SHA2017 - Junior CTF - Captured Mail - Pcap

Problem

We intercepted this mail message. Can you open the attachment?

capturedmail.pcap f31a3916b3de4d880db104d6a7bc1b7e

Solution

Using Wireshark's follow tcp stream returns a string representing a zip file

UEsDBBQAAAAIAIy53UoyFb1+UwAAAFgAAAAIABwAZmxhZy50eHRVVAkAAzhtVVk4bVVZdXgLAAEE 6AMAAAToAwAAFclLCoAgEADQfaeYA0QQMaOz7iSjjB8QBbVVdPdq+Xhnq7HLvIrM3OpYYSaFUCRC aP1DHuCTlKI1Knz4694dsrHGGELrxAuzV8JDAgVBJn225QVQSwECHgMUAAAACACMud1KMhW9flMA AABYAAAACAAYAAAAAAABAAAApIEAAAAAZmxhZy50eHRVVAUAAzhtVVl1eAsAAQToAwAABOgDAABQ SwUGAAAAAAEAAQBOAAAAlQAAAAAA

Saving the string to an empty file and unzipping returns the flag.

FLAG: flag{1b5978777658baca99ce653af6fa596e}