I want to load my kernel-mode driver on Windows 11 without test signing mode
What kind of a code signing certificate do I need to buy and sign my driver with? EV? OV?
I am trying to get our libusb-win32 driver to work with different Windows OS. I already successfully installed it on 7, 8 and 10 with a selfsigned certificate that I imported into the root and trustedpublisher.
What remains is to buy an official certificate and distribute it. Since Windows 10 there is the need to use EV for kernel mode drivers but libusb already ships the .sys and .dll with valid signature.
Since theres quite a difference in pricing the question is: Do I need an EV certificate to sign the .cat or can Windows differentiate between installing with standard certificate signature in the .cat and loading the kernel module with the embedded kernel module signature?
I need some clarification about driver signing in Windows 10.
We have working driver package that uses Winusb.sys driver that is signed from the start by Microsoft. But to install this driver to customer machine we have our own *.inf and 2 generated *.cat files for each supported platforms. Currently we have no issues using this driver in Windows 10 since modifications for Windows 8 support, but we want to add some additional hardware devices support in near future to driver, so it will be modified and need to be resigned.
The question is what certificate (Extended Validation (“EV”) Code Signing Certificate or just Standard Certificate) do we need to sign these *.cat files, so our driver can be installed correctly at Windows 10. Also is it necessary to submit out driver to Windows Hardware Developer Center Dashboard portal?
I saw this and some other articles that states, EV certificate signing is needed only by kernel-mode drivers (it seems after 90 days of Win10 release also user-mode drivers), but WinUSB driver is kernel-mode and fully supported and initially signed by Microsoft. So again what kind of certificate do we need to sign *.cat files and do we need to submit them to Microsoft portal?
The files structure before signing looks like
driver
|--*.inf
|--*amd64.cat
|--*x86.cat
|--amd64
|--WdfCoInstaller01009.dll
|--winusbcoinstaller2.dll
|--i386
|--WdfCoInstaller01009.dll
|--winusbcoinstaller2.dll
|--ia64
|--WdfCoInstaller01009.dll
|--winusbcoinstaller2.dll
My company also uses WinUSB for one of our devices. We currently use a "driver signing" certificate from Godaddy. Once the certificate is installed on your machine (they have step-by-step instructions for how to do this), you need to generate a pfx file and then you can use the signtool utility to sign the security catalog.
This link was a great resource for me: http://www.davidegrayson.com/signing/
Here is a great SO answer which covers the creation of self-signed CA and then signing executables with the obtained certificates: How do I create a self-signed certificate for code signing on Windows?.
I have read a lot of discussions online on how the driver signing works and the answer seems to be almost unequivocally that you can't load unsigned or self-signed drivers without having the test mode enabled. However, the answer I linked to and especially one comment by Roger Lipscombe seems to provide a contradicting view:
If you want to use this for signing drivers, you need to import the CA
certificate into the machine store. My example imports it into the
user store, which is fine for most software, for test/internal
purposes.
To me, it looks like I would be able to install drivers with self-signed certificates (issued by a self-signed CA) as long as the CA cert was imported to the machine store. I won't have to make any other changes to the system (disabling test mode by pressing F8 on boot menu, messing with boot configuration flags such as TESTSIGNING or NOINTEGRITYCHECKS).
Am I correct? What are the obstacles, if any, that this method is not used more widely when people need to load drivers that have no proper digital signatures provided (such as old printer drivers etc.). Instead, people rely on booting to test mode or a third-party software (DSEO) which tampers with your system files to run such drivers.
What are the drawbacks of this method? The process described in the above SO question needs admin privileges but installing drivers should need them anyway. Trusting a self-signed CA might be a security risk - but won't disabling all signature checks be even bigger security risk?
No, this is unfortunately not possible, starting from Windows Vista and Windows Server 2008.
The driver has to be cross-signed. Creating your own CA and adding it to the machine store won't be enough because the newly created CA won't be trusted by the Windows chain of trust.
Driver Signing Requirements for Windows
In Windows Vista and Windows Server 2008, new features take advantage of code-signing technologies, and new requirements for security in the operating system enforce the use of digital signatures for some kinds of code.
Components must be signed by a certificate that Windows "trusts" as described in the white papers on this site.
One of the white papers referred is Digital Signatures for Kernel Modules on Windows
which describes the load process and explains why self-signing won't be sufficient:
When a driver is loaded into kernel memory, Windows Vista verifies the digital signature of the driver image file. Depending on the type of driver, this can be either the signed hash value in the catalog file or an embedded signature in the image file itself. The cross-certificates that are used when signing the kernel driver package are used for the load-time signature verification; each certificate in the path is checked up to a trusted root in the kernel. The load-time signature check does not have access to the Trusted Root Certificate Authorities certificate store. Instead, it must depend on the root authorities that are built into the Windows Vista kernel.
As mentioned earlier, this is also outlined on the Requirements for Device Driver Signing and Staging page:
The 64-bit versions of Windows 7 and Windows Server 2008 R2 have special signature requirements for kernel mode device drivers. If you use a 64-bit version of Windows, then you cannot create your own certificate for signing. Instead, you must use a Software Publishing Certificate that chains to an approved certification authority (CA).
The valid CAs for signing kernel mode drivers can be found on the following page:
Cross-Certificates for Kernel Mode Code Signing
User mode drivers will work on Windows 10 X64 with secure boot and everything with self signed certs as long as you add the cert to the Trusted Root CAs. Kerner mode drivers only work with paid MS trusted root CAs.
you are correct, if you create a self signed certificate and save it in user store (or machien store) as a Trusted CA, it will work for you... but keep in mind that:
Secure boot will not work for you.
This is a security breach, if someone get a hold of the certificate, they will have to run kernel mode code on your system.
Other option, is to buy Trusted Code Signing Certificate from GoDaddy :)
I have a kmfd driver and i am buying a certificate from http://www.digicert.com/code-signing/ , will this certificate work on windows 7 ? or do i need to buy it from verisign only , they charge a whopping 400$/yr whereas this is 178$/year .