Personal details of customers of large US companies including Citigroup and Walgreen are feared to have been compromised in a massive and growing data breach of online marketer Epsilon.
The breach, which security experts have termed as one of the biggest in US history, may have exposed the names and e-mail addresses of College Board students as well.
Alliance Data Systems subbsidiary Epsilon has said that on 30 March, "A subset of Epsilon clients’ customer data [was] exposed by an unauthorized entry into Epsilon’s email system."
However, the company said that financial information was safe.
It said, "The information that was obtained was limited to email addresses and/or customer names only," adding that "no other information associated with those names was at risk."
Fears of "phishing" or phony e-mails are pushing affected companies to warn their customersof a possible leak of information.
Citigroup has started warning its customers of the breach through its website. The College Board has warned students against divulging personal information solicited by e-mails. Walgreen and Kroger have also issued similar warnings.
Verizon Communications, Blackstone Group LP’s Hilton Hotels, Kraft Foods and AstraZeneca are some of Epsilon’s other clients.
The company has said that an investigation on the breach is on.
