miscmeplx


Miscmeplx

In miscmeplx we are given a file to download which comes to us as download_misc_intro.zip

After running unzip the file is now recording.sr

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recording.sr


Next I looked at the recording.sr file with hexedit and the magic number headers identified it as a PK zip file.

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So I unzipped this file as well.

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metadata


Next I looked at the file called metadata inside was what type of file this is. It is a logic probe recording from a program called sigrok. This was much more helpful than when googling what is a .sr file that pointed me to Sega Genesis console games.

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sigrok download


I then searched for sigrok 0.5.2 and landed on their download page. The program is available across multiple platforms in GUI or CLI.

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setup and hex values


Initially after opening up the recording.sr file with sigrok it didn't look like much except for in leads D6 and D7 there was a little blip on the right. I noticed a selection tool and zoom function so I selected this blip and began zooming in.

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I found this YouTube video as an intro to sigrok and used it to isolate the D6 and D7 leads.

https://www.youtube.com/watch?v=z8Tdz7eQ8n4

Also, how to apply the logic interpreter. This evaluates the signal to what looks like hex values.

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data manipulation


Right clicking on the I2C Address/data and selecting "Export all annotations" I saved the data to a file called hexstream.txt

The output of the hexstream.txt file:

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Copied and pasted this into a linux machine to manipulate the data.

Cat hexstream | grep write: | cut -f 6 -d " " |tr "\n" " " | tee output

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flag reveal


I then put this output into a hex to ascii converter. I tried using xxd -r but it would break before finishing the conversion.

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