408. Adversaries Disable Updates for Compromised Systems

Hello everyone!

Today we'll look at how threat actors interfere with updates on compromised systems as part of the Disable or Modify Tools (T1685) technique.

This time, our focus is on macOS. Let's open the report on XCSSET activity and scroll to the "Impairing Defenses" section. As you can see, the threat actor uses the following commands to disable specific Apple security update mechanisms:

defaults write /Library/Preferences/com.apple.SoftwareUpdate.plist ConfigDataInstall -bool false

defaults write /Library/Preferences/com.apple.SoftwareUpdate.plist AllowRapidSecurityResponses -bool false

The first command disables the delivery of security data updates for XProtect, Gatekeeper, and other Apple security components. The second disables the installation of Rapid Security Responses (RSR).

To detect this behavior, we can hunt for modifications to the com.apple.SoftwareUpdate.plist file performed through the defaults utility:

event_type: "processcreatemac"

AND

proc_file_path: "defaults"

AND

cmdline: "com.apple.SoftwareUpdate.plist"

See you soon!

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