(NapaValleyRegister) - As many as 250,000 customers who used their credit cards at dozens of Napa Valley wineries this April had their financial information and personal data stolen by a cyber-thief. However, according to one attorney, no evidence of significant fraudulent use of the data has been found yet.

The intruder gained access to customer names, credit/debit card numbers, related billing addresses and any dates of birth from winery clients using eCellar Systems created by Missing Link Networks of Calistoga.

“Responding to this criminal act is our top priority,” said Paul Thienes, founder and CEO of Missing Link Networks, Inc.

Approximately 70 wineries throughout the Northern California wine region use eCellar to manage their inventory and purchases, in tasting rooms, with wine clubs and online. A complete list of those clients was not provided.

The thief did not have access to any driver’s license numbers, Social Security numbers, CVV verification numbers, or PIN numbers, Thienes wrote.

“We have identified and secured the method that was used to breach our platform,” he said. From now on, no payment card information will be stored by Missing Link.

The credit cards potentially impacted by this event appear to be those swiped or entered manually at the winery, entered online for purchases from winery websites and those retained for wine club shipments.

Credit and debit cards from all four major brands – Visa, MasterCard, American Express, and Discover – were affected. Each of these card companies has been notified of the breach and provided with information for the cards affected.

In addition to offering fraud and identity theft counseling to affected clients, Missing Link Networks also notified the U.S. Secret Service about the theft.

“The Secret Service Electronic Crimes Task Force is currently investigating a network intrusion involving Missing Link Networks,” said Charles Marino, acting special agent in charge of the Secret Service San Francisco field office.

That task force is charged with protecting financial payments systems and investigating suspected cyber breaches.

“The investigation began immediately following initial notification from the company to our office. Missing Link Networks has been extremely cooperative during this investigation and further comment [will not be] not provided due to the ongoing cyber investigation,” he said. Marino could not provide any further details.

According to the state Department of Justice, California customers of the following wineries were affected by the data breach:

— Summers Estate Wines,

— Spring Mountain Vineyard,

— Silverado Vineyards

— Signorello Estate

— Round Pond Estates

— Rhys Vineyards

— Repris Vineyards

— Pride Mountain Vineyards

— Palmaz Vineyards

— Outpost Vineyards

— Martinelli Winery

— Larkmead Vineyards Vintner and Grower

— Jessup Cellars (The Good Life Wine Collective)

— Heitz Wine Cellars

— Gemstone Vineyards

— Flora Springs Winery & Vineyards

— Charles Krug Winery (C. Mondavi & Family)

— Corison Winery

— Cain Vineyard and Winery

— Peter Michael Winery

— Rombauer Vineyards, Inc.,

— Turley Wine Cellars

— Clif Bar Family Winery & Farm.

Wineries with customers in other states are required to notify those customers as well.

Representatives from a number of wineries that were contacted about the cyber-theft either declined to comment or did not return phone calls about the breach. Thienes could not be immediately reached for comment.

Robert Cattanach of the Dorsey Law Firm in Minneapolis primarily works in the areas of data privacy, cyber security and breach response. He is representing a number of the wineries affected by the breach.

Cattanach declined to name them or say how many of the 70 Missing Link Networks clients he represents but that those wineries probably account for 100,000 of the 250,000 people affected.