Event Triggered Execution: Screensaver (T1546.002)
Tactics: Privilege Escalation, Persistence · Platforms: Windows
The interactive view maps 1 detection strategy, 2 mitigations, 1 software entry to this technique, alongside D3FEND countermeasures and data-component coverage.
Sub-technique of Event Triggered Execution (T1546).
Overview
Adversaries may establish persistence by executing malicious content triggered by user inactivity. Screensavers are programs that execute after a configurable time of user inactivity and consist of Portable Executable (PE) files with a .scr file extension. The Windows screensaver application scrnsave.scr is located in C:\Windows\System32\, and C:\Windows\sysWOW64\ on 64-bit Windows systems, along with screensavers included with base Windows installations.
The following screensaver settings are stored in the Registry (HKCU\Control Panel\Desktop\) and could be manipulated to achieve persistence:
* SCRNSAVE.exe - set to malicious PE path * ScreenSaveActive - set to '1' to enable the screensaver * ScreenSaverIsSecure - set to '0' to not require a password to unlock * ScreenSaveTimeout - sets user inactivity timeout before screensaver is executed
Adversaries can use screensaver settings to maintain persistence by setting the screensaver to run malware after a certain timeframe of user inactivity.