Detect Screensaver in IBM QRadar
Adversaries may establish persistence by modifying the Windows screensaver configuration. Screensavers are programs that execute after a configurable time of user inactivity and consist of Portable Executable (PE) files with a .scr file extension. Adversaries can abuse this by modifying the SCRNSAVE.EXE registry value in HKCU\Control Panel\Desktop to point to a malicious executable that runs whenever the screen saver activates.
MITRE ATT&CK
- Tactic
- Privilege Escalation Persistence
- Technique
- T1546 Event Triggered Execution
- Sub-technique
- T1546.002 Screensaver
- Canonical reference
- https://attack.mitre.org/techniques/T1546/002/
QRadar Detection Query
SELECT
DATEFORMAT(starttime, 'YYYY-MM-dd HH:mm:ss') AS event_time,
sourceip,
username,
"TargetObject",
"Details",
"Image",
"CommandLine",
LOGSOURCENAME(logsourceid) AS log_source
FROM events
WHERE
LOGSOURCETYPEID IN (13, 14)
AND "EventID" IN (12, 13)
AND "TargetObject" ILIKE '%Control Panel%Desktop%'
AND (
"TargetObject" ILIKE '%SCRNSAVE.EXE%'
OR "TargetObject" ILIKE '%ScreenSaveActive%'
OR "TargetObject" ILIKE '%ScreenSaverIsSecure%'
OR "TargetObject" ILIKE '%ScreenSaveTimeOut%'
)
AND (
LOWER("Details") LIKE '%appdata%'
OR LOWER("Details") LIKE '%\\temp\\%'
OR LOWER("Details") LIKE '%programdata%'
OR LOWER("Details") LIKE '%\\public\\%'
OR LOWER("Details") LIKE '%powershell%'
OR LOWER("Details") LIKE '%cmd.exe%'
OR LOWER("Details") LIKE '%wscript%'
OR LOWER("Details") LIKE '%cscript%'
OR LOWER("Details") LIKE '%rundll32%'
OR (
"TargetObject" ILIKE '%SCRNSAVE.EXE%'
AND LOWER("Details") NOT LIKE '%c:\\windows\\system32\\%'
AND LOWER("Details") NOT LIKE '%c:\\windows\\syswow64\\%'
AND "Details" <> ''
)
)
LAST 24 HOURS
ORDER BY starttime DESCDetects T1546.002 screensaver persistence via QRadar by querying Sysmon registry event logs (EventID 12/13) for modifications to HKCU\Control Panel\Desktop screensaver values. Flags entries where the screensaver executable path is outside trusted system directories or where suspicious process names appear in registry data.
Data Sources
Required Tables
False Positives & Tuning
- Enterprise deployment tools writing screensaver configuration as part of standardized desktop policy rollouts
- Security baseline hardening scripts that set ScreenSaverIsSecure=1 or adjust timeout values system-wide
- Remote monitoring and management (RMM) agents temporarily modifying ScreenSaveActive to prevent lockout during maintenance windows
Other platforms for T1546.002
Testing Methodology
Validate this detection against 3 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1Set Malicious Screensaver Path in Registry
Expected signal: Sysmon Event ID 13 (Registry Value Set) for HKCU\Control Panel\Desktop\SCRNSAVE.EXE with Details=C:\Windows\System32\cmd.exe. Additional Event ID 13 records for ScreenSaveActive and ScreenSaveTimeOut. Security Event ID 4657 if registry auditing is enabled.
- Test 2Disable Screensaver Lock Screen for Silent Execution
Expected signal: Sysmon Event ID 13: TargetObject HKCU\Control Panel\Desktop\ScreenSaverIsSecure, Details=0. This should be correlated with concurrent SCRNSAVE.EXE changes.
- Test 3Deploy Fake Screensaver via AppData
Expected signal: Sysmon Event ID 11 (File Created): malicious.scr in AppData path. Sysmon Event ID 13: SCRNSAVE.EXE value set to AppData path. Both the file creation and registry modification events fire. The AppData path in the registry value is the primary detection trigger.
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