Customers of UK ticketing agency TicketWeb, a subsidiary of TicketMaster, received phishing emails from the company over the weekend after its direct email marketing system was hacked.
Users received an email that told them their current version of Adobe Acrobat Reader was out of date, and asked them to upgrade to the 2012 version. Within the email was a link to the upgrade that took them to a third-party website where they were asked for personal information, including their card details.
"On Saturday February 11, some of our customers received up to four unauthorised emails," a TicketWeb spokesperson told The Register.
"These emails contained a link that customers may have followed and subsequently entered information into a third party website.
"Customers who may have entered card details upon following the link have been advised to contact their card issuer immediately for advice in respect of the best course of action to take in their particular circumstances."
After the spam mails were sent out, TicketWeb emailed its customers with an urgent message warning them about the security breach and advising them that the emails were unauthorised.
The ticketing firm said that it had "taken immediate action to close the vulnerability".
"No sensitive personal information or credit card information was vulnerable directly from the TicketWeb UK direct email marketing system during this incident," the spokesperson said.
"We sincerely regret any concern that may have been caused. TicketWeb UK takes the security of customer data very seriously and will be liaising with the Information Commissioner’s Office in relation to this unauthorised system access."
The firm said it couldn't provide any more information at this stage about what sort of vulnerability had been exploited.
TicketWeb sells tickets to all sorts of events in the UK, including gigs, theatre performances, comedy clubs, festivals and nightclubs. ®