SIM Security
SIM and eSIM security: subscriber identity at the edge
A SIM or eSIM is a hardware-backed subscriber identity used by mobile networks. It can strengthen authentication — and it can be stolen through port-out fraud.
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SIM
Last reviewed 2026-08-21
Next
Understand what the SIM proves, then stop using SMS as a high-assurance recovery channel where the threat model includes SIM swap.
Request a consultationWho this is for
Banks, carriers, and anyone using phone numbers as authenticators.
Problem
SMS OTP is still treated as a strong second factor.
What to do next
Understand what the SIM proves, then stop using SMS as a high-assurance recovery channel where the threat model includes SIM swap.
Knowledge topics
LibrarySIM Security
Definition
A SIM (and eSIM profile) holds subscriber credentials used to authenticate to a mobile network. It is a form of device/subscriber identity, not a complete human identity.
SIM Security
SIM authentication vs SMS OTP
Network authentication of the SIM is a cryptographic protocol with the operator. SMS one-time codes are messages delivered to a number. They have different threat models. SMS is exposed to SIM swap, SS7 interception in some topologies, and malware that reads messages.
SIM Security
SIM swap and fraud
SIM swap (port-out) moves the number to an attacker-controlled SIM. If banks and email providers trust SMS, the attacker inherits recovery. Detection and operator process controls matter as much as app-layer MFA.
SIM Security
eSIM considerations
eSIM remote provisioning changes logistics; it does not automatically eliminate social-engineering of porting. Profile protection, RSP security, and operator policy still matter.
SIM Security
Limitations
A legitimate SIM on a malware-infected phone can still approve fraud. SIM security is not endpoint security.
SIM Security
Where this meets Keyra
Keyra materials discuss SIM authentication and telecom identity in government and consultation contexts. This page does not publish operator APIs.
Questions
What people ask first.
Plain answers. No product claims that have not been published elsewhere on Keyra.ie.
Does eSIM stop SIM swap?
No. The attack targets control of the number and profile, not only the plastic card.
Is SIM authentication the same as device attestation?
No. SIM authentication proves the subscriber module to the network. Device attestation proves properties of the phone or app environment.