UK retail and commercial financial services giant Lloyds Banking Group has disclosed a data security incident impacting close to 450,000 of its mobile banking users.
The incident occurred on March 12 and was the result of a faulty software update that exposed transaction details from users’ current accounts to other users.
According to Lloyds, however, the transactions were exposed only if users were accessing their transaction lists simultaneously.
“In order to have seen another person’s transactions and for theirs to be potentially viewed by other customers, a customer had to access their own list of transactions within small fractions of a second of another person doing the same,” Lloyds told the UK’s Treasury Committee.
Lloyds said the glitched update was rolled out on March 12 at 03:28 and the issue was resolved at 08:08. The problem has not occurred since.
The types of data exposed in the incident vary depending on the actions taken by the users. Those who accessed the transaction lists could view information on other users’ transactions, including amounts, dates, and payment identifiers that could have included National Insurance numbers.
Users who clicked on individual transactions could have viewed information such as sort codes and account numbers, National Insurance numbers or vehicle registration numbers, and text entered in the reference fields.
“In some cases, the transaction information visible may have related to individuals who are not Lloyds Banking Group customers, for example in an instance where a payment was made from a Lloyds Banking Group customer account to an account holder at another bank,” Lloyds said.
The banking giant points out that users’ balances were not affected by the incident and that “customers were not able to perform unauthorised actions or move money on anyone else’s account.”
“Customers who experienced the issue would have been able to view others’ data momentarily, and the information that was visible would not be sufficient on its own for someone to carry out fraud against an individual’s bank account. Our assessment is that it is also very unlikely the information potentially viewed could be used to carry out fraudulent activity more widely,” Lloyds said.
The banking giant told the Treasury Committee that out of its 21.5 million mobile banking users 1.67 million logged in during the incident window, but only 447,936 customers were presented with other users’ transactions or had their transactions shown to others.
“We assess that a maximum of 114,182 customers clicked through to view the details behind individual current account transactions during that time and may have been presented with information about individual payments,” it said.
Lloyds also noted that it informed its customers of the incident via social media and that it paid roughly £139,000 (~$183,600) to around 3,625 customers, as “goodwill payments for distress and inconvenience.”
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