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Windows New Default File Association Value Set

The following analytic detects registry changes to the default file association value. It leverages data from the Endpoint data model, specifically monitoring registry paths under "HKCR\\*\\shell\\open\\command\\*".…

Description

The following analytic detects registry changes to the default file association value. It leverages data from the Endpoint data model, specifically monitoring registry paths under "HKCR\\*\\shell\\open\\command\\*". This activity can be significant because, attackers might alter the default file associations in order to execute arbitrary scripts or payloads when a user opens a file, leading to potential code execution. If confirmed malicious, this technique can enable attackers to persist on the compromised host and execute further malicious commands, posing a severe threat to the environment.

Detection logic

Detection requirements

Platform
Windows

The rule states no platform. This is derived from the ATT&CK technique it maps to.

Log source category
sysmon_eventid_13

Known benign triggers

  • Windows and third party software will create and modify these file associations during installation or upgrades. Additional filters needs to be applied to tune environment specific false positives.

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