GSMantics Writeup

In the extract we have :

 $ sudo grgsm_scanner --args="bladerf=0"
 ARFCN: 10, Freq: 937.0M, CID: 11530, LAC: 26530, MCC: 208, MNC: 10, Pwr: -28

Knowing CID (Cell ID), LAC (Location Area Code), MCC (Mobile Country Code), MNC (Mobile Network Code) we can use OpenCellD to search for the exact tower (the closest to the cellphone at the time)

We now know it's in France in the "Die" commune.

For the operator, knowing it's in France we can lookup for a list of MNC corresponding to it's operator using for instance this website

And find that the MNC = 10 corresponds to the "SFR" operator. We then have the flag