When news broke of the Eisner Advisory Group LLC data breach, most headlines summarized it as just another incident in a long line of cyberattacks tied to MOVEit. But this one is different. The breach happened in September 2023, yet affected clients weren’t notified until April 2025. That’s over 18 months of silence—a delay that demands scrutiny.
This blog breaks down the timeline, the attack method, the real-world impact on victims, and the serious lessons for businesses handling sensitive data today.
Who Is Eisner Advisory Group LLC?
Eisner Advisory Group LLC is a division of EisnerAmper LLP, one of the leading accounting and advisory firms in the United States. Headquartered in New York, the firm provides a wide range of professional services, including:
- Tax advisory and compliance
- Audit and assurance
- Wealth management
- Risk and regulatory consulting
- Business consulting for private enterprises, high-net-worth individuals, and institutional clients
EisnerAmper operates across sectors such as finance, healthcare, real estate, technology, and private equity. Given the firm’s extensive involvement with sensitive financial and personal data, it maintains — or is expected to maintain — rigorous data governance practices.
That’s exactly why the Eisner Advisory Group LLC Data Breach has raised significant concern. The breach impacted not just internal data systems, but also the trust placed in one of the nation’s most respected financial advisory entities.
Timeline of the Eisner Advisory Group Data Breach
- September 4–9, 2023: Attackers exploited a vulnerability in the MOVEit file transfer tool used by Eisner Advisory Group LLC.
- Following Months: An internal forensic investigation began, likely involving third-party cybersecurity firms and legal advisors.
- April 2025: Official data breach letters were sent out to impacted individuals, citing sensitive data exposure.
The long gap between breach and disclosure appears to stem from prolonged forensic analysis, determining the extent of compromised data, notifying regulators, and possibly awaiting legal review for compliance with breach notification laws.
What Happened in the Eisner Advisory Group LLC Data Breach?
In September 2023, Eisner Advisory Group LLC—a major U.S.-based accounting and consulting firm—detected suspicious activity in its systems. The company launched a forensic investigation, and what they found was serious. Between September 4 and 9, attackers accessed files containing personal data.
Here’s the part that caught attention: clients weren’t notified until April 2025.
That delay triggered legal scrutiny and raised questions about how long the data had been exposed. As of now, the firm has acknowledged that names, Social Security numbers, driver’s license and passport details, financial records, and even health insurance information may have been accessed.
While the firm did act—by shutting down the affected systems, hiring forensic experts, and notifying authorities—the delay in notification left clients exposed for nearly 19 months.
How Did the Breach Happen? Technical Insights Into MOVEit Exploit
The entry point was MOVEit, a widely used secure file transfer tool. In this case, attackers exploited a zero-day vulnerability—a previously unknown flaw that allowed them to bypass authentication and access sensitive files. This type of vulnerability is especially dangerous because traditional security tools often don’t catch it until it’s too late.
If your business uses third-party software like MOVEit, you’re not immune—even if your systems are patched and secure. One weak link in your vendor chain is all it takes.
Who Was Affected?
Eisner Advisory Group LLC provides services to businesses, high-net-worth individuals, and family offices. The breach affected thousands of records, including clients from its tax, estate planning, and business advisory units.
If you’ve worked with any Eisner Advisory Group LLC locations in recent years, particularly their flagship office at Eisner Advisory Group LLC / New York, your information may be at risk.
What Data Was Exposed—and What That Means for Victims?
Eisner Advisory Group’s notice confirms exposure of:
- Full names
- Social Security Numbers (SSNs)
- Financial account info
- Dates of birth
- Medical data (for some)
The issue isn’t just data exposure. Victims could now face:
- Identity theft using SSNs
- Financial fraud via bank details
- Insurance fraud with stolen health data
- Targeted phishing attempts using real names and personal context
For victims, the breach isn’t just an inconvenience—it’s a long-term risk.
Why the Delay in Notification?
That’s the question a lot of people are asking.
The breach was detected in September 2023, yet affected individuals weren’t notified until April 8, 2025. There’s no clear answer from the company, but legal experts are pointing to the possibility of prolonged investigations, internal approvals, and delayed regulatory triggers.
Regardless of reason, this gap created more risk. Hackers often sell or trade stolen information within weeks. By the time clients knew, their data could have been circulated across multiple networks.
Legal and Financial Fallout
Several class-action lawsuits have already been filed against Eisner Advisory Group LLC. These cases allege:
- Negligence in cybersecurity protocols
- Failure to notify victims promptly
- Inadequate third-party risk oversight
While the cases are ongoing, affected individuals may be eligible for compensation, including:
- Reimbursement for losses due to fraud
- Coverage for credit monitoring services
- Damages for emotional distress or inconvenience
Timelines vary, but legal resolution may take years. For now, documentation is key—keep all breach-related communication and track any fraudulent activity.
Which Laws Apply and What Could Happen?
Depending on the nature of each client relationship, several compliance frameworks may come into play:
| Framework | Applies If… | Potential Penalties |
|---|---|---|
| HIPAA | Medical or health data was processed | Up to $1.5 million/year |
| GLBA | Financial information was shared under client advisory | Regulatory fines, client loss |
| CCPA/GDPR | Personal data of California or EU residents was involved | Civil litigation, class-action lawsuits |
Failure to notify promptly could itself trigger additional fines or lawsuits. This isn’t just a technical issue—it’s a legal one.
We’re tracking updates, lawsuits, and user experiences around this breach. Join our Reddit community to share, learn, or ask questions from cybersecurity experts and other affected individuals.
What To Do If You’re a Client?
- Enroll in the credit monitoring services provided.
- Place a fraud alert with a major credit bureau (Experian, Equifax, or TransUnion).
- Monitor financial statements and insurance activity closely.
- Get an IRS Identity Protection PIN to prevent tax return fraud.
- Contact Eisner Advisory Group LLC through the official Eisner Advisory Group LLC phone number if you haven’t received a letter but suspect exposure.
What to Do If You’re a Victim?
- Activate credit monitoring if offered.
- Freeze your credit reports to prevent new account openings.
- Enable fraud alerts with your bank and credit card companies.
- Watch out for phishing emails referencing Eisner, MOVEit, or “security updates.”
If you’ve already experienced misuse of your information, consult a data breach attorney about joining ongoing legal action.
Why Would Eisner Advisory Group Have My Information?
Many clients are asking: Why did they even have my data in the first place?
As a financial consulting and accounting firm, Eisner Advisory Group LLC works with tax clients, estate planning, corporate finance, and M&A advisory. If you’ve worked with them, their partners, or their third-party service providers, your data could have been collected during onboarding, tax filings, or financial consultations.
How to Know if the Data Breach Letter Is Real?
Here’s how to verify whether a breach notice from Eisner Advisory Group is legitimate:
- Check the sender’s domain. Official notices usually come from @eisneramper.com or their legal representatives.
- Cross-reference dates and descriptions with publicly available breach disclosures.
- Look for a clear reference to the MOVEit incident, along with identity monitoring instructions.
- If in doubt, call the official Eisner Advisory Group phone number listed on their verified website.
Lessons for Businesses: What to Do Differently
Let’s be honest — no company wants to be the next Eisner. But if you operate in finance, legal, healthcare, or advisory services, you’re already a target.
Here’s a short checklist every business should adopt immediately:
1. Audit Your Vendors
- Review contracts for breach response timelines
- Check if they undergo regular penetration testing
- Ask if they use zero-day threat monitoring
2. Implement Zero Trust Security
- No implicit trust — even inside the network
- Use identity-based access and multi-factor authentication
3. Build an Incident Response Plan
- Who does what if something happens?
- Test it quarterly
- Include third-party vendor breaches in the scope
If you’re a consultant, MSP, or service provider looking to offer secure, branded VPN solutions to clients — let’s connect. Our team shares regular updates and insights on B2B data protection on Linkedin.
How PureVPN White Label Can Help Businesses Respond Better?
A common thread in modern breaches? Weak access control.
PureVPN’s White Label VPN solution gives businesses full control over remote access. You can limit entry by device, IP, and location. Admin panels let you see which users are accessing which systems and from where.
This kind of visibility helps:
- Detect abnormal logins
- Prevent credential abuse
- Keep sensitive data behind secure layers
If Eisner had implemented stricter access layers via VPN-only gateways, the breach might have stopped at the edge.
That’s what PureVPN White Label helps deliver—secure, scalable, brandable access management built for modern businesses.