Breach filing
ArchivedAon PLC: 129,682 individuals, May 2022.
Aon PLC reported a breach of unsecured protected health information to the HHS Office for Civil Rights on 26 May 2022. The filing records the organisation as a business associate in Illinois and lists 129,682 individuals affected, which makes it the 34th largest of the 358 Illinois filings on the register and the 81st largest of the 718 filings submitted nationally in 2022. Among the 22 Illinois filings made in 2022 it ranks 7th.
Individuals affected
129,682
As reported to HHS
Modelled cost (IBM 2025)
$20.7M
Upper bound, method shown
Rank in IL
34th
of 358 Illinois filings
Rank in 2022
81st
of 718 filings nationally
Section F.1 / The filing
As posted by HHS OCR
Every value below is the portal's own field for this filing, plus its rank within the register.
- Covered entity type
- Business Associate
- Individuals affected
- 129,682
- Breach submission date
- 26 May 2022
- Submission year
- 2022
- Type of breach
- Hacking/IT Incident
- Location of breached information
- Network Server
- Business associate present
- Yes
- State
- Illinois (IL)
- Portal status
- listed in the HHS OCR breach portal archive
- Rank in Illinois by size
- 34th of 358
- Rank in 2022 nationally
- 81st of 718
- Illinois median filing
- 3,403 individuals
- Register id (derived)
- IL-20220526-aon
Section F.2 / In context
Where this filing sits in Illinois and in 2022
OCR classifies the incident as a hacking or IT incident, with the breached information held in a network server. Hacking/IT Incident is the type recorded on 201 of the 358 Illinois filings (56%) and on 79% of all filings submitted in 2022. Network Server appears on 43% of Illinois filings.
A business associate is recorded as present on the filing, as it is on 34% of Illinois filings. At 129,682 individuals the breach is 38 times the Illinois median filing of 3,403 and 32 times the national median of 4,000 across all 7,884 filings. It is one of 801 filings of 100,000 or more individuals.
As of 28 August 2026 the case is listed in the HHS OCR breach portal archive. OCR's closing summary of the case is reproduced in full below.
Illinois's breach notification statute (815 ILCS 530) requires notice to affected residents in the most expedient time possible and without unreasonable delay. Its attorney general threshold: more than 500 Illinois residents (private collectors); 250 for state agencies. The HIPAA Breach Notification Rule ran alongside it: notice to affected individuals and to HHS without unreasonable delay and no later than 60 days after discovery, which is the clock that put this filing on the portal.
Multiplying 129,682 individuals by IBM's $160 customer-PII cost per record (Cost of a Data Breach 2025, the figure the site's calculator uses) gives a modelled $20.7M; the 2026 edition's $192 gives $24.9M. Both are modelled estimates with the method shown, not costs disclosed by Aon PLC. Because the filing is above the roughly 100,000-record range in which the per-record figure is reliable, the result is an upper bound, not an estimate: fixed costs are spread across far more records at this scale.
Section F.3 / OCR closing summary
The portal's archived description, in full
Written by the Office for Civil Rights when the case was closed and reproduced verbatim from the HHS export.
Aon, a business associate (BA) and covered entity (CE), reported that it experienced a ransomware incident that affected the protected health information (PHI) of 129,682 individuals. The PHI involved included names, dates of birth, Social Security numbers, drivers' license numbers, health insurance information, and other treatment information. The BA/CE notified HHS, affected individuals, and the media. In response to the breach, the BA/CE offered complimentary credit monitoring and identity theft protection services and implemented additional administrative and technical safeguards. Staff were also retrained on protecting and securing PHI.
Section F.5 / Modelled cost
129,682 individuals through IBM's per-record figures
Modelled cost / method shown, not a disclosed cost
Upper boundIBM 2025 customer PII, $160 per record
$20.7M
129,682 x $160
IBM 2026 customer PII, $192 per record
$24.9M
129,682 x $192
Method: individuals affected, as reported by Aon PLC to HHS, multiplied by IBM's customer-PII cost per record (Cost of a Data Breach 2025 Figure 6 and the 2026 edition). No cost has been disclosed by the entity for this filing; the figure is a planning estimate, not a fact about the breach. IBM's per-record figures come from mid-volume breaches and IBM cautions against applying them to breaches involving millions of records; the site's per-record page explains where the multiplication holds and where it breaks down.
Context: IBM's average cost of a healthcare breach is $6.64M in the 2026 report ($7.42M in 2025); the global average across all sectors was $4.44M in 2025.
Cost per record: method and limits / Healthcare breach cost, IBM 2026
Section F.6 / Notification clock
Illinois statute and the HIPAA rule
State notification statute
Illinois: 815 ILCS 530
Personal Information Protection Act (PIPA)
- Notice to individuals
- In the most expedient time possible and without unreasonable delay
- Attorney general threshold
- More than 500 Illinois residents (private collectors); 250 for state agencies (Within 45 days of discovery or at the time of consumer notice, whichever is sooner)
- Private right of action
- No: No direct PROA under PIPA; claims may run through the Consumer Fraud Act, and BIPA covers biometric data separately
- Penalty
- Up to $50,000 per violation under the Consumer Fraud Act; restitution prioritized over penalties
The HIPAA Breach Notification Rule runs alongside the state statute: notice to affected individuals and to HHS without unreasonable delay and no later than 60 days after discovery.
Section F.7 / Peer filings
Illinois filings closest in size
Neighbours by size rank among Illinois filings in 2022, topped up from other years where 2022 has too few. Filings of 10,000 or more link to their own page.
| Covered entity | Type | Individuals | Submitted | Breach type | Location | BA |
|---|---|---|---|---|---|---|
| Lutheran Social Services of Illinois | Healthcare Provider | 146,028 | 25 Mar 2022 | |||
| Michigan Avenue Immediate Care | Healthcare Provider | 144,104 | 30 Jun 2022 | |||
| South Shore Hospital Corporation | Healthcare Provider | 115,175 | 7 Feb 2022 | |||
| Finkelstein Eye Associates | Healthcare Provider | 48,587 | 27 May 2022 |
Index / Companion schedules
13 HHS breach register
→Hub: every filing, by state, year and entity.
04 Biggest breaches
→Mega-breaches with primary-source cost figures.
Industry / Healthcare
→IBM 2026: $6.64M average, 13 years at #1.
Regulation / HIPAA penalties
→OCR enforcement tiers and the 60-day rule.
11 50-state laws
→Deadline, AG threshold and penalties per state.
Cost / Per record
→Where the per-record model is reliable.
Provenance
Source: U.S. Department of Health and Human Services, Office for Civil Rights, Breach Portal (breaches affecting 500 or more individuals), retrieved 2026-08-28. Public domain. Individuals affected and dates as reported by the covered entity.
Portal: ocrportal.hhs.gov breach report. Statutory basis: HITECH Act section 13402(e)(4): the Secretary must post a list of breaches of unsecured protected health information affecting 500 or more individuals. Breaches affecting fewer than 500 individuals are reported to OCR annually and are not posted, so they are not on this register. Status wording follows the portal's two tabs ("Cases Currently Under Investigation" and "Archive") as of 28 August 2026; a filing moves to the archive when OCR closes the case. Modelled costs on this site are a method applied to the reported count, using IBM Cost of a Data Breach per-record figures, and are never a cost disclosed by the entity. This row: hhs-breach-archive__2026-08-28.csv, export row 2476.
Corrections: if you represent a listed entity and the portal row has been amended, email [email protected] with the portal entry and we will re-pull the export.