CODEWITHSUNDEEP
c#delphiwinapi
mohamad zandi
mohamad zandi

Reputation: 11

Why result from WMI is different in standard mode and administrator user in Windows 7?

I want to protect my application. So I read hard drive serial number and compare. The application has good result in administrator user mode but it has bad result in standard user mode.

I wrote my application with C#. But for reading hard drive serial number I used a dll file that I wrote in Delphi.

hDevice := CreateFile( '\\.\PhysicalDrive0:', GENERIC_READ or GENERIC_WRITE ,
        FILE_SHARE_READ or FILE_SHARE_WRITE , nil, OPEN_EXISTING, 0, 0 );

I try using NET so I used WMI class Win32_DiskDrive but this method has bad results in standard user mode too.

private string getserial()
{
    string SerialNumber = "";
    string dataForSerial = string.Empty;
    ManagementObjectSearcher Finder = new ManagementObjectSearcher("Select * from Win32_OperatingSystem");
    string Name = "";

    foreach (ManagementObject OS in Finder.Get()) Name = OS["Name"].ToString();

    // Name = "Microsoft Windows XP Professional|C:\WINDOWS|\Device\Harddisk0\Partition1" 

    int ind = Name.IndexOf("Harddisk") + 8;
    int HardIndex = Convert.ToInt16(Name.Substring(ind, 1));
    Finder = new ManagementObjectSearcher("SELECT * FROM Win32_DiskDrive WHERE Index=" + HardIndex);
    foreach (ManagementObject HardDisks in Finder.Get())
        foreach (ManagementObject HardDisk in HardDisks.GetRelated("Win32_PhysicalMedia"))
            SerialNumber = HardDisk["SerialNumber"].ToString();

    // SerialNumber = dataForSerial;

    return SerialNumber;
}

In standard user mode:

  1. In case of the Delphi dll it throws an access denied error
  2. In case of the WMI the output is different in standard user vs administrator user.

Note: this problem (NO.2) is only in Windows 7.

Upvotes: 0

Views: 1526

Answers (2)

Strive Sun
Strive Sun

Reputation: 6289

Please see this Link. Results are varying depending on Windows version, on whether the code is run as admin or not, and whether the Win32_PhysicalMedia class is used or the Win32_DiskDrive class. Seems pretty unreliable, you may have to write your own abstraction layer to handle it yourself, as described in these forum posts.

I tried it myself and found I got two different serial numbers depending on admin vs normal and Win32_PhysicalMedia vs Win32_DiskDrive:

VB38bb50ab-0de50c12

and

42563833626230356261302d6564303531632032

Notice that the second string is actually a hex-encoded and byte-reversed version of the first string!

Upvotes: 1

Olaf Hess
Olaf Hess

Reputation: 1483

Please use the following code when calling CreateFile to access the physical disk. It works without admin rights and allows one to read the drive's properties:

hDisk := CreateFile ('\\.\PHYSICALDRIVE0', 0, FILE_SHARE_WRITE, NIL, OPEN_EXISTING,
                     FILE_ATTRIBUTE_NORMAL or FILE_FLAG_NO_BUFFERING, 0);

Please also take note that the name of the drive passed as the first parameter to CreateFile does not include a colon ":" at the end.

Upvotes: 1

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