LogiLDA.dll: Logitech's Download Assistant or a file using its name?

What LogiLDA.dll does

LogiLDA.dll is the Logitech Download Assistant. Logitech's device software installs it in C:\Windows\System32 and adds a Startup entry that starts it at every sign-in through rundll32.exe, the Windows tool that runs code stored in a DLL. Its job is to look for newer Logitech software. Your mouse, keyboard and their settings do not depend on it.

Most people meet the file through a box at sign-in that says Windows had a problem starting it, usually after a Windows update or after Logitech software was removed while its Startup entry stayed behind. That box is a leftover, not a sign of infection. The security question is a different one: whether a LogiLDA.dll on your PC is Logitech's file at all, since a DLL that starts with Windows from a familiar vendor name is something malware authors like to imitate.

About .dll files. A .dll file is a library: it cannot run on its own and is loaded into a program's process. It does not appear in Task Manager under its own name; Process Explorer shows which process loaded it.

How to check a copy of LogiLDA.dll

Four things decide it: where the file is, what it says about itself, who signed it, and what starts it. A library run by rundll32 never appears in Task Manager under its own name, so use these checks.

1. List every copy and where it sits. One copy in C:\Windows\System32 is normal on a PC with Logitech software. A LogiLDA.dll in Downloads, Temp, AppData, ProgramData or a program folder is not where Logitech's installer puts it.

   Get-ChildItem -Path C:\ -Filter LogiLDA.dll -Recurse -ErrorAction SilentlyContinue | Select-Object FullName, Length, LastWriteTime

2. Read the version resource. Logitech's file reports Logitech, Inc. as the company and Logitech Download Assistant as the description. Empty fields or another company point away from Logitech, though a careful fake can copy the text, so this check alone does not clear a file.

   (Get-Item "C:\Windows\System32\LogiLDA.dll").VersionInfo | Format-List CompanyName, FileDescription, FileVersion

3. Check the digital signature. Status Valid with a Logitech signer means an unmodified Logitech file. NotSigned, HashMismatch or another signer means it is not Logitech's file as shipped. Text fields can be copied; a valid signature cannot.

   Get-AuthenticodeSignature "C:\Windows\System32\LogiLDA.dll" | Format-List Status, SignerCertificate

4. See what starts it. The genuine Startup entry is named Logitech Download Assistant and runs rundll32 with C:\Windows\System32\LogiLDA.dll. Any entry or scheduled task that runs a LogiLDA.dll from another folder, or under another name, was not made by Logitech's installer.

   Get-CimInstance Win32_StartupCommand | Where-Object Command -match 'LogiLDA' | Format-List Name, Command, Location

5. Compare the size and checksum. Use the file check on this page. The Logitech copies in the catalogue are about 3.8 MB. A match identifies a known copy; no match is not proof of a fake, because not every Logitech build is listed. The signature check above is the deciding one.

A valid Logitech signature clears that one file. It does not clear other entries in Startup apps or Task Scheduler, so look at those too if the PC behaves oddly.

Do you need LogiLDA.dll?

No program needs it except its own Startup entry. Keep it if you use Logitech software and want automatic update checks; otherwise you can turn it off. A copy that failed the checks above is a different matter: remove it and scan.

1. Turn off the Startup entry if you do not want it. Open Task Manager, Startup apps, right-click Logitech Download Assistant and choose Disable. The device keeps working, and you can turn it back on at any time.
2. Uninstall Logitech software you no longer use. Open Settings, Apps, Installed apps, find the Logitech entries and uninstall them. That removes the software that put LogiLDA.dll in System32.
3. Run a Microsoft Defender full scan for a copy that failed the checks. Open Windows Security, Virus and threat protection, Scan options, Full scan. Quarantine what it finds and look at Protection history for anything found in Downloads, Temp or AppData.
4. Run the offline scan. Some malware hides while Windows runs. The offline scan restarts the PC and scans before Windows starts. It takes about 15 minutes.

   Start-MpWDOScan

5. Clean up what starts with Windows. After the scan, open Task Manager, Startup apps, and Task Scheduler. Disable and remove entries that run a program or DLL from AppData, ProgramData or Temp that you do not recognise.

Warning signs

Known versions of logilda.dll

A public DLL catalogue lists 3 versions of logilda.dll, from 1.10.77.0 to 1.10.77.0, by Logitech, Inc.. Its copies are uploaded by users and not verified, so a checksum match identifies the version, while the digital signature tells you whether the file is genuine. Even a genuine file clears only the file, not the folder: attackers ship genuine libraries next to a program they abuse, so where the copy sits still decides whether it is safe.

Every version with its checksums, and how to fix logilda.dll errors on uGetFix

Questions people ask