Suspicious parentprocess relationship - Office child processes.

Original query, unchanged.

let browsers = dynamic(["iexplore.exe", "chrome.exe", "firefox.exe", "msedge.exe"]); // Customize this list for your environment.
let officeApps = dynamic(["winword.exe", "excel.exe", "powerpnt.exe"]); // Consider adding other Office applications such as Publisher, Visio and Access. 
// This is an allow-list of the most common child processes. This is a quick and dirty solution. Consider allow-listing the full process path instead of file name.
// Also, make this list as short as possible. Remove anything from this list if it doesn't occur in your organization. 
let allowList = dynamic(["MSOSYNC.exe", "splwow64.exe", "csc.exe", "outlook.exe", "AcroRd32.exe", "Acrobat.exe", "explorer.exe", "DW20.exe", 
"Microsoft.Mashup.Container.Loader.exe", "Microsoft.Mashup.Container.NetFX40.exe", "WerFault.exe", "CLVIEW.exe"]); 
DeviceProcessEvents
| where InitiatingProcessParentFileName in~ (browsers) and InitiatingProcessFileName in~ (officeApps) and 
FileName !in~ (officeApps) and FileName !in~ (browsers) and FileName !in~ (allowList)
| project-rename ProcessStart_Timestamp = Timestamp