What is the SCR file format?
.scr files are Windows Screensaver executables - binary files that store executable code for desktop screensavers. A .scr is a standard Portable Executable starting with the MZ magic bytes (4D 5A) and a PE\0\0 signature, structurally identical to a regular .exe.
A screensaver is a type of utility that can generate graphics, moving images or patterns, or even sounds. A screensaver can be launched automatically after a period of inactivity or manually, depending on system desktop settings. The original purpose of screensavers was to prevent monitor phosphor burn-in and wear when idle for a longer time.
Windows passes .scr files three command-line switches: /s (run), /c (configure), and /p <HWND> (preview). Explorer's right-click menu surfaces these as Test, Configure, and Install options.
.scr files can be installed manually by copying them into %SystemRoot%\System32. A newly installed screensaver becomes available from Display Settings or a .deskthemepack theme package. Because .scr files are full Windows executables, they carry the same security risk as .exe files - always verify the source before installing an untrusted screensaver.
Security & safety
RISK: HIGHThis is the headline fact: a .scr is a fully functional Windows executable, so running one can do anything an .exe can - install malware, ransomware or a trojan. Emailing a virus as a 'screensaver' (e.g. photos.scr, invoice.scr, often zipped) is a long-running attack because Windows hides known extensions by default, making malware.scr look like a document. Safety checklist: (1) NEVER open an .scr that arrives by email/chat or from an untrusted download - treat it exactly like an unexpected .exe; (2) turn ON 'File name extensions' in Explorer's View menu so disguised files are visible; (3) to inspect a suspicious .scr safely, open it as an archive in 7-Zip or in Resource Hacker (which read it WITHOUT executing), and scan it on VirusTotal; (4) legitimate screensavers should come from a known vendor or the Microsoft Store, code-signed where possible. If folders or files suddenly appear as .scr, suspect malware and run a full antivirus scan.
Format details
in a nutshellPrograms that open SCR files
Windows3 apps
7-Zip
Open-source Right-click > 7-Zip > Open archive to INSPECT a screensaver (a PE file) and extract embedded images WITHOUT running it - useful to vet a suspicious .scr. 
Resource Hacker
Free Open the .scr to view its resources (icon, images, dialogs) without executing the code - safe way to see what's inside. 
Windows (built-in)
Built-in Right-click the .scr > Install (sets it as the active screensaver) or Test (previews it). Configure via Settings > Personalization > Lock screen > Screen saver. Only do this for files you trust. Technical details
deep spec| File structure | Windows Portable Executable (PE32 or PE32+) - same binary format as .exe and .dll files |
| Magic bytes | 4D 5A ("MZ") at offset 0; PE\0\0 signature at the offset stored in bytes 0x3C-0x3F |
| MIME type | application/x-msdownload |
| Command-line switches | /s (run full-screen), /c (open configuration dialog), /p <HWND> (render preview in Screen Saver Settings) |
| Installation path | %SystemRoot%\System32 for 64-bit screensavers; %SystemRoot%\SysWOW64 for 32-bit screensavers on 64-bit Windows |
| Windows API | Screen Saver Library (scrnsave.h / scrnsave.lib) or raw Win32 GDI/Direct3D for full-screen rendering |
| Embedded resources | Standard PE resource sections can contain icons, bitmaps, dialog boxes, string tables, and version information |
| Execution privilege | Runs in the context of the logged-in user account; no sandboxing or privilege elevation by default |
| Security marking | Downloads acquire the Mark of the Web (NTFS alternate data stream Zone.Identifier); Windows blocks execution until the file is manually unblocked |
| Configuration storage | Per-screensaver settings written to HKCU\Control Panel\Screen Saver.<ScreenSaverName> in the Windows registry |
| Idle activation | Timeout configured in Display Settings → Screen Saver → Wait; stored as ScreenSaveTimeOut (seconds) in HKCU\Control Panel\Desktop |
| Password lock integration | When "On resume, display logon screen" is enabled, dismissing the screensaver triggers the Windows credential provider |
| Released | 1992 (screensaver support in Windows 3.1) |
| Specification | learn.microsoft.com |
SCR conversions
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