Was North Star Asset Management hit by ransomware?

North Star Asset Management was listed by the sinobi ransomware operation (United States), 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 sinobi ransomware group?

sinobi 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 North Star Asset Management breach?

sinobi published data attributed to North Star Asset Management. Darkfield captured the leak post and a screenshot of the listing.

Ransomware victim disclosure

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North Star Asset Management

Claimed by Sinobi · listed 7 months ago

$3B

Ransom

demanded

Age

since listed · data leaked

Status timeline

ListedDec 19, 2025
Data leakeddate unknown

At a glance

Group: Sinobi
Status: Data leaked
Country: United States
Sector: Financial Services
Listed on leak site: Dec 19, 2025
Ransom demanded: $3B

About the victim

AI dossier — public-source company profile

North Star Asset Management, Inc. is an independent SEC Registered Investment Advisory firm headquartered in Wisconsin, managing nearly $3 billion in client assets. The firm provides tailored investment management and retirement planning services for families, corporations, and endowments, operating under a fiduciary standard. Its team comprises 11 investment professionals, including 9 CFA Charterholders and 2 CFP professionals, with over 200 years of combined experience.

Industry: Registered Investment Advisory & Wealth Management
Address: Wisconsin, United States
Employees: 11

Attack summary

Severity: critical — The victim is an SEC-registered investment advisor managing ~$3B in assets for families, corporations, and endowments. Data published by the threat actor almost certainly includes regulated financial data and PII of high-net-worth individuals and institutional clients, constituting confirmed exfiltration of sensitive financial and personally identifiable data at scale.

The group sinobi claims to have compromised North Star Asset Management and has published data (disclosed status: data_published), with a stated ransom demand of $3 billion. The specific nature of the data exfiltrated or encrypted is not detailed in the post, but the firm's client financial records, PII, and investment portfolios are at significant risk given the nature of the business.

critical

Data the group says was taken

AI dossier — extracted from the leak post

Client financial records
Investment portfolio data
Personally identifiable information (PII)
Retirement planning documents
Corporate and endowment client records
Internal investment professional credentials/data

What the group claims

North Star Asset Management, Inc. is a prominent independent SEC Registered Investment Advisory firm based in Wisconsin, managing nearly $3 billion in assets. They offer tailored investment management and retirement planning services for families, corporations, and endowments, always prioritizing client interests as fiduciaries. Their team consists of 11 investment professionals, including 9 CFA Charterholders and 2 CFP professionals, boasting over 200 years of combined investment experience. North Star is recognized for its personalized and independent financial advice, charging a fee of 0.6% of managed assets.

Sources

Leak posthttp://sinobi6ftrg27d6g4sjdt65malds6cfptlnjyw52rskakqjda6uvb7yd.onion/leaks/6945c6cc88b6823fa2d6938f

Source

Indexed 7 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.

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Disclosure context

About sinobi

Based on the limited publicly available information, Sinobi appears to be a recently emerged ransomware operation first observed in July 2025, with financial motivations evidenced by their targeting of 268 victims across multiple sectors. The group's origin and specific affiliations remain undocumented in public threat intelligence reporting, and there is no confirmed information regarding whether they operate as a Ransomware-as-a-Service model or as an independent entity. Their attack methodology and technical capabilities have not been extensively documented by major security research organizations, though their targeting patterns suggest a broad opportunistic approach rather than highly selective operations. The group demonstrates a preference for targeting organizations in the United States, India, United Kingdom, Canada, and Italy, with a focus on manufacturing, healthcare, construction, and technology sectors, suggesting they may exploit common vulnerabilities across these industries rather than deploying sophisticated, sector-specific attack vectors. No major high-profile campaigns or significant law enforcement actions against Sinobi have been publicly reported by CISA, FBI, or established threat intelligence firms. Given the recent emergence timeline and lack of extensive public documentation, the group's current operational status and long-term trajectory remain unclear, though the substantial victim count suggests continued activity as of the last available reporting period. The group has been linked to 274 public disclosures across our corpus. First observed on a leak site on July 5, 2025; most recent post May 8, 2026. The operation is currently active.

Timeline of this disclosure

December 19, 2025North Star Asset Management listed by sinobion the group's public leak site

Ransom demanded: $3B

Other recent disclosures by sinobi

sinobi has been linked to 274 public victims on Darkfield. A sample of the most recent:

See the full sinobi dossier →

Sector and geography

This disclosure adds to ransomware activity in the Financial Services sector, which has 1,184 disclosures indexed across all operators we track. Geographically, North Star Asset Management is reported in United States, a country with 11,033 ransomware disclosures in our corpus.

If your organisation is affected

A listing by sinobi means North Star Asset Management 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, CISA (United States), as required for your jurisdiction.
Monitor for the data appearing on sinobi'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.