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ASR Bypassing Writing Executable Content

Description

The query checks for any file which has been created/written by an Office application and shortly after renamed to one of the deny-listed "executable extensions" which are text files. (e.g. ps1, .js, .vbs).
Rule type
Scheduled
Version
1.0.0
Declared status
Available
Query frequency
1h
Query period
1h
Trigger
gt 0

Declared MITRE coverage

Declared sources

Metadata from the source file. No dependencies inferred from KQL.

Connectors

Data types

KQL query

Original query, unchanged.

let timeframe = 1d;
let executableExtensions = dynamic([".js", ".hta", ".lnk", ".application", ".vb", ".vba", ".vbs", ".ps", ".ps1", ".bat", ".cmd"]);
DeviceFileEvents
| where Timestamp >= ago(timeframe)
| where InitiatingProcessFileName in~ ("winword.exe", "excel.exe", "outlook.exe", "powerpnt.exe")
| where ActionType == "FileRenamed"
// The mv-apply is less performance compared to doing a full written out !endswith. We kept the mv-apply since We don't hit any limits and get more readable/maintainable code.
| mv-apply ext=executableExtensions to typeof(string) on
(
    where PreviousFileName !endswith ext and FileName endswith ext
)
| project-reorder PreviousFileName, FileName
// Begin allow-list.
// End allow-list.

Declared entities

HostAccountProcess

Related content

Links established from declared identifiers and solution manifests.

Source provenance

GitHub

Displayed values come from files in Azure/Azure-Sentinel. They describe the published template, not your workspace configuration.

Source identifier
efe4efef-5ca7-4b51-a53e-0e96492ce97a
Additional source files 2Solutions/FalconFriday/Analytic Rules/ASRBypassingWritingExecutableContent.yamlsource ↗Solutions/FalconFriday/Data/Solution_FalconFriday.jsonsolution-membership ↗
GSTEP / CATALOG TRACKING

Added to catalog : 16 Sept 2026 · 05:49 UTC
Last change observed : 16 Sept 2026 · 05:49 UTC

GSTEP sync dates, separate from the source content’s publication dates.