GSM5_IMSICATCHER_HALFMITM_SPOOFING-REAL-OPERATOR-BTS

Half MITM = Fake BTS only

Protocol flow

Why it is possible ?

  • Fake base station with open ciphering named A5/0, and spoof real operator network; the network could be GSM(sms, call), and GPRS, EDGE

Attack limitations and advantages

  • local attack but could be targeting (to find local victim)
  • victim couldn't be reached on the real network (indeed call and sms)
  • could be detectable with rooted phone and application like imsi-catcher detector, snoopsnitch because of open network

Devices

  • USRP

Pratices

  • Install DragonOS 29 or 30 for USRP
  • Create fake bts with more specifications demos pdf_en pdf_fr
  • Open ciphering (A5/0)
  • Configure power as big as possible or use power amplifier
  • MCC, MNC, band, arfcn, short name and long name like the operator (use network signal guru to find the configuration)
  • LAC not like the operator (the phone think it makes handover)
  • Use jamming or redirection attack for more advanced attack
  • creating selective denied of service attack (imsi) by using lur (location update reject) demos pdf

Proposition of solution :

In openbsc.cfg

network country code 001
mobile network code 1
short name dragonOS
long name dragonOS
band GSM1900
arfcn 526
nominal power 100

In osmo-bts.cfg

band 1900

For denied of service change location update reject cause, the default cause is numbered 13

location updating reject cause 13