Tools Required
Wireshark: This is a popular open-source network protocol analyzer used for capturing and inspecting data traveling over a network in real-time.
Solution
We are given the following file:
- talktome.pcap: contains network traffic via USB protocol
Open it with Wireshark
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We see that the packets use the transfer type URB_ISOCHRONOUS, this transfer type is used for transmitting real-time information such as audio and video data, and must be sent at a constant rate.
Next we’ll want to export all the ISO data from this field with tshark
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tshark -r talktome.pcap -T fields -e usb.iso.data | tr -d '\n' | xxd -r -p > audio.raw
Then import the raw data we saved to audio.raw into Audacity and adjust the configuration options to hear the sound clearly.
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You should get an audio that looks like this, listen to it and put each character together to get the complete flag: MetaCTF{4_l1ttl3_b1rd_t0ld_m3}
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