Athletic apparel brand Under Armour revealed on Thursday that data from around 150 million MyFitnessPal diet and fitness app accounts was compromised in February, according to a report in Reuters.
The stolen data includes account user names, email addresses and scrambled passwords for MyFitnessPal mobile app and website, Under Armour said in a statement. It added that Social Security numbers, driver license numbers and payment card data were not compromised.
According to SecurityScorecard, this is the largest data breach this year and one of the top five to date, based on the number of records compromised.
Larger hacks include 3 billion Yahoo accounts compromised in a 2013 incident and credentials for more than 412 million users of adult websites run by California-based FriendFinder Networks Inc in 2016, according to breach notification website LeakedSource.com, Reuters reported.
The firm said it is working with data security firms and law enforcement without sharing details on how the hackers compromised its network without getting caught.
Reuters said that while the breach “did not include financial data, large troves of stolen email addresses can be valuable to cyber criminals.”
Email addresses retrieved in a 2014 attack that compromised data on some 83 million JPMorgan Chase customers was later used in pump-and-dump schemes to boost stock prices, according to U.S. federal indictments in the case in 2015.
In an alert on its website, Under Armor urged MyFitnessPal users to change their passwords immediately.
The company said, “We continue to monitor for suspicious activity and to coordinate with law enforcement authorities.”
It added that it was strengthening systems that detect and prevent unauthorised access to user information.
Under Armour said it started notifying users of the breach on Thursday, four days after it first learned of the incident.
According to Reuters, Under Armour bought MyFitnessPal in 2015 for $475 million. It is part of the company’s connected fitness division, whose revenue last year accounted for 1.8 percent of Under Armour’s $5 billion in total sales.