Detection: Windows Rename System Utilities Aspnet compiler exe LOLBAS in Non Standard Path

Description

The following analytic identifies Aspnet_Compiler.exe which is a native living off the land binary or script (LOLBAS) within the Windows operating system that may be abused by adversaries by moving it to a new directory. The list of binaries was derived from the https://lolbas-project.github.io site. The specific default filepath for the Aspnet_compiler.exe should be in "C:\Windows\Microsoft.NET\Framework".

Annotations

No annotations available.

Implementation

To successfully implement this search, you must be ingesting logs with the process name, command-line arguments, and parent processes from your endpoints. Collect endpoint data such as Sysmon or Windows Events 4688.

Known False Positives

False positives may be present and filtering may be required. Certain utilities will run from non-standard paths based on the third-party application in use.

Associated Analytic Story

• Unusual Processes

• Living Off The Land

Risk Based Analytics (RBA)

References

• https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1036.003/T1036.003.yaml

• https://attack.mitre.org/techniques/T1036/003/

• https://lolbas-project.github.io/lolbas/Binaries/Aspnet_Compiler/

Version: 5