Ransomware attacks in May 2025: 121 confirmed incidents

// CONFIRMED RANSOMWARE ATTACKS · MONTH

Ransomnews has confirmed 121 ransomware attacks in May 2025, each one verified against a public source such as a breach notification, regulatory filing, court record or press report. That is 1.3% of the 9,520 confirmed incidents in the dataset. That compares with 107 in April 2025 and 114 in May 2024. The United States accounts for 75 of them (62%), with victims recorded in 21 countries in total. The most affected sector is healthcare, with 33 confirmed victims (27%). Where the operator is attributed, Qilin leads with 17 confirmed victims. A ransom payment is on the public record in 1 case and a refusal in 13; the outcome is unrecorded in the remaining 107.

Confirmed ransomware attacks by month, trailing 13 months to May 2025

Every month is a partial count until disclosures stop arriving, which typically takes three to four months. Compare May 2025 with months of the same age rather than with fully matured ones.

Which ransomware groups had the most confirmed victims in May 2025

The operator is attributed in 97 of the 121 confirmed incidents. Counts are confirmed victims, not leak-site claims, so they run well below the totals the groups publish about themselves. Group names link to the live Ransomtracker profile where one exists.

Where the confirmed attacks in May 2025 fall

Country shares carry a reporting bias. United States breach-notification law and SEC disclosure rules push far more incidents onto the public record than most jurisdictions, which makes American attacks easier to confirm and inflates the US share of any confirmed dataset.

Ransom payment outcomes in May 2025

Among the 14 confirmed incidents in May 2025 where the outcome is on the public record, 1 paid and 13 refused, a disclosed payment rate of 7.1%. The remaining 107 carry no public statement either way. Victims that pay have every incentive to stay quiet and public bodies are the most likely to announce a refusal, so treat this as the disclosed rate, not the true one. The ransomware payment rate analysis explains how the disclosed rate has moved since 2018 and how it compares with incident-response firm samples.

Largest confirmed ransomware attacks in May 2025 by records exposed

Record counts are recorded only where a named source disclosed them, which is the minority of cases, so this table ranks disclosed impact rather than true impact.

All confirmed ransomware attacks in May 2025

All 121 of 121 confirmed incidents. Every row links to the public source it was verified against.

Frequently asked questions

How to read this page. Every incident counted here was verified by Ransomnews against at least one public source. Leak-site listings alone do not qualify, because operators inflate, duplicate and occasionally fabricate claims, so these totals are a defensible floor rather than a full census. Records exposed and ransom outcomes appear only where a named source disclosed them. The page is regenerated from the live database, which refreshes weekly. Cite as: Ransomnews Confirmed Ransomware Attacks Dataset, ransomnews.com, with a link to this page. Bulk access and methodology questions: [email protected]. See also the monthly ransomware statistics and the Ransomtracker.