Masimo Corporation is a US medical-device maker (non-invasive patient monitoring — pulse oximeters, multi-parameter bedside monitors, and hospital connectivity platforms) headquartered at 52 Discovery, Irvine, CA, and the registry snapshot enumerates eight IEEE assignments under its name: seven MA-L (24-bit) blocks and one MA-M (28-bit) block, with no MA-S blocks. Two earlier MA-L assignments (08:09:B6 and 50:4A:5E) carry an older registrant address — 40 Parker, Irvine, CA — because the registry records the address that was current when each block was assigned, not a single present-day address. Operationally these OUIs land on networked clinical gear: the Root patient-monitoring hub, the Rad-97 bedside oximeter with enterprise Wi-Fi, tetherless Radius PPG/Radius-7 wearables, and the Iris Gateway that bridges devices to EMR/EHR systems over HL7. That places Masimo squarely in the Internet of Medical Things (IoMT) attack surface, and a confirmed April 2025 cyberattack on Masimo's on-premise network (manufacturing disrupted; cloud systems unaffected; vector unattributed) is a reminder that connected medical endpoints are worth segmenting. For triage, a Masimo OUI on a globally-administered address identifies clinical patient-monitoring hardware that typically belongs on an isolated medical-device VLAN rather than a general user network. As with every OUI entry, no registration date is reported: IEEE publishes none, and any third-party "date registered" value is a database artifact.
- IEEE assignment
- 8 prefixes → "Masimo Corporation" (recorded once as "Masimo Corp"), 7 MA-L + 1 MA-M, registered Irvine, CA, US [Confirmed] — IEEE oui.csv / mam.csv (cached registry snapshot)
- Registry / block size
- MA-L (24-bit) predominant — 7 blocks; plus 1 MA-M (28-bit) block; no MA-S (36-bit) blocks found [Confirmed] — IEEE oui.csv, mam.csv, oui36.csv (no oui36 match). NOTE: IEEE's public OUI data publishes NO assignment/registration date (the CSV columns are only Registry, Assignment, Organization Name, Organization Address); any "date registered" from third-party tools (e.g. maclookup.app) is a database artifact, not an IEEE fact.
- HQ / country
- 52 Discovery, Irvine, CA 92618, US (primary registry address); earlier blocks 08:09:B6 and 50:4A:5E carry 40 Parker, Irvine, CA 92618, US. Country: US [Confirmed] — IEEE registry snapshot
- Company status
- active; publicly traded (Nasdaq: MASI); founded 1989 [Confirmed] — masimo.com, en.wikipedia.org/wiki/Masimo
- Device types
- networked clinical patient monitors (Root), bedside pulse oximeters with enterprise Wi-Fi (Rad-97), tetherless/wearable oximeters (Radius PPG, Radius-7), medical-device connectivity gateways (Iris Gateway), remote-monitoring servers (Patient SafetyNet) [Confirmed] — masimo.com, healthmanagement.org
- Notable products
- Root patient-monitoring hub, Iris Gateway (HL7/EMR integration), Patient SafetyNet remote monitoring, Radius PPG wearable oximeter, Masimo SafetyNet telehealth
- Verified MA-L prefixes (Masimo Corporation)
- E0:C2:B7, C8:8B:E8, 88:09:AF, C8:16:A5, 08:09:B6, 50:4A:5E, B8:10:D4 [Confirmed] — IEEE oui.csv (cached snapshot)
- Verified MA-M prefix
- C0:22:F1:E (28-bit MA-M block) [Confirmed] — IEEE mam.csv (cached snapshot)
- Connectivity
- devices reach hospital networks over IEEE 802.11 a/b/g Wi-Fi and Ethernet; the Iris Gateway / Rad-97 connect through hospital access points and forward HL7 messages to EMR systems; Masimo integrated Imprivata authentication into its Root and Iris platforms for secure clinical access [Confirmed] — healthmanagement.org, investor.masimo.com
- Security context
- confirmed cyberattack on or about 2025-04-27 hit Masimo's on-premise network — manufacturing capacity reduced and order fulfillment delayed; cloud systems reported unaffected; attack type/vector unattributed and no group claimed responsibility. No CISA ICS-CERT (ICSMA) advisory specific to Masimo Root or Iris Gateway was found in public sources. Masimo publishes a Coordinated Vulnerability Disclosure (CVD) policy. [Confirmed for the breach event and CVD policy; absence of an ICSMA advisory is "none found," not a guarantee none exists] — cybersecuritydive.com, cyberinsider.com, masimo.com (CVD statement)
- Data-quality note
- a third-party MAC database (maclookup.app) lists Masimo with 7 allocations and shows only 6 MA-L blocks (omitting one MA-L the cached IEEE snapshot contains); the registry CSV enumeration of 7 MA-L + 1 MA-M = 8 is treated as authoritative for assignment counting. Any "date registered" on that source (e.g. 2012 for 50:4A:5E) is a third-party artifact, not an IEEE date. [Likely — single third-party source for the discrepancy] — maclookup.app/vendors/masimo-corporation
- Related vendors
- none material (independent medical-device manufacturer)
- Analyst note
- a Masimo OUI on a globally-administered address identifies clinical patient-monitoring hardware; standard IoMT practice is to place such devices on an isolated medical-device VLAN with Zero-Trust/segmentation controls. OUI alone does not confirm device identity — pair with network context.