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filter Get-PEFeature {
<#
.SYNOPSIS
Retrieves key features from PE files that can be used to build detections.
.DESCRIPTION
Get-PEFeature extracts key features of PE files that are relevant to building detections.
Author: Matthew Graeber (@mattifestation)
License: BSD 3-Clause
.EXAMPLE
ls C:\Windows\System32\*.exe | Get-PEFeature
.EXAMPLE
ls C:\Windows\System32\*.exe | Get-PEFeature | ConvertTo-Json
#>
[CmdletBinding()]
param (
[Parameter(Position = 0, Mandatory = $True, ValueFromPipelineByPropertyName = $True)]
[String]
[Alias('FullName')]
$Path
)
$HeaderBytes = Get-Content -TotalCount 2 -Encoding Byte -Path $Path
if (($HeaderBytes.Count -ne 2) -or ([Text.Encoding]::ASCII.GetString($HeaderBytes) -ne 'MZ')) {
Write-Verbose "$Path is not a valid PE file."
} else {
$FileInfo = Get-Item -Path $Path
$FileVersionInfo = $FileInfo.VersionInfo
# If a path starts with %windir%, %ProgramFiles%, %ProgramFiles(x86)%, or %APPDATA%,
# replace it to account for alternate system drives
$ExpectedPath = $FileInfo.DirectoryName -replace "^$([Regex]::Escape($Env:windir))", '%windir%'
$ExpectedPath = $ExpectedPath -replace "^$([Regex]::Escape($Env:ProgramFiles))", '%ProgramFiles%'
$ExpectedPath = $ExpectedPath -replace "^$([Regex]::Escape(${Env:ProgramFiles(x86)}))", '%ProgramFiles(x86)%'
$ExpectedPath = $ExpectedPath -replace "^$([Regex]::Escape($Env:APPDATA))", '%APPDATA%'
$ExpectedPath = $ExpectedPath -replace "^$([Regex]::Escape($Env:LOCALAPPDATA))", '%LOCALAPPDATA%'
$OriginalFilename = $FileVersionInfo.OriginalFilename
$FileDescription = $FileVersionInfo.FileDescription
# Note that Get-AuthenticodeSignature will prefer catalog signatures over embedded Authenticode signatures.
$SignatureInfo = Get-AuthenticodeSignature $Path
$SigningStatus = $SignatureInfo.Status
$OSBinary = $SignatureInfo.IsOSBinary
$SignerThumbprint = $null
$SignerSubject = $null
$RootThumbprint = $null
$RootSubject = $null
if ($SignatureInfo.SignerCertificate) {
$SignerCertificate = $SignatureInfo.SignerCertificate
# These will be subject to change as the certificate approaches the end of its validity period
$SignerThumbprint = $SignerCertificate.Thumbprint
$SignerSubject = $SignerCertificate.Subject
# Build a signer chain so the root certificate info can be extracted.
$SignerChain = New-Object -TypeName Security.Cryptography.X509Certificates.X509Chain
$null = $SignerChain.Build($SignerCertificate)
$RootCertificate = $SignerChain.ChainElements[$SignerChain.ChainElements.Count - 1].Certificate
$RootThumbprint = $RootCertificate.Thumbprint
$RootSubject = $RootCertificate.Subject
}
[PSCustomObject] @{
ExpectedPath = $ExpectedPath
ExpectedFileName = $FileInfo.Name
OriginalFileName = $OriginalFilename
FileDescription = $FileDescription
SigningStatus = $SigningStatus
IsOSBinary = $OSBinary
SignerSubject = $SignerSubject
SignerThumbprint = $SignerThumbprint
RootSubject = $RootSubject
RootThumbprint = $RootThumbprint
}
}
}
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