Reg reader Matt Freeman said he was prompted with a SSL certificate warning from a domain called 'www.polycache.com' when attempting to log in to Alliance & Leicester's online banking Internet using FireFox 4.
Alarmed by the incident, Matt did some digging and discovered that the warning stemmed from a script from advanced-web-analytics.com that, in turn, downloads another script from polycache.com.
Polycache.com was only registered a few weeks ago and is hosted by virtual server hosting firm lineode.com, a legitimate firm but not one normally associated with hosting e-commerce systems for high street banks. Domain registration details for polycache are hidden. In addition, polycache.com doesn't have a home page.
All this looks rather suspicious if not necessarily malicious. Rik Ferguson, a security consultant at Trend Micro said: "This doesn't look like the infrastructure for a bank."
Ferguson said the set-up more closely resembles the prelude to a possible attack. He said nothing has been stolen as of Tuesday afternoon but the set-up "looks suspicious and it would take only one additional script to do something bad".
Freeman and others have begun debating the issue on Linode.com forums and elsewhere. Freeman has posted a detailed explanation of his worries here. Other Reg readers have separately been in touch with their concerns.
Santander blamed the glitch on a "technical failure" at an unnamed third party online banking partner, which has since been resolved. It stressed that customer data was never at risk, saying that worries to the contrary were "unfounded".
Santander's internet banking systems utilise a number of third parties and one of these appears to have had a technical failure. This has been investigated fully and rectified.
Santander can confirm that neither its website nor the A&L website have been hacked. Customer data has not been compromised.
We asked Santander for a clearer explanation of what the "technical failure" might be. A spokeswoman told us that since this covered a fraud and security issue they were not going to say what it is, but she was able to repeat the assurance that customer data was safe.
Which is nice. ®