Arm Ltd (ARM Holdings) — 2 prefixes (MA-L)

A MAC address starting with 00:02:F7 or 84:67:9A belongs to Arm Ltd (formerly ARM Holdings plc), the Cambridge, UK-based semiconductor IP company that designs the Arm CPU architecture licensed across billions of embedded, mobile, and IoT devices.

The 00:02:F7 block has a concrete, documented use beyond the bare registration: Arm's Mbed OS embedded platform hardcodes 00:02:F7:F0:00:00 as the fallback default MAC a board returns when it can't read its own unique hardware MAC. A linker symbol-resolution fault (GitHub ARMmbed/mbed-drivers issue #125) caused multiple physical FRDM-K64F boards to ship with this identical duplicate address instead of unique ones — a real duplicate-MAC collision risk on a shared network. The issue is marked resolved, and the Mbed OS platform itself reached end-of-life in July 2026.

The second block, 84:67:9A, registers to "Arm Ltd" at the same Cambridge headquarters but carries no independent device-type corroboration — no forum, GitHub thread, or vendor document names a specific product line using it. Device type for 84:67:9A is Unknown as of an August 2026 search; treat identification from that prefix as company-level only, not product-level.

Arm itself is a well-established company, not a shell registrant: it is publicly traded (NASDAQ: ARM), was majority-owned by SoftBank Group starting in 2016, and its architecture licensees have shipped more than 65 billion SoCs. No malware, trojan, or CVE association was found tied to either OUI as of an August 2026 search.

Device class

00:02:F7 — embedded/IoT boards running Arm Mbed OS, often via its fallback default MAC; 84:67:9A — Unknown, no device corroboration found

Also seen on

Mbed-based boards (e.g. FRDM-K64F) that hit a linker bug and shipped with the duplicate 00:02:F7:F0:00:00 address (GitHub ARMmbed/mbed-drivers#125)

Registry blocks

00:02:F7 (MA-L, org "ARM"), 84:67:9A (MA-L, org "Arm Ltd")

IEEE assignment

2 prefixes → ARM / Arm Ltd, registered Cambridge, GB [Confirmed] — the IEEE MA-L registry 0002F7, the IEEE MA-L registry 84679A

Registry / block size

MA-L (24-bit OUI); 2 IEEE prefixes found for this registrant (00:02:F7, 84:67:9A) [Confirmed] — the IEEE MA-L registry

HQ / country

110 Fulbourn Road, Cambridge, Cambridgeshire, GB CB1 9NJ [Confirmed] — the IEEE MA-L registry 84679A

Company status

active; publicly traded (NASDAQ: ARM); majority owned by SoftBank Group starting 2016 [Confirmed] — https://en.wikipedia.org/wiki/Arm_Holdings

Device types

00:02:F7 — embedded/IoT boards running Arm Mbed OS (used as fallback/default MAC when a board can't read its own unique MAC) [Confirmed] — https://github.com/ARMmbed/mbed-drivers/issues/125; 84:67:9A device type [Unknown] — no corroborating source found as of an August 2026 search

Notable products

Arm CPU architecture, licensed IP; licensees have shipped 65B+ SoCs [Confirmed] — https://www.arm.com/company

Verified sample prefixes (all MA-L)

00:02:F7 (org "ARM"), 84:67:9A (org "Arm Ltd") [Confirmed] — the IEEE MA-L registry

Sub-allocations

none found under either block [Confirmed] — the IEEE MA-S registry (searched), the IEEE MA-M registry (searched)

Registration date

Unknown — IEEE's public OUI data (the IEEE MA-L registry: Registry, Assignment, Organization Name, Organization Address) publishes no assignment/registration date [Confirmed] — the IEEE MA-L registry

Known issue / usage note

00:02:F7:F0:00:00 is hardcoded as the Mbed OS fallback MAC; a linker symbol-resolution fault caused multiple physical FRDM-K64F boards to ship with this identical duplicate address instead of unique ones (issue marked resolved) [Confirmed] — https://github.com/ARMmbed/mbed-drivers/issues/125

Platform lifecycle

Mbed OS reached end-of-life in July 2026; os.mbed.com now redirects to GitHub [Confirmed] — https://blog.adafruit.com/2026/02/02/a-reminder-that-mbed-os-is-end-of-life-july-2026/

Malware/CVE association

none found tied to either OUI as of an August 2026 search [Confirmed]

Related vendors

none found — Arm is an independent semiconductor IP company, not a subsidiary of another OUI holder [Confirmed] — https://www.arm.com/company

Analyst note

An Arm OUI does not indicate the physical device manufacturer — Arm licenses CPU designs to other companies that build hardware and assign their own MACs. 00:02:F7 specifically can indicate Mbed OS firmware still using its default fallback address rather than a manufacturer-assigned unique MAC, which is itself a misconfiguration signal if seen on a shipped product.