Hackvent 2024: Day 23

[HV24.23] Santa's Packet Analyser

Santa was invited to an Open Source conference in fall to talk about his newest development on “elfilter – a packet inspector to balance elf load”. Due to the sensitive nature of the talk, it was only open to a very select audience. Nonetheless, he came back with a nice scarf. The elfs suspect there might be a message behind the pattern.

Wrap the text of the flag into HV24{} before submitting it. Make sure that the rest of the text is all in lowercase.
Analyze the image and get the flag.
Flag format: HV24{}
sha256sum of the image: 3393c3a1e30ab0420312488d8075a24e4607fea4bc642f14bd6e8e12a6a5ec6f
Source to the BSD beastie for attribution: https://github.com/freebsd/freebsd-src/tree/main/share/examples/BSD_daemon

This challenge was written by brp64. Maybe the b stands for BSD.

Image:

Solution

In this challenge, we are given an odd-looking image of something that looks like a barcode. We do not initially know what this is, but we try to find similar-looking images online. Reverse image searches do not yield any useful results. Eventually, after various online attempts, we search for stemline language, which shows some results for the Ogham language. The Ogham language appears identical to the pattern in our image.

We find this image of an Ogham alphabet:

Using this, we manually decode our message and get:

SANTAFILTERSPACQETS

We assume the Q here is incorrect and should instead be a K to give us SANTAFILTERSPACKETS. Finally, as instructed in the challenge description, we substitute this into the flag format and lowercase the contents to get our daily flag.

Flag:

HV24{santafilterspackets}

Bonus Hidden

This challenge also contained the solution to: [HV24.HE] Grinch's Secret