CODEWITHSUNDEEP
arrayspowershellreflection.net-assembly
youssef jabrane
youssef jabrane

Reputation: 39

Loading a .NET assembly from a byte array

I'm getting this error when I try to load a program in memory

error:

GAC    Version        Location
---    -------        --------
False  v2.0.50727

here my code:

$Path = "D:\calc.exe"
$bytes = [System.IO.File]::ReadAllBytes($Path)

$string = [System.Convert]::ToBase64String($bytes)

$bytees = [System.Convert]::FromBase64String($string)
[System.Reflection.Assembly]::Load($bytees)

Upvotes: 1

Views: 7105

Answers (1)

mklement0
mklement0

Reputation: 437783

As Maximilian Burszley points out, what you're seeing is not an error.

In fact, it indicates that your assembly was successfully loaded from your byte array:

The System.Reflection.Assembly.Load method returns a System.Reflection.Assembly instance representing the loaded assembly, and since you're not assigning that return value to a variable, PowerShell implicitly prints a friendly representation of the object to the console, and this is what you're seeing; if you append | Format-List to your [System.Reflection.Assembly]::Load($bytees) call, you'll see more detailed information about the newly loaded assembly.

Any public types defined in the assembly should now be available in your PowerShell session; however, given that you're indicating an *.exe files as the source, perhaps you want to execute the assembly as you would the original executable, possibly with command-line arguments.

To provide a full example:

# Note: This must be an executable or DLL compiled for .NET
$Path = "D:\calc.exe"

# Get Base64-encoded representation of the bytes that make up the assembly.
$bytes = [System.IO.File]::ReadAllBytes($Path)
$string = [System.Convert]::ToBase64String($bytes)

# ...

# Convert the Base64-encoded string back to a byte array, load
# the byte array as an assembly, and save the object representing the
# loaded assembly for later use.
$bytes = [System.Convert]::FromBase64String($string)
$assembly = [System.Reflection.Assembly]::Load($bytes)


# Get the static method that is the executable's entry point.
# Note: 
#   * Assumes 'Program' as the class name, 
#     and a static method named 'Main' as the entry point.
#   * Should there be several classes by that name, the *first* 
#     - public or non-public - type returned is used.
#     If you know the desired type's namespace, use, e.g.
#     $assembly.GetType('MyNameSpace.Program').GetMethod(...)
$entryPointMethod = 
 $assembly.GetTypes().Where({ $_.Name -eq 'Program' }, 'First').
   GetMethod('Main', [Reflection.BindingFlags] 'Static, Public, NonPublic')

# Now you can call the entry point.
# This example passes two arguments, 'foo' and 'bar'
$entryPointMethod.Invoke($null, (, [string[]] ('foo', 'bar')))

Note: A generalization of the above - which doesn't require you to know the class name and invokes the CLI entry point without arguments - can be found in this answer.

Upvotes: 3

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