We covered another hardware hacking challenge from hackthebox where we analyzed an signal file captured using software-defined radio. We used software-defined radio analysis tools such as rtl_433 and inspectrum to decode and extract relevant data from the data capture. This led to the extraction of hex data that when decoded yielded the challenge flag.

Challenge Description

We have found the garage where some cyber criminals have all their stuff using an SDR device (software defined radio) we captured the signal from the remote key that opens the garage now. Can you help us to analyze it?

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Video Transcript

We are given a floating point sample file with the extension .cf32 which represents a data capture file holding signal information captured by a software-defined radio.
Now this kind of files can be analyzed using a program designated for analyzing software-defined radio data.We’re going to use rtl_433 which is more than just a tool used to analyze signals. It’s also tool used for receiving data so as you see the description says generic data receiver and there are many options provided by the tool that make it more than just a tool to analyze data captures.
We can use rtl_433 -h command to retrieve the help menu and we can use rtl_433 signalfile.cf33 -A to decode a data capture file. The hex value we found we can feed it to cyberchef and decode it to extract the challenge flag.

Another method of analyzing signal data captured by software-defined radio is using inspectrum which is is a tool for analyzing captured signals, primarily from software-defined radio receivers. Now inspectrum is more geared towards viewing the signal and analyzing the frequencies of the signal more than just viewing the raw data in the captures as in the case of rtl_433.

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