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Chek Tan and Company, LLP

Claimed by Radar · listed 9 months ago

9m
Age
since listed · data leaked

Status timeline

  1. ListedOct 8, 2025
  2. Data leakeddate unknown

At a glance

Group
Radar
Status
Data leaked
Country
United States
Listed on leak site
Oct 8, 2025

About the victim

AI dossier — public-source company profile

Chek Tan and Company, LLP is an accounting and advisory firm based in San Francisco, California. The firm provides services including accounting, audits, management consulting, IRS representation, and tax management. It operates as a limited liability partnership serving clients in the United States.

Industry
Accounting & Tax Advisory Services
Address
San Francisco, California, United States

Attack summary

Severity: critical — An accounting and tax advisory firm holds highly sensitive regulated financial and personal data (PII, tax returns, IRS records) for its clients at scale. Data has been published, making this a confirmed exfiltration of regulated/sensitive financial and personal information.

The Radar ransomware group claims an attack on Chek Tan and Company, LLP and has published data (disclosed status: data_published), though the specific volume of exfiltrated data and whether encryption occurred are not detailed in the post.

critical

Data the group says was taken

AI dossier — extracted from the leak post
  • Tax records
  • Audit files
  • Financial statements
  • Client PII
  • IRS correspondence
  • Management consulting documents

What the group claims

Chek Tan and Company offers accounting, audits, management consulting, IRS representation, and tax management services. San Francisco, California, United States.

Screenshot of the leak post

Leak screenshot for Chek Tan and Company, LLP

Sources

Source

Indexed 9 months 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.

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Disclosure context

About radar

Radar is an emerging ransomware group that first appeared in September 2025, operating with apparent financial motivations based on their targeting patterns across multiple sectors and countries. The group's origin and affiliations remain unclear due to limited public documentation from established threat intelligence sources, though their geographic targeting suggests a focus on English-speaking nations and select international markets. Based on available victim data, Radar appears to employ opportunistic targeting methods that have successfully compromised 23 organizations across diverse sectors including construction, financial services, transportation/logistics, and technology, with operations spanning the United States, United Kingdom, Australia, Kuwait, and other regions. The group's attack methodology, encryption techniques, and whether they employ double or triple extortion tactics have not been extensively documented by major threat intelligence firms or law enforcement agencies. No significant high-profile campaigns, major ransoms, or law enforcement disruption actions against Radar have been publicly reported by CISA, FBI, or established security research organizations. Given the group's recent emergence and limited public intelligence reporting, Radar's current operational status and long-term capabilities remain under assessment by the cybersecurity community. The group has been linked to 26 public disclosures across our corpus. First observed on a leak site on September 10, 2025; most recent post May 18, 2026. The operation is currently active.

Timeline of this disclosure

  • October 8, 2025Chek Tan and Company, LLP listed by radaron the group's public leak site

Other recent disclosures by radar

radar has been linked to 26 public victims on Darkfield. A sample of the most recent:

See the full radar dossier →

Sector and geography

Geographically, Chek Tan and Company, LLP is reported in United States, a country with 11,033 ransomware disclosures in our corpus.

If your organisation is affected

A listing by radar means Chek Tan and Company, LLP appeared on a ransomware extortion site and data attributed to it has been published. If this is your organisation, or a supplier you depend on, the priority is to confirm the intrusion and contain it before the window to act closes.

  • Engage your incident-response team and preserve forensic evidence before remediating — do not wipe affected systems first.
  • Force a password reset and revoke active sessions for exposed accounts; rotate any credentials, API keys or certificates that may have been in the stolen data.
  • Assess regulatory notification duties (GDPR, NIS2, sector regulators) — many carry a 72-hour reporting clock from awareness.
  • Report the incident to your national CERT, CISA (United States), as required for your jurisdiction.
  • Monitor for the data appearing on radar's leak site and across paste and breach channels, and brief downstream partners who may be exposed through you.

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.