Another method to gain administrative privileges without being an administrator is changing some registry values to make the operating system think you are the Administrator.

When a user is created, an identifier called Relative ID (RID) is assigned to them. The RID is simply a numeric identifier representing the user across the system. When a user logs on, the LSASS process gets its RID from the SAM registry hive and creates an access token associated with that RID. If we can tamper with the registry value, we can make windows assign an Administrator access token to an unprivileged user by associating the same RID to both accounts.

In any Windows system, the default Administrator account is assigned the RID = 500, and regular users usually have RID >= 1000.

To find the assigned RIDs for any user, you can use the following command:

wmic useraccount get name,sid

The RID is the last bit of the SID (1010 for thmuser3 and 500 for Administrator). The SID is an identifier that allows the operating system to identify a user across a domain, but we won't mind too much about the rest of it for this task.

Now we only have to assign the RID=500 to thmuser3. To do so, we need to access the SAM using Regedit. The SAM is restricted to the SYSTEM account only, so even the Administrator won't be able to edit it. To run Regedit as SYSTEM, we will use psexec,

PsExec64.exe -i -s regedit

From Regedit, we will go to HKLM\SAM\SAM\Domains\Account\Users\  where there will be a key for each user in the machine. Since we want to modify thmuser3, we need to search for a key with its RID in hex (1010 = 0x3F2). Under the corresponding key, there will be a value called F , which holds the user's effective RID at position 0x30:

Notice the RID is stored using little-endian notation, so its bytes appear reversed.

We will now replace those two bytes with the RID of Administrator in hex (500 = 0x01F4), switching around the bytes (F401):

The next time thmuser3 logs in, LSASS will associate it with the same RID as Administrator and grant them the same privileges.

If you did everything correctly, you should be logged in to the Administrator's desktop.