delete some sequence of bytes in Powershell [duplicate] - powershell

Question

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Methods to hex edit binary files via Powershell
(4 answers)
Closed 3 years ago.
I have a *.bin file. How can I delete with poweshell some part of bytes (29 bytes, marked yellow) with repeatig sequence of bytes (12 bytes, marked red pen)? Thanks a lot!!

Answer 1

Using a very helpful article and ditto function I found here, it seems it is posible to read a binary file and convert it to a string while not altering any of the bytes by using Codepage 28591.
With that (I slightly changed the function), you can do this to delete the bytes in your *.bin file:
function ConvertTo-BinaryString {
# converts the bytes of a file to a string that has a
# 1-to-1 mapping back to the file's original bytes.
# Useful for performing binary regular expressions.
[OutputType([String])]
Param (
[Parameter(Mandatory = $True, ValueFromPipeline = $True, Position = 0)]
[ValidateScript( { Test-Path $_ -PathType Leaf } )]
[String]$Path
)
$Stream = New-Object System.IO.FileStream -ArgumentList $Path, 'Open', 'Read'
# Note: Codepage 28591 returns a 1-to-1 char to byte mapping
$Encoding = [Text.Encoding]::GetEncoding(28591)
$StreamReader = New-Object System.IO.StreamReader -ArgumentList $Stream, $Encoding
$BinaryText = $StreamReader.ReadToEnd()
$StreamReader.Close()
$Stream.Close()
return $BinaryText
}
$inputFile = 'D:\test.bin'
$outputFile = 'D:\test2.bin'
$fileBytes = [System.IO.File]::ReadAllBytes($inputFile)
$binString = ConvertTo-BinaryString -Path $inputFile
# create your regex: 17 bytes in range of \x00 to \xFF followed by 12 bytes specific range
$re = [Regex]'[\x00-\xFF]{17}\xEB\x6F\xD3\x01\x18\x00{3}\xFF{3}\xFE'
# use a MemoryStream object to store the result
$ms = New-Object System.IO.MemoryStream
$pos = $replacements = 0
$re.Matches($binString) | ForEach-Object {
# write the part of the byte array before the match to the MemoryStream
$ms.Write($fileBytes, $pos, $_.Index)
# update the 'cursor' position for the next match
$pos += ($_.Index + $_.Length)
# and count the number of replacements done
$replacements++
}
# write the remainder of the bytes to the stream
$ms.Write($fileBytes, $pos, $fileBytes.Count - $pos)
# save the updated bytes to a new file (will overwrite existing file)
[System.IO.File]::WriteAllBytes($outputFile, $ms.ToArray())
$ms.Dispose()
if ($replacements) {
Write-Host "$replacements replacement(s) made."
}
else {
Write-Host "Byte sequence not found. No replacements made."
}