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AzurePublicIPAddresses Version 0.7 released

I have just released a new version of my AzurePublicIPAddresses PowerShell module. With this release (version 0.7), support for the UK data centers has been introduced.

You can learn more about using the module from my blog post, Working with Azure’s public IP addresses. James Bannan has put together a post, Update User Defined Routes for Azure Datacenters with Azure Automation, where he talks about updating user defined routes using the information from my module.

The module can be obtained via the PowerShell Gallery or from GitHub.

Kieran Jacobsen

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Microsoft Releases PowerShell to Linux and OS X!

The Announcement

On Friday I woke to the remarkable news that PowerShell has been open sourced, and made available on Linux and Mac. You should read the PowerShell Team’s Announcement, and Jeffrey Snover’s announcement. There is an excellent video on Channel 9, PowerShell on Linux and Open Source.


I want to first start by congratulating everyone over at Microsoft, in particular the PowerShell Team and Jeffrey Snover.  I have been an avid user of PowerShell since the codename Monad days and it has been one of the few technology constants in my 10 years in the industry (the other being Active Directory).

It has been a long road since the original Monad Manifesto to reach this milestone, and it could not have been accomplished without Jeffrey’s amazing efforts. Don Jones posted up an excellent article on just why this is such an important accomplishment, you should also read the PowerShell Team's post: Windows PowerShell is now “PowerShell”: An Open Source Project with Linux support – How did we do it?.

This wasn’t an unexpected announcement, in fact, it was quite expected. I never doubted that this accouncement would never occur, to me it wasn't a matter of IF PowerShell would become open source, but WHEN.

Like almost everyone I was in the dark that this was happening, but I had a gut feeling things were close. There were plenty of clues and signs that this was about to happen: .Net Core, Nano Server, Bash on Windows and even the inclusion of Pester in Windows 10. Still, I wasn’t quite expecting to wake up on Friday to the news.

What Was Announced

Microsoft announced that from PowerShell would be run as an open source project, and that an intial alpha release would be made available. This release is version 6.0 and is currently available PowerShell Core, for Windows, Ubuntu, Centos and Mac OS X, with more platforms expected in the future.

So what is PowerShell Core? Core is a cut down version of PowerShell, designed to run on top of the .Net Framework Core edition. We have already seen PowerShell Core in releases of Windows Nano Server. Core edition does not support all of the functionality that the Desktop version will contain.

It is worth noting that this is an alpha release, and as such, you should treat it, and have suitable expectations. This isn’t a production ready release, and likely isn’t going to be for a while yet.

Changes to Remoting

One of the big items in the announcement is the changes to the PowerShell Remoting Protocol (MS-PSRP). Currently the MS-PSRP only supports WinRM, however with PowerShell 6.0, support for SSH will be introduced.

This isn't executing commands over SSH, what is actually occuring is that the objects forming our request are serialized into XML, transmitted over SSH, and then de-serialized. SSH is used as a transport layer for the remoting protocol, mush like WinRM is currently used. SSH is not replacing WinRM, just providing another option for administrators to use.

What this does mean is that you will start to be able to manage your Windows servers from your Macbook, and your Linux servers from your Windows 10 machine. 

I had a significant number of issues with WinRM. From its poor performance to its insecure defaults, and I am hoping that the inclusion of SSH support should start to make a difference. If nothing else, it provides a number of new and interesting ways to design and manage our environments.

What’s Missing?

This is a PowerShell Core release, it is based upon the .Net Core, and as such, some things are just simply not going to be there. It should also be obvious that things like WIM and CIM are not supported and will not be available. Get-EventLog isn't there either, as it doesn't fit with the Linux log file model.

Security Impacts!

Security teams should begin to familiarise themselves with not only PowerShell 6.0 and its remoting changes now, but also with Nano Server prior to their release. With a cross pollination of administration teams, that is, Windows and Linux administrators managing each other's eco systems, we are going to see changes in our network architecture and security requirements. SSH connections from a Windows system will begin to move from the abnormal to the normal.

PowerShell is already a highly desirable target for attackers, with more instances of attacks using PowerShell on a daily basis. With the move to include PowerShell on Linux systems, especially servers, the attraction of PowerShell to attacks is likely to increase. The ability to move from a Windows client to that lovely Red Hat farm makes PowerShell an awesome attacker and Red Team tool. Some in the security industry are already calling PowerShell the next Flash or Java for cross platform hacking.

I guess the other thing we need to consider is that a significant number of people are probably pouring over the PowerShell source code with the intention of finding vulnerabilities. Whilst the chances are probably small that someone might find a significant issue, there is still the possibility.

Other Investments to Watch

Looking through the known issues document, and also the PowerShell Teams announcement, two items stood out to me:

  • The ability to write CMDLets in Python and other languages
  • Unix-style wildcard expansion

Getting Started

The best place to start is the PowerShell Home Page, after that, the PowerShell GitHub repository is your next stop.

Windows

It is worth noting that installing PowerShell 6.0 will not replace your existing PowerShell version, it is installed side-by-side. It is also worth noting that this installs Core edition and not Desktop edition.

Simply grab the right MSI, and run the installer! 

Linux

There are official guides for Centos 7, Ubuntu 14.04 and Ubuntu 16.04. The Centos guide should also work for Red Hat.

There are also two great guides:

Mac OS X

You can find Microsoft's instructions for installing here, for more detail check out The IT Hollow's guide, Install PowerShell on Mac.

Other Install Options

There are a bunch of other ways you can get started with PowerShell 6.0:

Once you have PowerShell installed, take a look at some of the demos available.

If you are new to PowerShell and are coming from a Linux or Unix background, check out: A Unix Persons Guide to PowerShell.

Contributing

The great part of any open source project is that we can all play our own part and contribute. You don’t need to be a developer to contribute either, I often contribute to projects by helping out with documentation, or cleaning up simple default configuration files and example usage.

If you feel like contributing, start by reading the contribution guidelines. I also recommend you take a look at the governance process. The Governance process includes how to raise issues, make contributions, and participate in the design process via RFCs. The documents also provide information on the roles and responsibilities of everyone involved in the project.

I recently spent some time working on some issues with the documentation of the PSScriptAnalyzer. The contribution process is similar to that of PowerShell, and it was super simple and easy to create a pull request and work with the PowerShell Team. I would like to point out that if your pull request is large, you may need to sign the Contribution License Agreement, don’t worry, it isn’t difficult and only takes a few seconds to complete. The agreement just covers that the work you are completing is yours and not of anyone else.

Tool Updates

Update your development tools! Virtual Studio Code (and the PowerShell extension), PSScriptAnalyzer and the ISE Steroids have all been updated to include support for PowerShell 6.0.

More Information

With all of this you should be well on your way to working with PowerShell on Linux and Mac OS X! Good luck and don't forget to share your experiences!

Kieran Jacobsen

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PowerShell 5, DSC, SABnzbd and Sonarr (Part 1)

I have been trying to do a lot more with PowerShell DSC of late, including writing my own DSC resources.

Last week, I decided to write some resources for SABnzbd and Sonarr. Why? Well firstly for practice, but also because no one else has looked at building up packages for these apps (there wasn’t even Chocolatey packages).

I am not going to go into detail on implementing classes in PowerShell, instead checkout:

SABnzbd

The module cSABnzbd contains a single resource: cSABnzbdInstall. This resource specifying:

  • Ensure: <String> { Ensure | Absent }
  • ServiceCredential: <PSCredential>

If you opt for Ensure to be “Present”, then the resource will install and update SABnzbd. That is right, as new versions are released, it will be automatically updated.

The ServiceCredential allows for us to control what account the SABnzbd services run as. If not specified, LocalHost will be used.

GetLatestVersion()

SABnzbd hosts both its source code and its binary releases in GitHub. This is great! GitHub provides a simple REST API that allows us to very easily and dynamically get the latest release for a project.

If we want to get information on the latest release for a particular repository, we simply perform a get request on https://api.github.com/repos/{owner}/{repo}/releases/latest. The response will contain things like the version name, the release date and the assets in the release. The GitHub API doesn’t need any authentication credentials or tokens; these requests can be performed anonymously.

Performing the API request for sabnzbd the URL for us would be https://api.github.com/repos/sabnzbd/sabnzbd/releases/latest, and the returned information looks like:

The function is pretty simple:

Get()

The Get() function is quite easy to implement. We simply need to call Get-Package, and sets the result against the ensure parameter. We then return the object as required. The result is:

Test()

The Test() is also pretty simple. We use Get-Package again to see if the package is installed or not.

If Ensure = ‘Present’, then we need to check:

  1. If no package was returned, then return false
  2. If it is installed, compare the installed version to the version number returned using GetLatestVersion()

If Ensure = ‘Absent’, then we simply compare $Package to $null.

Set()

Now the Set() function is more complex.

If Ensure = ‘Present’, then we need to:

  1. Find the latest .exe in the release information using GetLatestVersion()
  2. Download the file, this is listed under the assets (look for a .exe).
  3. Silently run setup using the /S switch
  4. Install and start the services (optionally running under the user account specified with ServiceCredential).

If we don’t want SABnzbd installed, then we simply call the uninstall.exe.

Using and Configuring SABnzbd

You should be able to access SABnzbd via http://localhost:8080. When you connect the first time, you will be stepped through the initial setup wizard. I haven’t included any resources for specifying any settings like servers, scheduling or custom folders, you can do this as you would normally do. For more help, try the User Manual.

Getting the module

The module can be found on:

You will need PowerShell 5 or greater installed due to the use of Classes. 

If you encounter any issues, please raise an issue on the GitHub page.

In the next post we will take a look at Sonarr.

Kieran Jacobsen

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Working with Azure’s public IP addresses

If you have spent much time working with Microsoft Azure, Amazon AWS or any public cloud provider, you have probably started to wonder about how many public IPv4 addresses they have. Whilst we know there is a limit to the number of addresses, and that we have reached these limits, it still seems like there are quite a few to go around.

I recently had the need to get a listing of all the Azure subnets, and whilst I did this, I thought it would be good to make a reusable PowerShell module to assist.

Microsoft makes this process pretty easy, providing an XML file under the Microsoft Download Center title: Microsoft Azure Datacenter IP Ranges. There are a few things to note about this file:

  • It contains all compute (including SQL),
  • It is updated on Wednesday (Pacific Time), but changes are effective from the following Monday (Pacific Time), and,
  • The file will contain only production Azure DCs, for instance, at the time of writing the German and Canadian DCs are not contained in the file.

I have developed a PowerShell module that simplifies working with this file by developing CMDLets that:

  1. Allowing for automated downloads of the file, and,
  2. Allow for specific DCs to be extracted

Get-MicrosoftAzureDatacenterIPRangeFile provides us with a method to simply and easily access the XML document. If called without parameters, we will get the XML document returned, however we can opt to save the file to disk for future processing.

Then we have Get-MicrosoftAzureDatacenterIPRange. With this CMDLet, we can get a list of objects containing the subnets (in CIDR format) for a specific DC or for all of the DCs. You can specify the path to a previously downloaded file, or it can download the file for us (and keep it in memory).

The module can be found on:

I have tested this module against PowerShell 5, however there should be no issue with earlier versions (I recommend PowerShell 3 or higher). If you encounter any issues, please raise an issue on the GitHub page.

Just in case you were wondering, Azure has approximately 1700 subnets, or around 5.8 million IPv4 addresses!

Kieran Jacobsen

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PushOver and PowerShell

Pushover is an exceptional method for integrating notifications into our PowerShell scripts and workflows. Pushover gives us a simple method to send notifications to devices. I discovered Pushover in 2012, and have been maintaining a PowerShell module ever since.

The purpose of my PowerShell module is to allow you to:

  • Send Pushover notifications,
  • Test API, user, group and device tokens; and,
  • Retrieve the details of a notification receipts.

I have kept the module and the CMDLets as simple as possible. Sending a notification is a simple as specifying an API token, a user token, and a message. Pushover supports a whole lot of other functionality, and the Send-Pushover CMDLet supports:

  • Users and Group tokens,
  • Device names,
  • Priority levels (including lowest, low, normal, high and emergency),
  • Message titles,
  • A URL,
  • Custom date and time stamps; and,
  • Custom sounds.

When submitting a notification, we get the following back:

  • A response code,
  • A request identifier; and,
  • A Boolean request response code. I recommend in your scripts validating against this success property.

Most of the time, Pushover notifications are pretty straight forward. It is important to note that emergency messages, are different. Pushover will continue to notify a user until they acknowledge it. If you are sending something that is this important, you want to know if someone actually cares about it.

When a user accepts the notification, Pushover records the who, when and where. We can make use of this information either through a callback URL in a request, or through the receipt ID returned.

Now we have a variety of tokens, API, user groups and devices. How do we know if they are all valid? You can verify these are all valid using the Test-Pushover CMDLet.

Right now I haven’t included any support for Pushover’s subscription, group or licensing features. This isn’t due to any difficulties, but more that I haven’t needed these. Of course, I am always happy to have a pull request submitted for this!

You can get module from GitHub or via the PowerShell Gallery.

Kieran Jacobsen

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Presentation: Azure Automation invades your data centre

I recently had the pleasure to present on Azure Automation and hybrid workers to the Melbourne Azure Group. I really want to thank all of those who attended, Chris Padgett for inviting me to present and Microsoft for the use of their facilities.

My presentation, Azure Automation invades your data centre, covered off the ins and outs of Azure Automation and extending its reach to your own data centre with hybrid workers. I also spoke about using web hooks and the Azure Automation Authoring Toolkit.

If you haven’t looked at Azure Automation or hybrid workers, I thoroughly recommend that go and take a look. There are a number of excellent resources out there for you to make a start, including:

You can find the runbooks I used in my presentation up on GitHub, https://github.com/poshsecurity/PoshSecurityAzureAutomation and you can download the slides or view them with SlideShare here.

Kieran Jacobsen

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Presentation: Exploiting MS15-034 In PowerShell

Last night I had the opportunity to present at the first Melbourne PowerShell Meetup. I want to thank those who attended and in particular, thank David O’Brien for his work in organising such a great event, thanks also go to Versent and Level 3 for providing the food and the event space.

My presentation, Exploiting MS15-034 and working with TCP connections in PowerShell was first up for the night and extremely well received.

As promised, you can find the PowerPoint slides here, or up on SlideShare. You can find the code from the demonstrations up here on GitHub.

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SYSLOG, PowerShell, Pester and the PowerShell Gallery

Out of all of the content on this site, my posts about integrating SYSLOG and PowerShell are by far the most popular. Whilst this might seem peculiar to some, I can definitely see the value that this would bring to an enterprise environment.

I first wrote about my initial integration attempts back in 2014. In fact that post, Sending SYSLOG messages from PowerShell, had been the reigning champ as most popular until very recently, losing its title to my work on MS15-034 and my comments on Skype for Business.

In early 2015, a number of bugs were found in the formatting of the UDP messages it sent. I invested time and energy into resolving these issues, resulting in RFC 3164 and RFC 5424 compliant messages being sent. I discussed the process of resolving them in the post, Revisting SYSLOG in PowerShell.

Well, a few weeks ago, it came to my attention that I hadn’t quite ironed out all of the bugs. I spent some time, worked through some possible fixes and implemented them. The issue turned out that when selecting the hostname to send, there was a chance it would send either the wrong IP address, not a blank hostname. It didn’t take long to come up with some new logic (which I still believe could be better), but I wanted to shake the code and determine if there were any others hiding out.

Pester

The best way to repeatedly test PowerShell functions, CMDLets, modules and scripts is through the use of Pester. I will admit, that I hadn’t, until this point, taken a look at Pester and this seemed like a great opportunity.

I started with the low hanging fruit. How about we check the input validation is correct? This shook out some validation bugs, and whilst there I realized I could implement parameter sets to improve things.

Now came the hard part. How do I validate the format of the messages that I am sending?

Well, firstly we need to mock some of the CMDLets that are used, to ensure our output is predictable. Things like Get-Date need to be mocked so we can control the messages being sent. I would also modify some of the environment variables for that execution to ensure things like hostnames were predictable.

But the messages are still sent over UDP, how do we look inside them?

The easiest method I found, well it was a bit of a pain, but it produces repeatable and testable outcomes. I would start by setting up a job using New-Job that had a basic UDP listener. The code simply waits for a UDP packet to come in, and returns as output the contents of that packet. Once I have something listening, all I need to do is run my command, and then get the output (of the now completed job) which will contain the SYSLOG message sent.

It is messy, but it allowed me to shake out another logic issue, which has to be a good thing.

A New Name and a New Home

With all of this work, one last thing has always bugged me about the module, the Name! Whilst PowerShellSyslog is simple and descriptive, it has always felt a little bit crude. Now I suck at coming up with names, so I stuck with what seems to be a habit now and stuck Posh- in front of what it actually does. The module and the GitHub repository have now been renamed to Posh-SYSLOG.

I have been attempting, where possible to move my major GitHub repositories to the PoshSecurity banner. As such, I have moved the Posh-SYSLOG to here: https://github.com/poshsecurity/Posh-SYSLOG

GitHub creates redirects when you move or rename a repository, so all of your current links and working copies should continue to work.

It’s worth noting that if you are manually importing the module via “import-module PowerShellSyslog”, you will need to update this to reflect the new module name.

Easier Installation via the PowerShell Gallery

PowerShell 5 brings a bunch of improvements and new features. One feature that I am so excited about is the Package Management functionality, as it provides new deployment options for not only conventional installed applications but also for PowerShell modules and scripts. The PowerShell Gallery allows administrators and developers to download, install and share modules and scripts.

I have made Posh-SYSLOG available via the gallery here. I will be working to ensure that the gallery is kept up-to-date with the GitHub repo. If you want to install via the gallery, simply type “install-module –name Posh-SYSLOG”.

Future and Thanks

If you are using the module, and find an issue, please feel free to raise an issue on GitHub, I will respond as quickly as possible. I want to ensure this module is the community’s preferred module for connecting to SYSLOG and are happy for any questions, comments or feedback.

I want to thank all of those who have already provided feedback and have provided assistance in testing.

Kieran Jacobsen

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