ATT&CK coverage › Technique

Office Application Startup: Add-ins T1137.006

Adversaries may abuse Microsoft Office add-ins to obtain persistence on a compromised system. Office add-ins can be used to add functionality to Office programs. There are different types of add-ins that can be used by the various Office products; including Word/Excel add-in Libraries (WLL/XLL), VBA add-ins, Office Component Object Model (COM) add-ins, automation add-ins, VBA Editor (VBE), Visual Studio Tools for Office (VSTO) add-ins, and Outlook add-ins.

Events covered

3 catalog events are tagged with this technique by at least one rule.

ProviderEvent IDTitle
Sysmon11FileCreate
Sysmon13RegistryEvent (Value Set)
PowerShell4104Creating Scriptblock text (MessageNumber of MessageTotal).

Authoring guide

Patterns shared across the 4 rules above: which fields they filter on, what specific values they look for, and what they exclude. Field names are normalized across vendors so Sigma's Image, Elastic's process.name, and Splunk's process_name collapse into one row. Each rule contributes at most once per row.

Fields filtered most (5 distinct)

The fields most rules look at when detecting this technique. The How column shows the operators authors use (eq, wildcard, regex_match, match) and how often each appears. Sample values are concrete examples to start from, not an exhaustive list.

FieldRulesHowSample values
TargetObject2match 2, ends_with 1\Excel\Options, Software\Microsoft\Office\, \Software\Microsoft\Office\Excel\Addins\, \Microsoft\Office\Outlook\Addins\Avast.AsOutExt\, \Software\Microsoft\Office\Word\Addins\
ScriptBlockText1match 1.RegisterXLL, -ComObject , new-object
Details1ends_with 1, starts_with 1/R , .xll
TargetFilename1ends_with 1, match 1.wll, \Microsoft\Word\Startup\, .ppam
Image1ends_with 1, eq 1, starts_with 1C:\Program Files (x86)\Microsoft..., C:\Windows\System32\regsvr32.exe, \visio.exe

Top indicator values (48 distinct)

Specific (field, operator, value) combinations the rules check for, ranked by how many rules under this technique use each one. The Corpus reach column counts how many rules across the entire catalog (any technique) check the same combination. High numbers point to widely-used indicators that are likely noisy on their own; combine them with another condition for useful signal. Blank means the combination is specific to rules under this technique.

FieldKindValueRules (here)Corpus reach
ScriptBlockTextmatch.application1
ScriptBlockTextmatch.RegisterXLL1
ScriptBlockTextmatchnew-object 1
ScriptBlockTextmatch-ComObject 1
Detailsends_with.xll1
TargetObjectmatchSoftware\Microsoft\Office\12
TargetObjectends_with\Excel\Options1
Detailsstarts_with/R 1
TargetFilenamematch\Microsoft\Word\Startup\1
TargetFilenameends_with.xll12
TargetFilenamematchMicrosoft\Excel\XLSTART\1
TargetFilenameends_with.xlam1
TargetFilenamematch\Microsoft\Excel\Startup\1
TargetFilenameends_with.ppam1
TargetFilenameends_with.xla1
TargetFilenameends_with.wll12
TargetFilenamematch\Microsoft\Addins\1
TargetObjectmatch\Software\Microsoft\Office\Excel\Addins\1
TargetObjectmatch\Microsoft\Office\Outlook\Addins\Antivirus.AsOutExt\12
Imageends_with\visio.exe13

Rules under this technique

Every rule in the catalog tagged with this technique, grouped by vendor. Click a rule title for its full predicates, exclusions, and indicators.

Sigma 4 rules