Dow Jones & Co. said Friday that hackers have breached its computer systems, looking for contact information to send fraudulent solicitations.

In a letter sent to customers, the financial information company said there is no evidence that data was stolen but that the hackers may also have accessed credit card information of fewer than 3,500 individuals.

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“Out of an abundance of caution, we are notifying you that we recently determined there was unauthorized access to our systems,” CEO William Lewis said in the Sept. 9 letter. “To date, our extensive review has not uncovered any direct evidence that information was stolen, and we have taken steps to stop the unauthorized access.”

The hack appears to have been part of a larger campaign involving “a number of other victim companies,” Lewis said.

“It appears that the focus was to obtain contact information such as names, addresses, email addresses and phone numbers of current and former subscribers in order to send fraudulent solicitations,” Lewis said.

Law enforcement informed Dow Jones of the breach in July. The hackers likely accessed the system “at certain times” from August 2012 up until the company was notified.

Private companies continue to face an onslaught of cyber intrusions, with retailers bearing the brunt of much of the public scrutiny.

Target and Home Depot continue to face fallout from their high-profile breaches.

Earlier this month, T-Mobile revealed that around 15 million of its U.S. customers may have been exposed in a data breach at one of its vendors.

The breach immediately drew the attention of lawmakers. The three leading Democrats on the Senate Commerce Committee wrote the two companies demanding information on how both firms were handling fallout from the hack.

As hacks continue to proliferate, pressure has mounted on lawmakers to pass some form of cybersecurity legislation.

A stalled bill that would boost the flow of threat information between the federal government and private industry is expected to see floor time in the Senate this month.

Dow Jones is working with law enforcement, and the investigation is ongoing.