RANAP (Radio Access Network Application Part)

Also known as: Radio Access Network Application Part

RANAP is the 3GPP signalling protocol between the UTRAN RNC and the 3G core (MSC or SGSN) over the Iu interface (TS 25.413). It handles UE context, RAB assignment, paging, security mode control and relocation. RANAP is typically carried over SS7 SCCP/MTP or SIGTRAN M3UA, which makes 3G core interfaces reachable from SS7 attackers when Iu links are exposed.

Categories: Radio Access NetworkCore NetworkSignaling

RANAP 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 RANAP in the wider telecom-security picture, review S1AP, IPsec, Patch Management, 5G Reference Points, IMS-AKA and N2.

Related terms

Equipment

RAN controllers (BSC, RNC)

Related topic hubs

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