Thursday, May 13, 2021

Enabling case sensitivity in Windows Folders

I recently discovered that - By default - The Windows Filesystem is case insensitive.

 This is easily testable.



If you require case sensitivity to be enabled in a specific folder, you can run:

fsutil file setCaseSensitiveInfo C:\Reelix\CaseTest enable

You will get informed that it has been enabled.

C:\Reelix\CaseTest>fsutil file setCaseSensitiveInfo C:\Reelix\CaseTest enable
Case sensitive attribute on directory C:\Reelix\CaseTest is enabled.

You can then test the results.

Possible issues

If you get Error: The request is not supported. run

powershell Enable-WindowsOptionalFeature -Online -FeatureName Microsoft-Windows-Subsystem-Linux

And reboot.

If you get Error: Access is denied. then use an administrative terminal.


Tuesday, May 11, 2021

John - Fixing "No OpenCL devices found" for fast GPU cracking

If anyone has tried to do password cracking, they might realize that they generally have 2 options:

1.) Hashcat - Small Range of Hash Formats - Fast Cracking (GPU)
2.) John The Ripper - Large Range of Hash Formats - Slow Cracking (CPU)

What many people don't know is that John can actually do GPU cracking in some instances!

When cracking a hash with John, many people have probably seen something similar to the following recommending the OpenCL variation

Warning: detected hash type "sometype", but the string is also recognized as "sometype-opencl"

But have simply glossed over it, since attempting to use --format:sometype-opencl has simply resulted in a No OpenCL devices found error, and the hash cracks fine (Albeit slowly using only the CPU)

This bug has existed for a long time - This is how to solve it, and get super-fast GPU cracking on John!

1.) In your John folder, open up etc\OpenCL\vendors\nvidia.icd in a text editor
2.) You will see something like c:\Windows\System32\nvopencl.dll
3.) Go to C:\Windows\System32\, and search for nvopencl64.dll - In my case, it was hidden inside a DriverStore folder
4.) Copy the path of it (If you have multiple, simply use the first one), and place the full path inside Johns nvidia.icd, replacing what's already there
5.) Save, and re-run john with the --format:whatever-opencl

Enjoy your fast GPU cracking :)

Tuesday, May 4, 2021

Python3.9 - AttributeError: module 'base64' has no attribute 'decodestring'

Whilst doing a ctf challenge, I needed to brute-force an encrypted private key, so I turned to John and ran the usual
python hash.txt
This time, however, I was greeted with an unfriendly
> AttributeError: module 'base64' has no attribute 'decodestring'
After some searching around, I realized that I could change Line 640 in from
data = base64.decodestring(data)
data = base64.decodebytes(data)
Which solved the issue.

Silly Python3.9 breaking changes :(