Tesco banks has recently announced that it has seen “suspicious transactions” from around 40,000 accounts over the weekend, and this has led them to actually shut down their site while they look into it. At the moment of writing it is not known how much (if any) money was taken from the 20,000 of the aforementioned 40,000 account where withdrawals were attempted.
This has been called a much more recent and unique attack since most of the time when a bank is hacked only the larger accounts are compromised, and the attackers don’t bother with smaller accounts, in order to avoid a better chance of getting caught. This also means that a hacked bank doesn’t have to shut down their site to investigate it, though in this instance it was so widespread the bank itself had to briefly shut down.
Apparently it is suspected that intruders found their way in via either a bug that was introduced with a website update, or through some third party connected to Tesco, as the attack was clearly done to the website, and not the core computer systems that provide most of the heavy lifting for the bank’s systems.