Credential Stuffing attack on Chick-fil-A impacted +71K users

American fast-food restaurant chain Chick-fil-A reported that the accounts of over 71K users were compromised as a result of a credential stuffing campaign.

The American fast-food restaurant chain Chick-fil-A notified over 71K users that their accounts have been compromised in a credential stuffing campaign that lasted at least two months.

Upon discovering the attack, the company immediately took steps to prevent any further unauthorized activity and launched an investigation into the incident with the help of a forensic firm.

“We recently identified suspicious login activity to certain Chick-fil-A One accounts. Upon discovery of this activity, Chick-fil-A immediately took steps to prevent any further unauthorized activity, began an investigation, and engaged a national forensics firm.” reads the data breach notification sent to the impacted customers. “Following a careful investigation, we determined that unauthorized parties launched an automated attack against our website and mobile application between December 18, 2022 and February 12, 2023 using account credentials (e.g., email addresses and passwords) obtained from a third-party source. Based on our investigation, we determined on February 12, 2023 that the unauthorized parties subsequently accessed information in your Chick-fil-A One account.”

Threat actors behind the campaign targeted both the company website and mobile application.

What is credential stuffing?

“Credential stuffing is a type of attack in which hackers use automation and lists of compromised usernames and passwords to defeat authentication and authorization mechanisms, with the end goal of account takeover (ATO) and/or data exfiltration.” In other words, bad actors glean lists of breached usernames and passwords and run them against desired logins until they find some that work. Then, they enter those accounts for the purpose of abusing permissions, siphoning out data, or both. 

Chick-fil-A informed the impacted customers that the exposed information may have included their name, email address, Chick-fil-A One membership number and mobile pay number, QR code, masked credit/debit card number, and the amount of Chick-fil-A credit (e.g., e-gift card balance) on their account (if any). The exposed information may have included the month and day of birthday, phone number, and address in case the customers have saved them to their account.

The company pointed out that unauthorized parties would only have been able to view the last four digits of the customer’s payment card number.

Chick-fil-A required impacted users to reset their passwords, removed stored credit/debit card payment methods, and temporarily froze any funds that users might have loaded into their Chick-fil-A One accounts.

The company also restored customers’ Chick-fil-A One account balances, which included in some cases a refund to your original form of payment, where possible.

“As an additional way to say thank you for being a loyal Chick-fil-A customer, we have added rewards to
your account. Chick-fil-A continues to enhance its security, monitoring, and fraud controls as appropriate
to minimize the risk of any similar incident in the future.” concludes the data breach notification notice.

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Pierluigi Paganini

(SecurityAffairs – hacking, Chick-fil-A)