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, 2025SystemExec Co., Ltd. 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, SystemExec Co., Ltd. is reported in Japan, a country with 108 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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SystemExec Co., Ltd.

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: Japan
Sector: Not Found
Listed on leak site: Aug 26, 2025

About the victim

AI dossier — public-source company profile

SystemExec Co., Ltd. (システムエグゼ) is an independent Japanese IT system integrator and prime vendor headquartered in Chuo-ku, Tokyo. The company provides end-to-end IT services including custom application development, IT infrastructure, cloud, AI, data utilization, DX solutions, and offshore development. It was newly listed on the Tokyo Stock Exchange Standard Market in April 2026.

Industry: IT Services & System Integration
Address: 〒103-0022 東京都中央区日本橋室町3-4-4 OVOL日本橋ビル7階 (OVOL Nihonbashi Bldg. 7F, 3-4-4 Nihonbashi Muromachi, Chuo-ku, Tokyo 103-0022, Japan)

Attack summary

Severity: high — 30+ GB of GitLab repository contents have reportedly been published, exposing proprietary source code and potentially sensitive configuration or credential data from a publicly listed IT system integrator. Exposure of internal codebases and related secrets at this scale constitutes significant confirmed exfiltration of business-critical data.

The ransomware group 'cephalus' claims to have exfiltrated over 30 GB of data from SystemExec's GitLab repositories, described as a 'naked repo leak', indicating source code and potentially associated credentials or configuration data were exposed. The disclosure status is 'data_published', suggesting the data has already been released.

high

Data the group says was taken

AI dossier — extracted from the leak post

GitLab source code repositories
Software project files
Potentially embedded credentials or configuration files
Internal development assets

What the group claims

SystemExec Co., Ltd. (システムエグゼ) GitLab naked repo leak | 30G+

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.