How Delete A Windows 7 dll File (In System32 Folder) By C# Language

Question

Sometimes I need to delete or replace a dll file in system32 folder of windows 7.
The code below always has Permission Denied Error :

            if (File.Exists(@"C:\Windows\system32\mydll.dll"))
            {
                fileInfo.IsReadOnly = false;
                File.Delete(@"C:\Windows\system32\mydll.dll");
            }

How can I bypass this error and replace a file in system32 folder?

You either need administrator privileges, right click the program and select "Run as Administrator"/edit the app manifest to prompt for it, or your account does not have permission to make change to the system folder. If the DLL is loaded into memory I don't know if you can delete it. — 0_______0, Sep 08 '12 at 20:56
@0_______0 thanks for the comment. but i am administrator... problem is still there. — SilverLight, Sep 08 '12 at 20:59
By default I don't think you can delete/edit any system files without changing the permissions. Programmer's answer will take ownership of it and grant the permission to delete it. — 0_______0, Sep 08 '12 at 21:03
What happens if you try deleting the file manually, or through command prompt? Wondering if Windows give you the same problem. I also wonder why you've trying to do this. If it's a 'system' file, I'd highly advise deleting on a reboot task. — Arran, Sep 08 '12 at 23:19

Elmo · Answer 1 · 2012-09-13T16:23:50.060

2

if (File.Exists(@"C:\Windows\System32\mydll.dll"))
{
    new Process() { StartInfo = new ProcessStartInfo("cmd.exe", @"/k takeown /f C:\Windows\System32\mydll.dll && icacls C:\Windows\System32\mydll.dll /grant %username%:F") }.Start();
    File.Delete(@"C:\Windows\System32\mydll.dll");
}

Note that you can't delete a system DLL like shell32.dll even after taking ownership but you can rename or move it.

edited Sep 13 '12 at 16:23

answered Sep 08 '12 at 20:58

Elmo

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thanks for the edit and comment. but i don't know why i always have an exception (can not find file) by your example? (we should put a @ sign befire "CMD..., am i right?) – SilverLight Sep 08 '12 at 21:18

score 2 · Accepted Answer · edited May 23 '17 at 10:28

2

A user doesn't have sufficient rights to delete files from c:\windows\system32 on Windows Vista and up. Even when logged-on using an administrator account. UAC puts a stop to it. You must ask for elevation to let the user know that you are about to tinker with the private parts. That requires embedding a manifest in your program to trigger the UAC prompt. This answer shows you how.

edited May 23 '17 at 10:28

Community

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answered Sep 09 '12 at 10:09

Hans Passant

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How Delete A Windows 7 dll File (In System32 Folder) By C# Language

2 Answers2