Excerpt: For the second time in a month, a payment processor has reported being hit by data thieves.

This time, the victim is Heartland Payment Systems, one of the five largest payment processors in the United States. Heartland (NYSE: HYP) has not disclosed how many people were affected by the security breach, which it said may have begun in 2008 and was only uncovered last week.

According to Heartland, the scope of the data loss is still being assessed. Credit card account numbers, expiration dates and, in some cases, cardholders' names, were stolen in the attack, Nancy Gross, a Heartland spokesperson, told InternetNews.com. However, the company does not yet know how many cardholders or businesses were impacted. The 12 -year-old payment processor serves 250,000 business locations and more than four billion transactions every year, according to its Web site.

"The investigation is still ongoing and we have very far from complete information," Gross said. ...