Medicare Data Breach Impacts Almost 1 Million Subscribers
Following the Medicare data breach, you can continue to use your existing Medicare card; beneficiaries with compromised Medicare Beneficiary Identifiers will be sent a new card with a new number.

The personal information of more than 900,000 Medicare beneficiaries was exposed during a data breach that occurred between May 27 and May 31, 2023. Information was stolen exploiting a "vulnerability" in the MOVEit software program used by Medicare contractor Wisconsin Physicians Service Insurance Corporation (WPS) to transfer files during the Medicare claims process, according to the Centers for Medicare & Medicaid Services (CMS), the federal agency that manages the Medicare program.
Notification is being sent by CMS and WPS to the almost 947,000 individuals affected that some of their protected health information (PHI) and personally identifiable information (PII) was compromised in the May 2023 security breach.
2023 saw a record breaking number of cyberattacks, with 2,365 breaches and 343,338,964 victims, according to the 2023 ITRC Annual Data Breach report from the Identity Theft Resource Center. Healthcare companies faced the most cyberattacks industry wide with 809 compromises, and the financial sector came in a close second with 744 compromises, according to idtheftcenter.org. Healthcare led all industries in terms of the number of reported compromises in each of the past five (5) years.

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How the breach occurred
WPS provides administrative services to the CMS including the handling of Medicare Part A/B claims. The security breach involved the exploitation of a vulnerability in Progress Software’s MOVEit software, which was used by WPS for transferring files in connection with the services provided to the CMS.
Beginning on May 27, 2023, CL0P Ransomware Gang, also known as TA505, began exploiting a previously unknown vulnerability in Progress Software's managed file transfer (MFT) solution known as MOVEit Transfer. Internet-facing MOVEit Transfer web applications were infected with a web shell named LEMURLOOT, which was then used to steal data from underlying MOVEit Transfer databases, according to the Cybersecurity and Infrastructure Security Agency (CISA).
What information was involved?
- Name
- Social Security Number or Individual Taxpayer Identification Number
- Date of Birth
- Mailing Address
- Gender
- Hospital Account Number
- Dates of Service
- Medicare Beneficiary Identifier (MBI) and/or Health Insurance Claim Number
What is a Medicare Beneficiary Identifier (MBI)?
The Medicare Access and CHIP Reauthorization Act (MACRA) of 2015, required the removal of Social Security numbers from Medicare cards. By April 2019, Medicare Beneficiary Identifiers (MBIs) replaced Social Security numbers on Medicare cards.
On a Medicare card, an MBI will appear similar to this: 1EG4-TE5-MK73. The second, fifth, eighth, and ninth characters are always letters while the first, fourth, seventh, tenth, and eleventh characters are always numbers. There isn't a standard for the third or sixth characters.
The CMS press release said they "are not aware of any reports of identity fraud or improper use of your information as a direct result of this incident." They do advise that you can continue to use your current card to receive services. If CMS determines your MBI was compromised as a result of the breach, a new Medicare card with a new new number will be issued to you. CMS will mail the new card to your address in the coming weeks.
After you get your new card, CMS says you should:
- Follow the instructions in the letter that comes with your new card
- Destroy your old Medicare card
- Inform your providers that you have a new Medicare number
What can you do if you were impacted by the data breach?
Yogi Berra sums up how I feel about giving tips to protect your data — "It's like déjà vu all over again." I hope these tips will now become a habit instead of a defensive measure. Your information is valuable and there is no shortage of bad actors scheming to steal it.
Here are five tips for protecting your identity and data:
- Sign up for 24/7 credit monitoring and activate two-factor authentication
- Never respond to unsolicited requests for information
- Review credit card, bank accounts and loans on a regular basis
- Place a free fraud alert on your credit file. A fraud alert tells creditors to contact you before they open any new accounts or change your existing accounts.
- Freeze your three primary credit reports. In this context, "freezing" means that you prohibit your credit reports from being accessed by most third parties. In return for a fee you get a PIN from the credit bureaus. This PIN acts as an additional key and it must be given in order for your credit reports to be accessed and used to open accounts or obtain loans
Bottom line
The Medicare data breach comes on the heels of the NDP and Change Healthcare breaches. It should prompt everyone to be vigilant about checking bank accounts, loan and credit card accounts and credit reports regularly. These breaches are a fact of life and we have to take regular, affirmative steps to guard against them. It is no longer enough to make inquiries after something happens. A pro-active stance is the best offense and defense when it comes to cybersecurity.
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Donna joined Kiplinger as a personal finance writer in 2023. She spent more than a decade as the contributing editor of J.K.Lasser's Your Income Tax Guide and edited state specific legal treatises at ALM Media. She has shared her expertise as a guest on Bloomberg, CNN, Fox, NPR, CNBC and many other media outlets around the nation. She is a graduate of Brooklyn Law School and the University at Buffalo.
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