Powershell signing, makecert.exe and group policy – Part 1

We don’t have a pki infrastructure at my current job, and I like to keep my powershell scripts on my network drive. So I needed a way to run my .ps1 files off a network drive. Setting Set-ExecutionPolciy to Unrestricted seemed like a bad idea. So I looked into using a signed script and setting Set-ExecutionPolicy to RemoteSigned. I could not justify $300 to buy a trused third party cert, so I looked at makecert.exe from the Windows SDK.

First step make the Root CA cert, private key, and pxf.

  1. makecert -n “CN=RootName” -a sha1 -eku -r -sv Root.pvk Root.cer
  2. pvk2pfx.exe -pvk Root.pvk -spc Root.cer -pfx Root.pfx -pi password

makecert and pvk2pfx can be found in the Windows SDK or in the Visual Studio bin directory. First command results in a private key (.pvk) and a certificate (.cer). Second command makes a pfx out of the first 2.

Second step is to create a certificate from the root cert above.

  1. makecert -pe -n “CN=Certificate” -a sha1 -eku -ic Root.cer -iv Root.pvk -sv Certificate.pvk Certificate.cer
  2. pvk2pfx.exe -pvk Certificate.pvk -spc Certificate.cer -pfx Certificate.pfx -pi password

Now we are ready to sign our powershell script.

  1. $cert = Get-PfxCertificate Certificate.pfx
  2. Set-AuthenticodeSignature -Filepath script.ps1 -Cert $cert

Probably can be combined into one line, but I am not a guru yet.

Next post will talk about how I added this certs above to all the servers.

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