Internally, Active Directory stores all passwords as so-called NTLM Hashes. There are a number of security-analysis tools that can read and dump these hashes.
While there fortunately is no feasible way of decrypting these hashes and retrieving the original passwords, you can take a (known) password and turn it into an NTLM hash yourself. This is the fundamental procedure of dictionary attacks: they take long lists of…
Here’s a fun PowerShell script that you can use to create a simple multi-channel chat room. All you need is a network share where everyone has read and write permissions.
The chat is file-based and makes use of PowerShell’s ability to monitor files for changes. So essentially, each chat channel is a text file, and whenever someone wants to “say” something, a text line is added to the file. Anyone connected to the…
In previous tips, we already talked about services such as haveIbeenpwned.com. They harvest leaked passwords from previous hacker attacks so you can check whether your password has been compromised and is likely to be included in future dictionary attacks.
Below, you find two useful functions: Test-Password asks for a SecureString so when you get prompted, your input is masked. Convert-SecureStringToText then converts…
It can be very useful to be able to convert an encrypted SecureString back to a plain text. This way, for example, you can use PowerShell’s “masked input” features. Simply ask for a SecureString, and PowerShell takes care of masking the user input. Next, take the SecureString and turn it into a plain text so you can use it internally for whatever you like:
function Convert-SecureStringToText { par…
If your script requires external binary resources such as picture files or DLLs, you can of course ship them together with your script. You could, however, also embed these binaries as text in your script files:
This way, your script can then read the Base64-encoded binaries from a text variable, turn the data back into bytes, and write them back…
In October 2018, a Windows 10 update added built-in SSH support to Windows 10. From now on, Windows 10 ships with a command-line tool called “ssh”. You can use it from within PowerShell to connect to other devices (including IoT, Raspberry Pi, etc) without the need for 3rd party tools:
PS> ssh usage: ssh [-46AaCfGgKkMNnqsTtVvXxYy] [-B bind_interface] [-b bind_address] [-c cipher_spec] [-D [bind_address…
In the previous tip we illustrated how you can download a PowerShell script which automatically downloads the latest version of PowerShell Core.
This script supports a number of parameters. By default, it fetches the latest (stable) production version. If you’d like to play with the latest version including preview versions, use the -Preview parameter. And, if you’d like to install it using an MSI package, add -MSI.…
As you probably know, Windows PowerShell (the one shipping in Windows) is done, and all efforts go into development of the new cross-platform PowerShell Core. This new PowerShell version is not (yet) shipping out-of-the-box in Windows, so in order to play with it, you need to download it manually.
Fortunately, there is a script that does the heavy-lifting for you. This is how you can download the script source code:
Here is a one-liner that retrieves your current public IP address:
PS> Invoke-RestMethod -Uri http://ipinfo.io ip : 87.153.224.209 hostname : p5799e0d1.dip0.t-ipconnect.de city : Hannover region : Lower Saxony country : DE loc : 52.3705,9.7332 org : AS3320 Deutsche Telekom AG postal : 30159 timezone : Europe/Berlin readme : https://ipinfo.io/missingauth
ReTweet this Tip!
PowerShell comes with a powerful yet simple way of monitoring file changes. Let’s assume you have a log file that changes every now and then. This would be a PowerShell script that monitors the log file for changes, and whenever a change occurs, executes some code:
# make sure this points to a log file $Path = '\\myserver\report2.txt' Get-Content -Path $Path -Tail 0 -Wait | ForEach-Object { "Detected…
Typically, key press detection is supported only in true console windows, so this approach won’t work for the PowerShell ISE and other PowerShell hosts.
However, PowerShell can borrow a type from the Windows Presentation Foundation that can check the state of any key. This way, it becomes trivial to implement an “abort” key that works in any PowerShell script, whether it runs in the console, Visual Studio Code,…
In Windows 10 and Windows Server 2016, PowerShell can access storage reliability data so you can find out whether there is something wrong with one of the attached storage drives. This requires Administrator privileges to execute:
PS> Get-PhysicalDisk | Get-StorageReliabilityCounter DeviceId Temperature ReadErrorsUncorrected Wear PowerOnHours -------- ----------- --------------------- ---- ------------ 0 …
PowerShell can execute internal PowerShell commands and also regular console commands, so it’s not a bad thing to continue to use console commands for proven tasks.
For example, if you’d like to reset your winsocks, this would be a reliable solution:
#requires -RunAsAdministrator netsh winsock reset netsh int ip reset
Note that this code requires Administrator privileges, and may require a system restart…
This is part 5 of our mini-series about the awesome and free “ImportExcel” PowerShell module by Doug Finke. Make sure you install the module before you play with this tip:
PS> Install-Module -Name ImportExcel -Scope CurrentUser -Force
In part 4, we looked at misinterpreted data due to arrays found in the input data. As you have seen, you simply need to convert arrays to strings using the -join operator…
This is part 4 of our mini-series about the awesome and free “ImportExcel” PowerShell module by Doug Finke. Make sure you install the module before you play with this tip:
In part 3, we looked at misinterpreted data due to automatic formula conversion, and examined your options to post-process individual cell formats. Let’s examine issues…
This is part 3 of our mini-series about the awesome and free “ImportExcel” PowerShell module by Doug Finke. Make sure you install the module before you play with this tip:
In part 2, we looked at misinterpreted data due to automatic number conversion. Another issue can occur when raw data “looks like” Excel formulas in which case they are…
This is part 2 of our mini-series about the awesome and free “ImportExcel” PowerShell module by Doug Finke. Make sure you install the module before you play with this tip:
When you export data to Excel files, you may sometimes encounter data that is misinterpreted by Excel. For example, often phone numbers are misinterpreted as numeric…
Doug Finke has created an awesome PowerShell module called ImportExcel which comes with all the commands you need to import and export data from and to Microsoft Excel. It does not require Office to be installed.
We can’t cover all the richness this module delivers, but in this tip, we’d like to provide you with the basics to get it up and running, and in follow-up tips we’ll deal about some formatting tricks.…
In the previous example we looked at how numeric HTTP response codes can automatically be converted to descriptive text, simply by converting them to the type System.Net.HttpStatusCode.
PS> [System.Net.HttpStatusCode]500 InternalServerError
This works because System.Net.HttpStatusCode is a so-called “enumeration” and acts like a “lookup table”. You can easily dump all members of an enumeration, and for example…
In the previous example we created a small PowerShell function that checks web site availability, and as part of the test results, a HTTP response code was returned. Let’s check out how this numeric code can be easily converted into a meaningful text message.
Here is the function again that tests web sites:
function Test-Url { param ( [Parameter(Mandatory,ValueFromPipeline)] [string] $Url ) …
When a web site is unavailable, often the question is whether it’s you, or whether the web site is generally down for everyone else, too. PowerShell can ask a web service to check web site availability for you. Here is a simple wrapper function:
function Test-Url { param ( [Parameter(Mandatory,ValueFromPipeline)] [string] $Url ) Add-Type -AssemblyName System.Web $check = "https://isitdown…
Accessing RESTful web services is trivial for PowerShell: simply send your input data to a public web service, and receive the results.
Here are three PowerShell functions designed to each do a numeric conversion:
function Convert-InchToCentimeter { param ( [Parameter(Mandatory)] [Double] $Inch ) [Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12 $url = 'https://ucum…
PowerShell can validate AD username and passwords against the Active Directory:
Add-Type -AssemblyName System.DirectoryServices.AccountManagement $account = New-Object System.DirectoryServices.AccountManagement.PrincipalContext([DirectoryServices.AccountManagement.ContextType]::Domain, $env:userdomain) $account.ValidateCredentials('user12', 'topSecret')
Note that this approach is for diagnostic purposes…
If you’d like to add an incrementing number to your output, here is a simple way:
Get-Process | Select-Object -Property '#', ProcessName, CPU -First 10 | ForEach-Object -begin { $i = 0} -process { $i++ $_.'#' = $i $_ } -end {}
Select-Object adds a new property called “#”, and ForEach-Object adds an auto-incrementing number to it. The result looks similar to this:
If you ever write PowerShell functions that need to accept sensitive input such as passwords, make sure you allow users to submit SecureString input. If you accept passwords via clear text, there is a substantial risk that others may see the password while being entered, or (even worse) that the password is logged and later can be found in dump files.
Here is a simple framework that illustrates how you can achieve safe…