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Ransomware victim Telecommunication

kisnet.co.jp

Listed by Braincipher on · organisation based in Japan

kisnet.co.jp

Disclosed
May 1, 2026
Leak-site listing date
Threat group
Braincipher
106 victims listed
Country
Japan
#11 most targeted
Sector
Telecommunication

ThreatAI analysis

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

About the Braincipher group

Brain Cipher emerged in July 2024. Both Windows and Linux variants are available. Brain Cipher using the leaked build of LockBit Black for their operations. The group suspected to have exploited CVE-2023-28252 (Microsoft Windows CLFS Driver Privilege Escalation Vulnerability). The Ransom demand ranges from $150,000 to $1,00,0000. Demand to be paid with Monero (XMR) cryptocurrency. In 2025, they have shifted their new Negotiation portal to new server with vanity TOR Domain starting with 'brain'. Braincipher has listed 89 victims since July 2024.

How Braincipher 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 Braincipher across its recorded activity, not a finding about how kisnet.co.jp was reached.

Incident analysis

kisnet.co.jp was listed by Braincipher ransomware, a group with 106 victims recorded in this database. The listing appeared on the group's leak site on May 1, 2026.

kisnet.co.jp is based in Japan and operates in the Telecommunication sector. Japan ranks #11 worldwide for ransomware disclosures, with 301 victims in this database.

Sector context. Organisations in this sector hold valuable data and operational systems that ransomware groups seek to exploit for financial gain through encryption and data exfiltration.

Braincipher 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 kisnet.co.jp attacked by ransomware?

Yes. kisnet.co.jp was listed as a victim of the Braincipher ransomware group on May 1, 2026. The organisation is based in Japan and operates in the Telecommunication sector. The disclosure appeared on the group's dark web leak site.

Which ransomware group attacked kisnet.co.jp?

kisnet.co.jp was attacked by Braincipher ransomware. Braincipher is one of the most active ransomware groups, having claimed 106 victims globally. The group typically employs a double-extortion model: encrypting the victim's files and threatening to publish stolen data.

When did the kisnet.co.jp ransomware attack occur?

The ransomware attack on kisnet.co.jp was disclosed on May 1, 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 kisnet.co.jp ransomware attack?

The specific data stolen from kisnet.co.jp 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 Telecommunication organisation, kisnet.co.jp likely held sensitive business data, client information, and operational records.

How can organisations protect against Braincipher attacks?

To defend against Braincipher 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.