dsccommunity / dsccommunity/SChannelDsc

CipherSuites: Using 'Absent' for named CipherSuites on default installations does not work.

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bug good first issue help wanted
Dominant language
PowerShell
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Description

We were considering to use the 'CipherSuites' resource to remove unwanted ciphersuites due to regulatory requirements.
Unfortunately, we ran into some issues.

Using 'Absent' for named CipherSuites on a default Windows installation does not work for Windows installations where CipherSuites have not been previously configured.
I believe it is caused by the registry key HKLM\SOFTWARE\Policies\Microsoft\Cryptography\Configuration\SSL\00010002:Functions is non-existent when the OS is in default configuration.

Registry:
registry
DSC verbose output:
ciphersuites

Since the registry property does not exist the TestScript will not return $False, as the unwanted cipersuites are not present.

I was thinking the Get-TlsCipherSuite, Disable-TlsCipherSuite, and Enable-TlsCipherSuite commands should work better than editing the registry.
But these commandlets are not compatible with Windows Server 2012 R2 and older, albeit that should not be the worst issue after October 10th.

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reproducing the CipherSuites resource behavior with Absent on a default Windows installation, focusing on the TestScript and the missing HKLM\SOFTWARE\Policies\Microsoft\Cryptography\Configuration\SSL\00010002:Functions value. Compare the result with Get-TlsCipherSuite, Disable-TlsCipherSuite, and Enable-TlsCipherSuite, including compatibility with Windows Server 2012 R2 and older; done means unwanted named cipher suites are handled correctly from the default state.

Written by the indexing model from the issue text.

Assessment

Tech stack
powershell
Domain
operating-systems, security
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
35/100

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