Several Polish banks have seen workstations infected with malware that appears to have originated from the country's financial regulator.

According to local press reports, a number of local banks last week began spotting unusual network activity and unauthorised files on their machines.

The issue seems to have been traced back to the webserver of the Polish Financial Supervision Authority where, thanks to a modification of one of the local JS files, an external JS file was loaded, executing malicious payloads on selected targets.

The watchdog - which is responsible for setting bank cybersecurity standards - confirmed to the Register that actors from outside Poland had compromised its systems. Its website was offline at pixel time.