Controlling PowerShell Function (Re)Definition

re: Controlling PowerShell Function (Re)Definition

Keith Hill — Sat, 31 Mar 2007 11:06:41 GMT

Speaking of the variable provider it sure would be nice if the function provider borrowed the "Description" property that can be associated with variables. Then a package could identify the functions that it defines by setting the function Description to a particular value.

re: Controlling PowerShell Function (Re)Definition

PowerShell Team — Wed, 31 Jan 2007 02:42:55 GMT

Once an attacker has code running on a victim's computer, they can do anything they wish. Why play around with their profile, when you can just do the Remove-Item damage right away?

The important thing to remember is that code running on the computer can do anything that the user can.

re: Controlling PowerShell Function (Re)Definition

Rob Kenny — Sat, 27 Jan 2007 20:34:16 GMT

At the moment it is possible to do the following:

set-item function:Get-ChildItem {"Bar"}

> Get-ChildItem

> Bar

If a users execution policy allows it (e.g. RemoteSigned or weaker) malicious code could be added to the My Documents\WindowsPowerShell\Microsoft.PowerShell_profile.ps1 profile re-writing common functions e.g

Set-Item function:Get-ChildItem {remove-item C:\*.* -recurse -force}

I am missing something in my understanding?

re: Controlling PowerShell Function (Re)Definition

Adrian Milliner — Fri, 26 Jan 2007 20:27:09 GMT

That's pretty much what I said in my post... unfortunately, the trackback comment here didn't make it obvious that there was more at http://ps1.soapyfrog.com/2007/01/26/making-functions-really-read-only/ :(

re: Controlling PowerShell Function (Re)Definition

PowerShell Team — Fri, 26 Jan 2007 16:22:30 GMT

> However, making a function constant does not prevent it from being shadowed in child scopes. Given that a child scope is created in an..

Correct. That is what -OPTION ALLSCOPE is for. This defines the element for all scopes. Here is an example:

PS> set-item function:bar {"Constant"} -option constant,allscope

Jeffrey Snover [MSFT]

Windows PowerShell/MMC Architect

Visit the Windows PowerShell Team blog at: http://blogs.msdn.com/PowerShell

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Making functions really read-only

ps1.soapyfrog.com — Fri, 26 Jan 2007 13:24:48 GMT

Over at the excellent PowerShell Team Blog, Bruce Payette wrote about Controlling PowerShell Function (Re)Definition.

However, making a function constant does not prevent it from being shadowed in child scopes. Given that a child scope is created in an..

Adventures in SPWonderland - Powershell User Group Meeting

Adventures in SPWonderland - Powershell User Group Meeting — Fri, 26 Jan 2007 00:36:50 GMT

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Powershell User Group Meeting

Adventures in SPWonderland — Fri, 26 Jan 2007 00:36:47 GMT

Controlling PowerShell Function (Re)Definition

re: Controlling PowerShell Function (Re)Definition

re: Controlling PowerShell Function (Re)Definition

re: Controlling PowerShell Function (Re)Definition

re: Controlling PowerShell Function (Re)Definition

re: Controlling PowerShell Function (Re)Definition

Making functions *really* read-only

Adventures in SPWonderland - Powershell User Group Meeting

Powershell User Group Meeting

Making functions really read-only