What is seclogon.dll?

Seclogon.dll is a Windows DLL file. DLL is the abbreviation for Dynamic Link Library. DLL files are needed by programs or web browser extensions, because they contain program code, data, and resources. The following information can help you determine if seclogon.dll is a Windows system file or if it belongs to an application that you can trust.

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Seclogon.dll file information

The process known as Secondary Logon Service DLL belongs to software Microsoft Windows Operating System by Microsoft (

Description: Seclogon.dll is not essential for the Windows OS and causes relatively few problems. The file seclogon.dll is located in the C:\Windows\System32 folder. Known file sizes on Windows 10/8/7/XP are 18,944 bytes (92% of all occurrences), 21,504 bytes, 20,992 bytes or 19,968 bytes. 
The service can be started or stopped from Services in the Control Panel or by other programs. The program has no visible window. The file is a trustworthy file from Microsoft. The seclogon.dll file is not a Windows system file. Seclogon.dll is able to manipulate other programs. Therefore the technical security rating is 2% dangerous, however you should also read the user reviews.

Recommended: Identify seclogon.dll related errors

Important: Some malware disguises itself as seclogon.dll, particularly when not located in the C:\Windows\System32 folder. Therefore, you should check the seclogon.dll process on your PC to see if it is a threat. We recommend Security Task Manager for verifying your computer's security. This was one of the Top Download Picks of The Washington Post and PC World.


User Comments

My C:\Windows\System32\seclogon.dll on Windows 7 64-bit is 30,720 bytes. Is that likely to mean it's infected?
  John Vincent  

One user is not sure about it.

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Best practices for resolving seclogon issues

A clean and tidy computer is the key requirement for avoiding problems with seclogon. This means running a scan for malware, cleaning your hard drive using cleanmgr and sfc /scannow, uninstalling programs that you no longer need, checking for Autostart programs (using msconfig) and enabling Windows' Automatic Update. Always remember to perform periodic backups, or at least to set restore points.

Should you experience an actual problem, try to recall the last thing you did, or the last thing you installed before the problem appeared for the first time. Use the resmon command to identify the processes that are causing your problem. Even for serious problems, rather than reinstalling Windows, you are better off repairing of your installation or, for Windows 8 and later versions, executing the DISM.exe /Online /Cleanup-image /Restorehealth command. This allows you to repair the operating system without losing data.

To help you analyze the seclogon.dll process on your computer, the following programs have proven to be helpful: Security Task Manager displays all running Windows tasks, including embedded hidden processes, such as keyboard and browser monitoring or Autostart entries. A unique security risk rating indicates the likelihood of the process being potential spyware, malware or a Trojan. Malwarebytes Anti-Malware detects and removes sleeping spyware, adware, Trojans, keyloggers, malware and trackers from your hard drive.

Other processes

seclogon.dll [all]