Disclosure context

About Blackbyte

BlackByte is a ransomware-as-a-service (RaaS) operation that emerged in October 2021, primarily motivated by financial gain through double extortion tactics targeting organizations across multiple sectors. The group is suspected to operate from Russia or former Soviet states based on their use of Russian-language forums and avoidance of targeting organizations in Commonwealth of Independent States countries, though they maintain no confirmed links to other established ransomware families. BlackByte operators typically gain initial access through vulnerable Microsoft Exchange servers, phishing campaigns, and exploitation of remote desktop protocol (RDP) services, employing tools such as Cobalt Strike for lateral movement and data exfiltration before deploying their custom ransomware payload that uses AES-256 encryption with RSA-2048 key protection. The group has demonstrated particular focus on critical infrastructure sectors, with the FBI and CISA issuing joint advisories in February 2022 highlighting attacks against organizations in government, healthcare, manufacturing, and education sectors, including notable incidents affecting San Francisco's transportation authority and multiple healthcare systems across the United States. BlackByte remains active as of 2024, continuing to evolve their tactics and maintain their leak site for publishing stolen data from victims who refuse to pay ransoms. The group has been linked to 147 public disclosures across our corpus. First observed on a leak site on October 4, 2021; most recent post July 30, 2025. The operation is currently inactive.

Timeline of this disclosure

August 24, 2023Ontellus listed by Blackbyteon the group's public leak site

Sector and geography

This disclosure adds to ransomware activity in the Business Services sector, which has 2,640 disclosures indexed across all operators we track. Geographically, Ontellus 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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Ontellus

Claimed by Blackbyte · listed 3 years ago

33m

Age

since listed · data leaked

Status timeline

Listed
Aug 24, 2023
Data leaked

At a glance

Group: Blackbyte
Status: Data leaked
Country: United States
Sector: Business Services
Listed on leak site: Aug 24, 2023

About the victim

AI dossier — public-source company profile

Ontellus, founded in 1975 and rebranded in 2017, is a Houston, Texas-based company providing internet-based medical and legal records retrieval, billing summaries, and related services. The company serves insurance carriers, law firms, and custodians across workers' compensation, medical malpractice, general liability, and mass tort sectors. It operates a HIPAA-compliant portal and offers tools such as record chronology, indexing, social media investigation, and DICOM viewing.

Industry: Legal & Insurance Records Retrieval Services
Address: Houston, Texas, United States
Founded: 1975

Attack summary

Severity: critical — Ontellus handles large volumes of medical records, legal records, and insurance claims data on behalf of insurers and law firms, constituting regulated sensitive data (HIPAA-covered medical records, PII at scale). The disclosed status is 'data_published', confirming actual exfiltration and release of this highly sensitive material.

BlackByte claims to have attacked Ontellus and has published data as indicated by the 'data_published' disclosure status. The attack likely involved exfiltration of business and potentially regulated records given the nature of the company's operations in medical and legal records retrieval.

critical

Data the group says was taken

AI dossier — extracted from the leak post

Medical records
Legal case records
Billing records and summaries
Client insurance claims data
Worker compensation records
Personally identifiable information (PII)
Business operations data

What the group claims

Established in 1975, and rebranded in 2017 Ontellus provides internet-based record retrieving and billing services. Their headquarters are located in Houston, Texas

Sources

Victim siteontellus.com

Source

Indexed 3 years 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.