Solution to "picoCTF" WebNet1 Challenge

I have finished the WebNet1 Challenge (Hard level) from PicoCTF, and here is the solution if you want to try:

Key Steps to Solve It:

1. Load the PCAP: Open capture.pcap in Wireshark (or use ssldump for decryption).

2. Decrypt the TLS Stream:

   • In Wireshark: Go to Edit > Preferences > Protocols > TLS, and set the RSA key file to picopico.key (under "(Pre)-Master-Secret log filename").
   • Alternatively, use ssldump command-line:

     ssldump -r capture.pcap -k picopico.key -d > decrypted_output.txt
     

     This decrypts the traffic and saves it to a text file.

3. Inspect the Decrypted Traffic:

   • Follow the HTTP stream (right-click a relevant packet > Follow > HTTP Stream in Wireshark).
   • Or search the decrypted_output.txt file for "picoCTF{" using Ctrl+F.

4. Find the Flag: The initial stream shows a fake header like Pico-Flag: picoCTF{this.is.not.your.flag.anymore}—ignore it. Scroll/search further in the decrypted content to locate the real flag hidden in the traffic.

Final Flag

picoCTF{honey.roasted.peanuts}