T1546.002SubTechniqueprivilege-escalationpersistenceagent-callable

T1546.002Screensaver

Sub-technique of T1546

Platforms: Windows

ATT&CK version: 14.1

What it is

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.(Citation: Wikipedia Screensaver) The Windows screensaver application scrnsave.scr is located in <code>C:\Windows\System32\</code>, and <code>C:\Windows\sysWOW64\</code> on 64-bit Windows systems, along with screensavers included with base Windows installations. The following screensaver settings are stored in the Registry (<code>HKCU\Control Panel\Desktop\</code>) and could be manipulated to achieve persistence: * <code>SCRNSAVE.exe</code> - set to malicious PE path * <code>ScreenSaveActive</code> - set to '1' to enable the screensaver * <code>ScreenSaverIsSecure</code> - set to '0' to not require a password to unlock * <code>ScreenSaveTimeout</code> - 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.(Citation: ESET Gazer Aug 2017)

ATT&CK tactics· 2

Privilege EscalationPersistence

References

  1. https://attack.mitre.org/techniques/T1546/002
  2. https://www.welivesecurity.com/wp-content/uploads/2017/08/eset-gazer.pdf
  3. https://en.wikipedia.org/wiki/Screensaver
Sourced from MITRE ATT&CK Enterprise v14.1. Curated and contextualized for EU compliance use cases by Adam Lundqvist, Founder at SQUR.