Call Me Maybe: Eavesdropping encrypted LTE calls with ReVoLTE (2020)
6 days ago
- #VoLTE
- #Eavesdropping
- #Security
- VoLTE (Voice over LTE) is a packet-based telephony service integrated into LTE, used by major telecom operators.
- VoLTE encrypts voice data with a stream cipher to prevent keystream reuse, but an implementation flaw allows the ReVoLTE attack.
- ReVoLTE exploits keystream reuse in subsequent calls within one radio connection, enabling eavesdropping on encrypted calls.
- The attack involves recording a target call and a subsequent keystream call to derive the keystream and decrypt the target call.
- Testing revealed 12 out of 15 base stations were vulnerable, mainly in Germany but also other countries.
- Mitigation involves patches provided by vendors, with German operators having applied them by the time of publication.
- An Android app (Mobile Sentinel) was developed to detect vulnerable base stations, requiring root access and a Qualcomm chipset.
- The attack's feasibility was demonstrated in a commercial network using commercial phones and tools like Airscope and ADB.