DidierStevensSuite VS CyberChef

Didier Stevens is a famous security researcher, but his instructions on how to scan pdf's require the terminal & many commands. I am hostile to this in general as I think it can all be implemented in a simple one click scan tool, instead. Which is what I am looking for. Here are all his relevant links & antivirus/anti-malware projects & tutorials: https://github.com/DidierStevens/DidierStevensSuite

This tool was built to fill a gap in the PDF assessment landscape. Didier Stevens's pdfid.py and pdf-parser.py are still the best game in town when it comes to PDF analysis tools but they lack in the visualization department and also don't give you much to work with as far as giving you a data model you can write your own code around. Peepdf seemed promising but turned out to be in a buggy, out of date, and more or less unfixable state. And neither of them offered much in the way of tooling for embedded binary analysis. Thus I felt the world might be slightly improved if I strung together a couple of more stable/well known/actively maintained open source projects (AnyTree, PyPDF2, and Rich) into this tool.

OK then. So I won't accidentally miss any, I've made a little script to find them. It uses oledump.py which, as the name suggests is a Python script to dump OLE files. Here is oledump.py on Github. Excel stores its macros in an OLE file names xl/vbaProject.bin inside the .xlsm file, and oledump knows how to find that, list the streams in them, and extract the macros from the streams that contain them.

You can install emldump and programmatically extract all attachments

Didier Stevens Suite - He has a tool for everything.

Then we take the encrypted text and use CyberChef to decrypt it.

Let's go to CyberChef and insert our pieces of evidence.

A parameter was changed from '2AMBCgIQBg' to 'CgIIAdgDAQ%3D%3D' which is just the correct base64 encoding they should have been using the entire time.

I don't think this was a hostile action by Google, I think someone just added better input validation for security reasons and it accidently broke the bad requests they were sending.

https://gchq.github.io/CyberChef/#recipe=URL_Decode()From_Ba...

❗This is indeed the flag, but the text is encrypted with Base64. Usually, the presence of padding character "=" indicates that's Base64 type of encoding (but that's only one of the hints). To decrypt it, we can use CyberChef. Copy-paste the text and we either:

It uses a combination of magic bytes (like the `file` command), entropy analysis and character frequency detection to determine whether an output is likely to be of interest to the user.

The file type mechanism is written here[0]. There's a list of all signatures we detect here[1].

[0] https://github.com/gchq/CyberChef/blob/master/src/core/lib/F...

I think this can be deciphered using CyberChef...