TKTOF Writeups - Winter Wanderer

This challenge is a pure investigative OSINT challenge, where you aren't given much information but have to narrow down your guesses to a mere few.
The description says:

In December, a company got its database leaked by a lone wanderer. This threat actor is known for not leaving a single footstep visible in the snow, and always disappears at night. However, this time, someone in the company tried to follow him. He lived to tell the tale to us, but he said that his head "felt heavy" when he was chasing him. Moreover, his pocket had a weird picture and a note: "he's dangerous, he works with-". The note looks like it was written on a rush, and the picture was very blurry.

Going through this description, there are three key informations we should extract in order to narrow down our guesses:
- First, it is clear that nothing in this description is tied to cybersecurity (excluding maybe the word "threat actor"), and since this is a CTF, it's safe to assume that the "organization" in question is a hacker group.
- Second, the photo is the attachment given to you, and it's a photo which hints at Sevkabel Port in Russia. This indicates that the group's in Russia.
- Third, in the attachment itself, you'll find that the image's author goes by the name "Phishermann", meaning that the organization in question is related to a phishing attack of some sort
(forth, but it's too vague: if you want to narrow it down more, only one person was attacked, which I've put in to indicate spearphishing in particular).

Using all these hints, a small search in the MITRE ATT&CK platform will give you a hacker group's name which is kind of similar to the challenge name's: Winter Vivern (or Winter Wyvern) (G1035 on MITRE ATT&CK).

Flag: CODE{WINTER_VIVERN}

Author's note: The challenge was made to be a little tough in order to simulate how actual detectives find some of the most hidden organizations through a single photo/image. I could've made this challenge a little easier but I wanted to make it a tricky one for AI models to solve, and one which can require human intellect and deductive skills from vague hints. Hope you've enjoyed this challenge!