e-Jornadas 2020 CTF: write-up

Recently I participated in “e-jornadas 2020 CTF” here is how I solved some of the challenges.

Rotate away

we have been given the following string

rxms{xqfedafmfqftueftuzs}

So it looks like Caesar cipher so let’s decode it using the decode.fr website.

we got our flag.

Flag : flag{letsrotatethisthing}

Not so strong covert channel

So we have been given one pcap file. so let’s open it in Wireshark.

This pcap file contains 446 packets.

The first thing I did was sorted packets according to Protocols.

Then I opened the first TCP packet like this.

Let’s follow TCP Stream.

we got output like this,

So nothing interesting here so let’s move on to the next stream. (bottom right corner we need to change the value of Stream from 0 to 1.

Here we got our flag.

Flag: flag{long_live_lalaland}

Cooperation is key

Again we got the pcap file. So let’s open it in Wireshark.

This time we just got 156 packets.

Before opening any packets let's first try to see if this pcap file gives any files via Export.

Selecting Export Objects → HTTP.

So we have 3 files let’s save it.

THE last PNG file looks interesting so, let’s open that first.

Flag: flag{red_is_cooler}

Thank you for reading.