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Semple, Marchal & Cooper, LLP

listed as Semple & Cooper · Claimed by Interlock · listed 1 year ago

14m
Age
since listed · data leaked

Status timeline

  1. ListedMay 21, 2025
  2. Data leakeddate unknown

At a glance

Group
Interlock
Status
Data leaked
Country
United Kingdom
Listed on leak site
May 21, 2025

About the victim

AI dossier — public-source company profile

Semple, Marchal & Cooper, LLP is a regional Certified Public Accounting firm offering accounting, auditing, tax planning, compliance, and management consulting services. The firm serves clients across technology, healthcare, retail, and non-profit sectors.

Industry
Accounting & Professional Services

Attack summary

Severity: high — CPA firm holds regulated financial and tax data for multiple clients across sensitive sectors (healthcare, non-profits). Breach of accounting firm creates exposure to PII, financial records, and proprietary business information at scale, even without specific proof inventory listed.

Interlock claims to have breached Semple, Marchal & Cooper, LLP and published data. The specific nature of exfiltration (encryption, data theft, or both) and data categories are not detailed in the available post excerpt.

high

Data the group says was taken

AI dossier — extracted from the leak post
  • client financial records
  • tax documentation
  • audit materials
  • business correspondence

What the group claims

Semple, Marchal & Cooper, LLP is a leading regional Certified Public Accounting firm based in the Southwest, offering a range of professional services including accounting, auditing, tax planning, compliance, and management consulting. The firm is dedicated to serving various sectors such as technology, healthcare, retail, and non-profits, emphasizing innovation and personalized solutions for each client.

Sources

Source

Indexed 1 year 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 Interlock

Interlock is a recently emerged ransomware group that began operations in October 2024, primarily motivated by financial gain through extortion activities targeting organizations across multiple sectors. The group's country of origin and potential affiliations remain unclear given their recent emergence, with insufficient public documentation to determine whether they operate as an independent entity or under a Ransomware-as-a-Service model. Limited public information exists regarding their specific attack methodologies, initial access vectors, or encryption techniques, as major cybersecurity firms and law enforcement agencies have not yet published comprehensive technical analyses of their operations. Since beginning operations, Interlock has reportedly compromised approximately 100 victims, with their targeting primarily focused on organizations in English-speaking countries including the United States, Canada, United Kingdom, and Australia, as well as Italy, while demonstrating a preference for attacking education, manufacturing, healthcare, and public sector entities. The group remains active as of late 2024, though comprehensive threat intelligence profiles from established security research organizations have not yet been published due to the group's recent emergence in the threat landscape. The group has been linked to 114 public disclosures across our corpus. First observed on a leak site on October 13, 2024; most recent post July 10, 2026. The operation is currently active.

Timeline of this disclosure

  • May 21, 2025Semple & Cooper listed by Interlockon the group's public leak site

Other recent disclosures by Interlock

Interlock has been linked to 114 public victims on Darkfield. A sample of the most recent:

See the full Interlock dossier →

Sector and geography

Geographically, Semple & Cooper is reported in United Kingdom, a country with 1,217 ransomware disclosures in our corpus.

If your organisation is affected

A listing by Interlock means Semple & Cooper 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, NCSC (United Kingdom), as required for your jurisdiction.
  • Monitor for the data appearing on Interlock'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.