C:\Program Files (x86)\Microsoft Office\Root\OFFICE'
            - 'C:\PROGRA~2\MICROS~2\Office'
        Image|endswith:
            - '\excel.exe'
            - '\Integrator.exe'
            - '\OneNote.exe'
            - '\outlook.exe'
            - '\powerpnt.exe'
            - '\Teams.exe'
            - '\visio.exe'
            - '\winword.exe'
    filter_main_vsto:
        Image|startswith:
            - 'C:\Program Files\Common Files\Microsoft Shared\VSTO\'
            - 'C:\Program Files (x86)\Microsoft Shared\VSTO\'
        Image|endswith: '\VSTOInstaller.exe'
    filter_optional_avg:
        Image:
            - 'C:\Program Files\AVG\Antivirus\RegSvr.exe'
            - 'C:\Program Files (x86)\AVG\Antivirus\RegSvr.exe'
        TargetObject|contains: '\Microsoft\Office\Outlook\Addins\Antivirus.AsOutExt\'
    filter_optional_avast:
        Image:
            - 'C:\Program Files\Avast Software\Avast\RegSvr.exe'
            - 'C:\Program Files (x86)\Avast Software\Avast\RegSvr.exe'
        TargetObject|contains: '\Microsoft\Office\Outlook\Addins\Avast.AsOutExt\'
    condition: selection and not 1 of filter_main_* and not 1 of filter_optional_*
falsepositives:
    - Legitimate Addin Installation
level: medium

Stages and Predicates

Stage 0: `condition`

selection and not 1 of filter_main_* and not 1 of filter_optional_*

Stage 1: `selection`

selection:
    TargetObject|contains:
        - '\Software\Microsoft\Office\Outlook\Addins\'
        - '\Software\Microsoft\Office\Word\Addins\'
        - '\Software\Microsoft\Office\Excel\Addins\'
        - '\Software\Microsoft\Office\Powerpoint\Addins\'
        - '\Software\Microsoft\VSTO\Security\Inclusion\'

Stage 2: `not filter_main_*`

filter_main_system:
    Image:
        - 'C:\Windows\System32\msiexec.exe'
        - 'C:\Windows\SysWOW64\msiexec.exe'
        - 'C:\Windows\System32\regsvr32.exe'
        - 'C:\Windows\SysWOW64\regsvr32.exe'
filter_main_office_click_to_run:
    Image|startswith:
        - 'C:\Program Files\Common Files (x86)\Microsoft Shared\ClickToRun\'
        - 'C:\Program Files\Common Files\Microsoft Shared\ClickToRun\'
    Image|endswith: '\OfficeClickToRun.exe'
filter_main_integrator:
    Image:
        - 'C:\Program Files (x86)\Microsoft Office\root\integration\integrator.exe'
        - 'C:\Program Files\Microsoft Office\root\integration\integrator.exe'
filter_main_office_apps:
    Image|startswith:
        - 'C:\Program Files\Microsoft Office\OFFICE'
        - 'C:\Program Files (x86)\Microsoft Office\OFFICE'
        - 'C:\Program Files\Microsoft Office\Root\OFFICE'
        - 'C:\Program Files (x86)\Microsoft Office\Root\OFFICE'
        - 'C:\PROGRA~2\MICROS~2\Office'
    Image|endswith:
        - '\excel.exe'
        - '\Integrator.exe'
        - '\OneNote.exe'
        - '\outlook.exe'
        - '\powerpnt.exe'
        - '\Teams.exe'
        - '\visio.exe'
        - '\winword.exe'
filter_main_vsto:
    Image|startswith:
        - 'C:\Program Files\Common Files\Microsoft Shared\VSTO\'
        - 'C:\Program Files (x86)\Microsoft Shared\VSTO\'
    Image|endswith: '\VSTOInstaller.exe'

Stage 3: `not filter_optional_*`

filter_optional_avg:
    Image:
        - 'C:\Program Files\AVG\Antivirus\RegSvr.exe'
        - 'C:\Program Files (x86)\AVG\Antivirus\RegSvr.exe'
    TargetObject|contains: '\Microsoft\Office\Outlook\Addins\Antivirus.AsOutExt\'
filter_optional_avast:
    Image:
        - 'C:\Program Files\Avast Software\Avast\RegSvr.exe'
        - 'C:\Program Files (x86)\Avast Software\Avast\RegSvr.exe'
    TargetObject|contains: '\Microsoft\Office\Outlook\Addins\Avast.AsOutExt\'

Exclusions

Top-level NOT(...) conjuncts: predicates this rule actively suppresses.

Field	Kind	Excluded values
`Image`	ends_with	`\Integrator.exe`
`Image`	ends_with	`\OneNote.exe`
`Image`	ends_with	`\Teams.exe`
`Image`	ends_with	`\excel.exe`
`Image`	ends_with	`\outlook.exe`
`Image`	ends_with	`\powerpnt.exe`
`Image`	ends_with	`\visio.exe`
`Image`	ends_with	`\winword.exe`
`Image`	starts_with	`C:\PROGRA~2\MICROS~2\Office`
`Image`	starts_with	`C:\Program Files (x86)\Microsoft Office\OFFICE`
`Image`	starts_with	`C:\Program Files (x86)\Microsoft Office\Root\OFFICE`
`Image`	starts_with	`C:\Program Files\Microsoft Office\OFFICE`
`Image`	starts_with	`C:\Program Files\Microsoft Office\Root\OFFICE`
`Image`	starts_with	`C:\Program Files (x86)\Microsoft Shared\VSTO\`
`Image`	starts_with	`C:\Program Files\Common Files\Microsoft Shared\VSTO\`
`Image`	ends_with	`\VSTOInstaller.exe`
`Image`	starts_with	`C:\Program Files\Common Files (x86)\Microsoft Shared\ClickToRun\`
`Image`	starts_with	`C:\Program Files\Common Files\Microsoft Shared\ClickToRun\`
`Image`	ends_with	`\OfficeClickToRun.exe`
`Image`	eq	`C:\Program Files (x86)\Microsoft Office\root\integration\integrator.exe`
`Image`	eq	`C:\Program Files\Microsoft Office\root\integration\integrator.exe`
`Image`	eq	`C:\Windows\SysWOW64\msiexec.exe`
`Image`	eq	`C:\Windows\SysWOW64\regsvr32.exe`
`Image`	eq	`C:\Windows\System32\msiexec.exe`
`Image`	eq	`C:\Windows\System32\regsvr32.exe`
`Image`	eq	`C:\Program Files (x86)\AVG\Antivirus\RegSvr.exe`
`Image`	eq	`C:\Program Files\AVG\Antivirus\RegSvr.exe`
`TargetObject`	match	`\Microsoft\Office\Outlook\Addins\Antivirus.AsOutExt\`
`Image`	eq	`C:\Program Files (x86)\Avast Software\Avast\RegSvr.exe`
`Image`	eq	`C:\Program Files\Avast Software\Avast\RegSvr.exe`
`TargetObject`	match	`\Microsoft\Office\Outlook\Addins\Avast.AsOutExt\`

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
`TargetObject`	match	`\Software\Microsoft\Office\Excel\Addins\` `\Software\Microsoft\Office\Outlook\Addins\` `\Software\Microsoft\Office\Powerpoint\Addins\` `\Software\Microsoft\Office\Word\Addins\` `\Software\Microsoft\VSTO\Security\Inclusion\`

`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)

Potential Persistence Via Visual Studio Tools for Office

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: `condition`

Stage 1: `selection`

Stage 2: `not filter_main_*`

Stage 3: `not filter_optional_*`

Exclusions

Indicators

Keyboard shortcuts

Search operators

Potential Persistence Via Visual Studio Tools for Office

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: condition

Stage 1: selection

Stage 2: not filter_main_*

Stage 3: not filter_optional_*

Exclusions

Indicators

Stage 0: `condition`

Stage 1: `selection`

Stage 2: `not filter_main_*`

Stage 3: `not filter_optional_*`