Khosrow Zarefarid, a former employee of Iran-based Eniak, discovered the security hole in Iranís banking system and informed of it the executives of the affected banks, substantiating his claims with account information from a thousand of their customers.
After not having received any reply or even a simple acknowledgement of awareness of the problem, he hacked 3 million bank accounts and made public the users' details, card numbers and PINs.
The affected banks reacted differently to this development. At least three of them notified their clients of the need to change their debit card PINs. Some blocked their clients' accounts just in case.
A warning from the Central Bank of Iran asking bank customers to change their PINs is being repeatedly played on the state TV channels, and many of the ATMs in the country are currently only allowing the users to change their PINs.
According to ZDNet's Emil Protalinski, the Central Bank of Iran and the affected banks have not yet said whether the security hole has been closed in the meantime.