1753CTF 2025 - FORENSIC/OSINT - Where did he go?

Challenge

Writeup

We receive a file: where-did-he-go.zip. Inside, there’s a mysterious file: GPS_LA.sal.

A quick search reveals that we need to install specific software to open it, such as Logic 2.4.22.

We open the file in Logic, go to Analyzers, select I2C, and set SDA to channel 0 and SCL to channel 1.

Then we export the data to CSV.

After splitting the columns, we get the following bytes:

0x00 0x00 0x24 0x47 0x50 0x47 0x4C 0x4C 0x2C 0x35 0x30 0x32 0x36 0x2E 0x36 0x30 0x38 0x32 0x2C 0x4E 0x2C 0x30 0x31 0x38 0x35 0x31 0x2E 0x34 0x36 0x38 0x35 0x2C 0x45 0x2C 0x31 0x32 0x33 0x35 0x31 0x39 0x2C 0x41 0x2A 0x32 0x38

Converted from hex:

$GPGLL,5026.6082,N,01851.4685,E,123519,A*28

We then convert the coordinates to Google Maps format:

Latitude: 50.44347

Longitude: 18.85781

Searching for a language school near that location reveals:

GOLDEN GATE Szkoła Języka Angielskiego

The flag is: 1753c{golden_gate}