Man-in-the-Middle (MITM)

A Man-in-the-Middle attack places the attacker between two communicating parties, intercepting and possibly modifying their traffic while each side believes it is communicating directly with the other. Telecom-specific MITM scenarios include IMSI catchers on the radio interface and SS7 redirection in the core. Mutual authentication and end-to-end encryption are the principal defences.

Categories: Radio Access NetworkCore NetworkSignaling

Man-in-the-Middle (MITM) in context

The radio access network is the layer where mobile devices attach to the operator's infrastructure. Attacks in this layer include IMSI catching, rogue base stations, downgrade attacks and jamming, and defenses hinge on mutual authentication, integrity-protected signaling and Open RAN supply-chain hygiene.

The mobile core is where subscriber sessions, mobility and policy live. In 4G it is the EPC (MME, HSS, S/PGW); in 5G it is the Service-Based Architecture with AMF, SMF, UPF, AUSF, UDM and the NRF. Core exposure is the difference between a single-subscriber leak and a fleet-wide breach.

To place Man-in-the-Middle (MITM) in the wider telecom-security picture, review MVNO, IPsec, User Plane Security, SBA, S1AP and GTP-U.

Related terms

Related topic hubs

  • Signaling Firewall Unified SS7/Diameter/GTP/SMS signaling firewall framework.
  • IMSI Catcher Rogue base stations, IMSI capture and detection.
  • SS7 Security SS7/MAP/CAP/SCCP attacks and defenses across 2G/3G interconnect.
  • SS7 Firewall GSMA FS.11 category 1/2/3 SS7 message screening at the STP edge.

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