NSRL Query from the Command Line

In digital forensics, we’re frequently trying to separate the signal from the noise. When examining operating systems – including mobile, it can be helpful to know what files came with the operating system. By filtering those out we can concentrate on what’s new on the device as we start looking for activity.

The National Software Reference Library (NSRL) is designed to collect software from various sources and incorporate file profiles computed from this software into a Reference Data Set (RDS) of information. The RDS can be used by law enforcement, government, and industry organizations to review files on a computer by matching file profiles in the RDS. This will help alleviate much of the effort involved in determining which files are important as evidence on computers or file systems that have been seized as part of criminal investigations.


Recently I came across a site that, among other capabilities, has the option of doing an NSRL lookup using curl from the command line.

Me being Mr. PowerShell I wanted to see what the syntax would be to do the same lookup with PowerShell. So where did I turn? No, not to Jeffrey Snover. I went to ChatGPT. I’d heard quite about how services like these, while not trustworthy for anything of historical accuracy, are pretty good at translating code.

The original syntax:

curl -X 'GET' \
  'https://hashlookup.circl.lu/lookup/sha1/09510d698f3202cac1bb101e1f3472d3fa399128' \
  -H 'accept: application/json'

Sure enough it returned functional code to do the same operation in PowerShell. What I really appreciated though is the detailed information beneath that explains the parallel functions between the two, and what the different values represent. I could see myself using ‘explain this code to me’ in the future.

PowerShell NSLR Query Syntax:

Invoke-RestMethod -Uri 'https://hashlookup.circl.lu/lookup/sha1/3f64c98f22da277a07cab248c44c56eedb796a81' -Headers @{accept='application/json'} -Method GET

I also asked it to convert the curl command to Python which it handled equally well, and once again the same level of explanation of what’s going on beneath the code.

Python NSRL Query Syntax:

import requests
response = requests.get('https://hashlookup.circl.lu/lookup/sha1/09510d698f3202cac1bb101e1f3472d3fa399128', headers={'accept': 'application/json'})

Curl script & output

Python script & output

PowerShell script & output

Of the three, I prefer the output of the PowerShell command as the output is the most readable. In the screenshot above, four queries were run. For the first two there wasn’t a matching hash detected, so we can’t confirm whether those were included with the operating system. For the second two queries, which happen to be for executable names that are frequently misused by bad actors, we see that the hashes queried do match the published NSRL.

VS Code Interactive Notebooks

I’ve been using Visual Studio Code as my go to editor for PowerShell, JSON, plain text, and recently even a dash of Python. VS Code is very extensible and much like the App Stores we’ve come to know, there’s an extension marketplace to broaden its capabilites.

One of my favorite extensions is the .NET Interactive Notebooks. Notebooks combine markdown text and code snippets that you can run right within the notebook. This can be very useful for designing playbooks for a SOC or Junior Analyst to execute as you can describe and provide guidance on how to utilize the code functions.

An easy way to get started with Interactive Notebooks is to create a “Quick Codes” notebook. Title it as you choose. For this particular notebook, I’ve got a number of commands saved that I may reference semi-frequently, but due to limited space in my mind palace I wind up googling them anyway, even if it’s googling my own site.

Trying to remember a specific PowerShell syntax

Note before installing:
As your scripts and notebooks develop, there is a likelihood that you will want to run some either as Administrator or using another user credential. One way to do so simply launch VS code (right click) as Admin, or use the Run As feature when you launch the application.

  1. Download and install VS Code.
    Note – as you may be running this with multiple credentials, the “System” installer is recommended.
  2. Install the latest .Net SDK
  3. When inside VS code, bring up the Extensions view by clicking on the Extensions icon in the Activity Bar on the side of VS Code, or the View: Extensions command (Ctrl+Shift+X).
    Search for “interactive”
    Select .NET Interactive Notebooks and choose install

Once everything is all set, relaunch VS Code.

Hit Ctrl+Shift+P and select .NET Interactive – Create New Blank Notebook.

That’s it. Now start adding blocks for text and code. You can use simple markup codes for Heading (#), Heading 2 (##), Heading 3 (###), etc.

To execute the code snippet, just click on the small ‘play’ arrow to the left.

Do you have any novel uses for Interactive Notebooks? If so, please share in the comments area.