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Preserve content with Get-AuthenticodeSignature#18774

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daxian-dbw merged 2 commits intoPowerShell:masterfrom
jborean93:authenticode-data
Apr 25, 2023
Merged

Preserve content with Get-AuthenticodeSignature#18774
daxian-dbw merged 2 commits intoPowerShell:masterfrom
jborean93:authenticode-data

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@jborean93 jborean93 commented Dec 13, 2022

PR Summary

Do not try and roundtrip the -Content bytes to a Unicode encoded string and then back to bytes. Instead just use the raw input bytes when validating the content signature.

PR Context

Fixes #18773

PR Checklist

Do not try and roundtrip the -Content bytes to a Unicode encoded string
and then back to bytes. Instead just use the raw input bytes when
validating the content signature.
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This PR has 135 quantified lines of changes. In general, a change size of upto 200 lines is ideal for the best PR experience!


Quantification details

Label      : Medium
Size       : +120 -15
Percentile : 47%

Total files changed: 4

Change summary by file extension:
.cs : +17 -15
.ps1 : +103 -0

Change counts above are quantified counts, based on the PullRequestQuantifier customizations.

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@iSazonov iSazonov requested a review from PaulHigin December 13, 2022 08:15
@iSazonov iSazonov added the CL-General Indicates that a PR should be marked as a general cmdlet change in the Change Log label Dec 13, 2022
@ghost ghost added the Review - Needed The PR is being reviewed label Dec 20, 2022
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ghost commented Dec 20, 2022

This pull request has been automatically marked as Review Needed because it has been there has not been any activity for 7 days.
Maintainer, please provide feedback and/or mark it as Waiting on Author

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Any updates on this one, have been a few months with CI being green.

@jborean93 jborean93 closed this Apr 19, 2023
@daxian-dbw daxian-dbw reopened this Apr 20, 2023
@ghost ghost removed the Review - Needed The PR is being reviewed label Apr 20, 2023
Comment on lines +537 to +538
string verificationContents = Encoding.Unicode.GetString(script.OriginalEncoding.GetPreamble()) + script.ScriptContents;
signature = SignatureHelper.GetSignature(path, verificationContents);
signature = SignatureHelper.GetSignature(path, Encoding.Unicode.GetBytes(verificationContents));
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The existing code seems wrong here -- the OriginalEncoding could be an encoding other than Unicode, and that means Encoding.Unicode.GetBytes(verificationContents) could be different byte sequences than the original bytes from the file.
I will make a change and see if all tests still pass.

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LGTM.
@SeeminglyScience I made a change on how we get the byte sequences for the content of a script file because the existing code seems incorrect to me. CIs still passed with my changes, but I'd like you to take a look just to make sure the changes make sense. Thanks!

private static byte[] GetContentBytesWithBom(Encoding encoding, string scriptContent)
{
ReadOnlySpan<byte> bomBytes = encoding.Preamble;
byte[] contentBytes = encoding.GetBytes(scriptContent);
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Unsure if this code path warrants it, but you could ArrayPool<byte>.Shared.Rent(encoding.GetMaxCharCount(scriptContent)) here to avoid some potentially LOH allocations here

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It's been using System.Text.Encoding.Unicode.GetBytes(fileContent); in GetWinTrustData method, so I guess the LOH allocation has not become a concern, but yes, it's a potential perf issue.

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LGTM. @SeeminglyScience I made a change on how we get the byte sequences for the content of a script file because the existing code seems incorrect to me. CIs still passed with my changes, but I'd like you to take a look just to make sure the changes make sense. Thanks!

Yeah I think your changes make sense. It may actually solve some finickyness with encoding requirements and signing that I vaguely remember hearing about. LGTM!

@daxian-dbw daxian-dbw merged commit 93e9c63 into PowerShell:master Apr 25, 2023
@jborean93 jborean93 deleted the authenticode-data branch April 25, 2023 19:35
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ghost commented Jun 29, 2023

🎉v7.4.0-preview.4 has been released which incorporates this pull request.:tada:

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Get-AuthenticodeSignature Displaying Inconsistent Behavior Between -FilePath and -Content

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