Disclosure context

About TEAM UNDERGROUND

TEAM UNDERGROUND is a ransomware group first observed in May 2026 with an apparent financial motivation, though its limited operational history makes comprehensive attribution difficult at this time. With only a single known victim recorded to date, the group has demonstrated a targeting preference for the Audit, Tax Advisory, and Legal Services sector, suggesting a deliberate focus on organizations that handle sensitive financial, legal, and confidential client data — a common strategic choice among financially motivated threat actors seeking high-value exfiltration leverage. Given the group's extremely recent emergence and minimal operational footprint, detailed technical indicators regarding their initial access vectors, tooling, encryption methodology, or affiliation with broader ransomware ecosystems have not yet been publicly documented by authoritative sources such as CISA, the FBI, Mandiant, or equivalent research bodies. No confirmed affiliations with known ransomware-as-a-service platforms or established threat actor groups have been publicly established, nor have any notable high-profile campaigns, law enforcement actions, or ransom figures been attributed to this group in open-source reporting. TEAM UNDERGROUND should currently be regarded as an emerging and closely monitored threat, with its full capabilities, infrastructure, and operational scope remaining largely uncharacterized pending further observed activity and independent security research. The group has been linked to 6 public disclosures across our corpus. First observed on a leak site on May 14, 2026; most recent post May 21, 2026. The operation is currently active.

Timeline of this disclosure

May 17, 2026TPA Group (tpa-group.sk) listed by TEAM UNDERGROUNDon the group's public leak site

Ransom demanded: $15 million

How we know this. Darkfield monitors public ransomware leak sites continuously, archiving every new disclosure and the data later released against the victim. Each entry on this page is sourced from the operator's own publication and cross-checked against complementary OSINT feeds (RansomLook, ransomware.live, RansomWatch). We do not collect or host stolen data — only the metadata, timestamps and screenshots needed to make the public disclosure searchable and accountable. Records here are corrected when the original post is edited, retracted, or merged with another disclosure.

Ransomware victim disclosure

← All victims

TPA Slovensko

listed as TPA Group (tpa-group.sk) · Claimed by TEAM UNDERGROUND · listed 4 days ago

$15 million

Ransom

demanded

Age

since listed · listed for ransom

Status timeline

Listed
May 17, 2026

Current state: Listed for ransom

At a glance

Group: TEAM UNDERGROUND
Status: Listed for ransom
Listed on leak site: May 17, 2026
Ransom demanded: $15 million

About the victim

AI dossier — public-source company profile

TPA Slovensko (tpa-group.sk) is the Slovak member firm of TPA Group, an international tax advisory, accounting, and audit network affiliated with Baker Tilly International. The firm provides tax, accounting, and advisory services across multiple sectors in Slovakia. It operates as part of a broader Central and Eastern European professional services group.

Industry: Tax Advisory & Accounting Services

Attack summary

Severity: medium — The post is a listing-only disclosure with a ransom demand but no proof files, no confirmed exfiltration of specific regulated data, and no data volume stated; however, a professional tax and accounting firm would hold sensitive financial and client PII, elevating potential impact above low.

TEAM UNDERGROUND claims an attack on TPA Group entities, listing tpa-group.com with a $281 million ransom demand and tpa-group.sk with a $15 million demand, suggesting exfiltration or encryption across multiple group entities; no specific data type or volume has been disclosed in the post.

medium

The leak post

captured from the group's site

All data | Underground store Data Announcements All data Afghanistan Albania Algeria American Samoa Andorra Angola Anguilla Antigua and Barbuda Argentina Armenia Aruba Australia Austria Azerbaijan Bahamas Bahrain Bangladesh Barbados Belarus Belgium Belize Benin Bermuda Bhutan Bolivia Bonaire, Sint Eustatius and Saba Bosnia and Herzegovina Botswana Brazil British Virgin Islands Brunei Darussalam Bulgaria Burkina Faso Burundi Cambodia Cameroon Canada Cape Verde Cayman Islands Central African Republic Chad Chile China Colombia Comoros Congo Congo, Democratic Republic Cook Islands Costa Rica Côte d`Ivoire Croatia Cuba Curaçao Cyprus Czech Republic Denmark Djibouti Dominica Dominican Republic East Timor Ecuador Egypt El Salvador Equatorial Guinea Eritrea Estonia Ethiopia Falkland Islands Faroe Islands Fiji Finland France French Guiana French Polynesia Gabon Gambia Georgia Germany Ghana Gibraltar Greece Greenland Grenada Guadeloupe Guam Guatemala Guinea Guinea-Bissau Guyana Haiti Honduras Hong Kong Hungary Iceland India Indonesia Iran Iraq Ireland Isle of Man Israel Italy Jamaica Japan Jordan Kazakhstan Kenya Kiribati Kuwait Kyrgyzstan Laos Latvia Lebanon Lesotho Liberia Libya Liechtenst…

Sources

Victim sitetpa-group.sk
Leak posthttp://47glxkuxyayqrvugfumgsblrdagvrah7gttfscgzn56eyss5wg3uvmqd.onion

Source

Indexed 4 days ago

This page surfaces a public ransomware disclosure indexed by Darkfield. Original posts come from the operator's own leak site; we cross-check against ransomware.live, RansomLook and RansomWatch where applicable. Share this URL freely.