Suspicious Execution via Microsoft Office Add-Ins

Last updated 9 months ago on 2025-03-20
Created 3 years ago on 2023-03-20

About

Identifies execution of common Microsoft Office applications to launch an Office Add-In from a suspicious path or with an unusual parent process. This may indicate an attempt to get initial access via a malicious phishing MS Office Add-In.
Tags
Domain: EndpointOS: WindowsUse Case: Threat DetectionTactic: Initial AccessTactic: PersistenceData Source: Elastic EndgameData Source: Elastic DefendData Source: SysmonData Source: Microsoft Defender for EndpointData Source: SentinelOneLanguage: eql
Severity
medium
Risk Score
47
MITRE ATT&CK™

Initial Access (TA0001)(external, opens in a new tab or window)

Persistence (TA0003)(external, opens in a new tab or window)

License
Elastic License v2(external, opens in a new tab or window)

Definition

Rule Type
Event Correlation Rule
Integration Pack
Prebuilt Security Detection Rules
Index Patterns
winlogbeat-*logs-endpoint.events.process-*logs-windows.sysmon_operational-*endgame-*logs-m365_defender.event-*logs-sentinel_one_cloud_funnel.*
Related Integrations

endpoint(external, opens in a new tab or window)

windows(external, opens in a new tab or window)

m365_defender(external, opens in a new tab or window)

sentinel_one_cloud_funnel(external, opens in a new tab or window)

Query
text code block:
process where host.os.type == "windows" and event.type == "start" and process.name : ("WINWORD.EXE", "EXCEL.EXE", "POWERPNT.EXE", "MSACCESS.EXE", "VSTOInstaller.exe") and process.args regex~ """.+\.(wll|xll|ppa|ppam|xla|xlam|vsto)""" and /* Office Add-In from suspicious paths */ (process.args : ("?:\\Users\\*\\Temp\\7z*", "?:\\Users\\*\\Temp\\Rar$*", "?:\\Users\\*\\Temp\\Temp?_*", "?:\\Users\\*\\Temp\\BNZ.*", "?:\\Users\\*\\Downloads\\*", "?:\\Users\\*\\AppData\\Roaming\\*", "?:\\Users\\Public\\*", "?:\\ProgramData\\*", "?:\\Windows\\Temp\\*", "\\Device\\*", "http*") or process.parent.name : ("explorer.exe", "OpenWith.exe") or /* Office Add-In from suspicious parent */ process.parent.name : ("cmd.exe", "powershell.exe")) and /* False Positives */ not (process.args : "*.vsto" and process.parent.executable : ("?:\\Program Files\\Logitech\\LogiOptions\\PlugInInstallerUtility*.exe", "?:\\ProgramData\\Logishrd\\LogiOptions\\Plugins\\VSTO\\*\\VSTOInstaller.exe", "?:\\Program Files\\Logitech\\LogiOptions\\PlugInInstallerUtility.exe", "?:\\Program Files\\LogiOptionsPlus\\PlugInInstallerUtility*.exe", "?:\\ProgramData\\Logishrd\\LogiOptionsPlus\\Plugins\\VSTO\\*\\VSTOInstaller.exe", "?:\\Program Files\\Common Files\\microsoft shared\\VSTO\\*\\VSTOInstaller.exe")) and not (process.args : "/Uninstall" and process.name : "VSTOInstaller.exe") and not (process.parent.name : "rundll32.exe" and process.parent.args : "?:\\WINDOWS\\Installer\\MSI*.tmp,zzzzInvokeManagedCustomActionOutOfProc") and not (process.name : "VSTOInstaller.exe" and process.args : "https://dl.getsidekick.com/outlook/vsto/Sidekick.vsto")

Install detection rules in Elastic Security

Detect Suspicious Execution via Microsoft Office Add-Ins in the Elastic Security detection engine by installing this rule into your Elastic Stack.

To setup this rule, check out the installation guide for Prebuilt Security Detection Rules(external, opens in a new tab or window).