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Cyber Threat
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Ransomware victim Technology

RÉSO

Listed by Dragonforce on · organisation based in France

www.reso.fr

Disclosed
Oct 7, 2026
Leak-site listing date
Threat group
Dragonforce
648 victims listed
Country
France
#6 most targeted
Sector
Technology

ThreatAI analysis

Compiled from this incident record and the threat intelligence profile for Dragonforce. Figures and technique mappings are quoted from the source data, not inferred.

Dragonforce listed RÉSO on its dark web leak site on 7 October 2026. RÉSO is based in France and operates in the Technology sector.

About the Dragonforce group

DragonForce is a major ransomware-as-a-service operation first observed in August 2023 that launched a formal affiliate program offering 80% revenue share, then rebranded as a "ransomware cartel" in 2025, gaining notoriety for high-profile attacks on UK retailers Marks & Spencer, Co-op, and Harrods. Dragonforce has listed 659 victims since October 2022.

How Dragonforce is documented to operate

User Execution T1204 Execution

An adversary may rely upon specific actions by a user in order to gain execution. Users may be subjected to social engineering to get them to execute malicious code by, for example, opening a malicious document file or link. These user actions will typically be observed as follow-on behavior from forms of Phishing. While User Execution frequently occurs shortly after Initial Access it may occur at other phases of an intrusion, such as when an adversary places a file in a shared directory or on a user's desktop hoping that a user will click on it. This activity may also be seen shortly after Internal Spearphishing.

Mitigations: Network Intrusion Prevention, Restrict Web-Based Content, Limit Software Installation, User Training, Execution Prevention, Behavior Prevention on Endpoint

MITRE ATT&CK reference
File and Directory Discovery T1083 Discovery

Adversaries may enumerate files and directories or may search in specific locations of a host or network share for certain information within a file system. Adversaries may use the information from File and Directory Discovery during automated discovery to shape follow-on behaviors, including whether or not the adversary fully infects the target and/or attempts specific actions. Many command shell utilities can be used to obtain this information. Examples include <codedir</code, <codetree</code, <codels</code, <codefind</code, and <codelocate</code. Custom tools may also be used to gather file and directory information and interact with the Native API.

MITRE ATT&CK reference
Data Encrypted for Impact T1486 Impact

Adversaries may encrypt data on target systems or on large numbers of systems in a network to interrupt availability to system and network resources. They can attempt to render stored data inaccessible by encrypting files or data on local and remote drives and withholding access to a decryption key. This may be done in order to extract monetary compensation from a victim in exchange for decryption or a decryption key (ransomware) or to render data permanently inaccessible in cases where the key is not saved or transmitted.

Mitigations: Data Backup, Behavior Prevention on Endpoint

MITRE ATT&CK reference

MITRE ATT&CK techniques attributed to Dragonforce across its recorded activity, not a finding about how RÉSO was reached.

Vulnerabilities Dragonforce is recorded exploiting

6 of these 6 are in the CISA Known Exploited Vulnerabilities catalog, 6 of them recorded by CISA as used in ransomware campaigns. CVEs attributed to Dragonforce across its reported activity. There is no indication that any of these was involved in the RÉSO incident — the source data does not record an entry point.

Incident analysis

RÉSO was listed by Dragonforce ransomware, a group with 648 victims recorded in this database. The listing appeared on the group's leak site on October 7, 2026.

RÉSO is based in France and operates in the Technology sector. France ranks #6 worldwide for ransomware disclosures, with 563 victims in this database.

Sector context. Technology companies hold intellectual property, customer data, and source code — all highly valuable assets. A successful ransomware attack can also put downstream customers at risk through supply chain exposure.

Dragonforce typically follows a double extortion model: data is exfiltrated from the victim's systems before files are encrypted, so the victim faces two demands at once — pay to restore access, and pay to keep stolen data unpublished. The leak site, where this listing appeared, is the lever for the second demand.

Source. Public leak-site disclosures aggregated via the ransomware.live API. The disclosure date is when the listing was published, which can differ from the date of compromise. This site does not publish or link to stolen data. Last updated .

Frequently asked questions

Was RÉSO attacked by ransomware?

Yes. RÉSO was listed as a victim of the Dragonforce ransomware group on October 7, 2026. The organisation is based in France and operates in the Technology sector. The disclosure appeared on the group's dark web leak site.

Which ransomware group attacked RÉSO?

RÉSO was attacked by Dragonforce ransomware. Dragonforce is one of the most active ransomware groups, having claimed 648 victims globally. The group typically employs a double-extortion model: encrypting the victim's files and threatening to publish stolen data.

When did the RÉSO ransomware attack occur?

The ransomware attack on RÉSO was disclosed on October 7, 2026. This date reflects when the victim was published on the threat group's leak site, which may differ from the actual date of initial compromise.

What data was stolen in the RÉSO ransomware attack?

The specific data stolen from RÉSO has not been independently verified by this platform. Ransomware groups typically exfiltrate data before encrypting systems and use the threat of publication to pressure victims. As a Technology organisation, RÉSO likely held source code, intellectual property, and customer data.

How can organisations protect against Dragonforce attacks?

To defend against Dragonforce and similar threat actors, organisations should: maintain regular offline backups tested for restoration; implement network segmentation to limit lateral movement; deploy multi-factor authentication on all remote access; use endpoint detection and response (EDR) tools; conduct regular phishing and security awareness training; and monitor threat intelligence feeds for indicators of compromise (IOCs) associated with active groups.