Disclosure context

About cephalus

Based on available public information, Cephalus is a recently emerged ransomware group first observed in August 2025, operating with apparent financial motivations targeting organizations primarily across the United States, United Kingdom, Netherlands, and Ireland. The group has claimed 19 victims since emergence, with no publicly documented country of origin or confirmed affiliations to established ransomware families or RaaS operations by major security researchers or government agencies. Their attack methodology and specific technical capabilities remain largely undocumented in public threat intelligence reporting, though their targeting pattern shows focus on healthcare, business services, financial services, and manufacturing sectors alongside organizations of undetermined industry classification. No major high-profile campaigns, record ransom demands, or law enforcement disruption actions have been publicly reported by CISA, FBI, or established security research firms at this time. The group appears to remain active as of current reporting, though the limited public documentation suggests either highly targeted operations or insufficient analysis coverage by major threat intelligence organizations. The group has been linked to 19 public disclosures across our corpus. First observed on a leak site on August 26, 2025; most recent post August 29, 2025. The operation is currently inactive.

Timeline of this disclosure

August 26, 2025Guerrero Mears LLP listed by cephaluson the group's public leak site

Sector and geography

This disclosure adds to ransomware activity in the Not Found sector, which has 4,859 disclosures indexed across all operators we track. Geographically, Guerrero Mears LLP is reported in United States, a country with 7,392 ransomware disclosures in our corpus.

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

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Guerrero Mears LLP

Claimed by cephalus · listed 9 months ago

Age

since listed · data leaked

Status timeline

Listed
Aug 26, 2025
Data leaked

At a glance

Group: cephalus
Status: Data leaked
Country: United States
Sector: Not Found
Listed on leak site: Aug 26, 2025

About the victim

AI dossier — public-source company profile

Guerrero Mears LLP is a boutique transactional law firm based in Bakersfield, California, serving the Central Valley. The firm specializes in business transactions, real estate, estate planning, and tax matters, representing clients ranging from large multinational companies to small family businesses. The firm has over 10 years of experience and employs five attorneys and four support staff.

Industry: Boutique Transactional Law Firm
Address: 5016 California Avenue, Second Floor, Suite 7, Bakersfield, California 93309
Employees: 1-10

Attack summary

Severity: high — As a law firm, Guerrero Mears LLP likely holds highly sensitive and legally privileged client data including financial records, estate plans, tax documents, and business transaction files for individuals and companies. Confirmed data publication constitutes a significant breach of confidential and potentially regulated information.

The group 'cephalus' claims to have exfiltrated data from Guerrero Mears LLP and has published the data; the size of the exfiltrated data was not recorded. No encryption claim is stated.

high

Data the group says was taken

AI dossier — extracted from the leak post

Client legal files
Business transaction documents
Estate planning documents
Tax records
Real estate transaction records
Potentially privileged attorney-client communications

What the group claims

Guerrero Mears LLP DATALEAK | (FORGOT THE SIZE)

Sources

Victim sitegmllp.com
Leak posthttps://darkforums.st/Thread-Document-Guerrero-Mears-LLP-DATALEAK-FORGOT-THE-SIZE

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.