Was NTT Docomo - Japan 1st Mobile Operator hit by ransomware?

NTT Docomo - Japan 1st Mobile Operator was listed by the ransomed ransomware operation (Japan), and stolen data was published on the group's leak site. Darkfield tracks this disclosure with the original leak post, screenshot and group context.

Who is the ransomed ransomware group?

ransomed is a ransomware operator tracked by Darkfield. See the full operator dossier for its known victims, sectors targeted, IOCs and leak-site infrastructure.

What data was leaked in the NTT Docomo - Japan 1st Mobile Operator breach?

ransomed published data attributed to NTT Docomo - Japan 1st Mobile Operator, around 310.000 employees records. Darkfield captured the leak post and a screenshot of the listing.

Ransomware victim disclosure

← All victims

NTT Docomo

listed as NTT Docomo - Japan 1st Mobile Operator · Claimed by Ransomed · listed 3 years ago

310.000 employees

Records

$1.015

Ransom

demanded

34m

Age

since listed · data leaked

Status timeline

ListedSep 26, 2023
Data leakeddate unknown

At a glance

Group: Ransomed
Status: Data leaked
Country: Japan
Sector: Telecommunications
Listed on leak site: Sep 26, 2023
Records: 310.000 employees
Ransom demanded: $1.015

About the victim

AI dossier — public-source company profile

NTT Docomo is Japan's largest mobile network operator and a subsidiary of NTT (Nippon Telegraph and Telephone Corporation), one of the world's leading telecommunications carriers with approximately 310,000 employees worldwide. The company offers a wide range of services including mobile phones, fixed-line telephony, internet access, and system integration. NTT is reported to serve 88% of the Fortune 500's top 100 companies globally.

Industry: Telecommunications – Mobile Network Operator
Employees: 310000

Attack summary

Severity: high — The group claims broad exfiltration from a major telecommunications carrier serving hundreds of millions of customers and critical enterprise clients; however, no specific data categories, proof files, or confirmed data size are provided, limiting the classification to high rather than critical.

The group 'ransomed' claims to have gained access to NTT Docomo's infrastructure and exfiltrated data, stating they 'exfiltrated everything' after not receiving payment. A ransom demand of $1,015,000 is stated in the post.

high

Data the group says was taken

AI dossier — extracted from the leak post

Exfiltrated internal data (unspecified)

What the group claims

With approximately 310,000 employees worldwide, NTT (Nippon Telegraph and Telephone Corporation) is one of the world's leading telecommunications carriers. It is chosen by as many as 88% of the top 100 companies in the Fortune Global Business Ranking "Fortune 500", an annual U.S. business magazine. We offer a wide range of services in Japan, from fixed-line and mobile phones to the Internet and system integration.We have got into their base and exfiltrated everything from there, we dont get paid.We require a ransom of $1,015,000

Sources

Victim sitenttdocomo.co.jp

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.

Is this your supplier? Your competitor? You?

Pro plans monitor your domain, corporate emails, and crypto wallets across every new ransomware leak-site post, breach dump and Telegram callout — alerts within 5 minutes.

Disclosure context

About ransomed

The ransomed ransomware group is a relatively new cybercriminal organization that emerged in August 2023, primarily motivated by financial gain through extortion activities targeting organizations across multiple countries. Based on their targeting patterns across Japan, Brazil, Russia, Great Britain, and Bulgaria, the group appears to operate internationally without clear geographic limitations, though their country of origin and potential affiliations with other ransomware groups remain undetermined due to limited public intelligence reporting. Given the recent emergence of this group and lack of detailed technical analysis from major security firms, their specific attack methodologies, initial access vectors, and encryption techniques have not been comprehensively documented in publicly available threat intelligence reports from CISA, FBI, or established security researchers. The group has claimed approximately 68 victims across their identified target countries since becoming active, though no specific high-profile campaigns or notable ransom demands have been publicly reported by law enforcement or security organizations. As of current reporting, the group appears to remain active with continued victim claims, though the limited public documentation suggests they operate as a lower-profile ransomware operation compared to more established and widely-tracked ransomware families. The group has been linked to 68 public disclosures across our corpus. First observed on a leak site on August 21, 2023; most recent post October 30, 2023. The operation is currently inactive.

Timeline of this disclosure

September 26, 2023NTT Docomo - Japan 1st Mobile Operator listed by ransomedon the group's public leak site

Records: 310.000 employees
Ransom demanded: $1.015

Other recent disclosures by ransomed

ransomed has been linked to 68 public victims on Darkfield. A sample of the most recent:

See the full ransomed dossier →

Sector and geography

This disclosure adds to ransomware activity in the Telecommunications sector, which has 87 disclosures indexed across all operators we track. Geographically, NTT Docomo - Japan 1st Mobile Operator is reported in Japan, a country with 220 ransomware disclosures in our corpus.

If your organisation is affected

A listing by ransomed means NTT Docomo - Japan 1st Mobile Operator appeared on a ransomware extortion site and data attributed to it has been published. If this is your organisation, or a supplier you depend on, the priority is to confirm the intrusion and contain it before the window to act closes.

Engage your incident-response team and preserve forensic evidence before remediating — do not wipe affected systems first.
Force a password reset and revoke active sessions for exposed accounts; rotate any credentials, API keys or certificates that may have been in the stolen data.
Assess regulatory notification duties (GDPR, NIS2, sector regulators) — many carry a 72-hour reporting clock from awareness.
Report the incident to your national CERT, JPCERT/CC (Japan), as required for your jurisdiction.
Monitor for the data appearing on ransomed's leak site and across paste and breach channels, and brief downstream partners who may be exposed through you.

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.