Halifax Bank scans the machines of surfers that land on its login page whether or not they are customers, it has emerged.

Security researcher Paul Moore has made his objection to this practice – in which the British bank is not alone – clear, even though it is done for good reasons. The researcher claimed that performing port scans on visitors without permission is a violation of the UK’s Computer Misuse Act (CMA).

Halifax has disputed this, arguing that the port scans help it pick up evidence of malware infections on customers’ systems. The scans are legal, Halifax told Moore in response to a complaint he made on the topic last month.

If security researchers operate in a similar fashion, we almost always run into the Computer Misuse Act, even if their intent isn’t malicious. The CMA should be applied fairly…

When you visit the Halifax login page, even before you’ve logged in, JavaScript on the site, running in the browser, attempts to scan for open ports on your local computer to see if remote desktop or VNC services are running, and looks for some general remote access trojans (RATs) – backdoors, in other words. Crooks are known to abuse these remote services to snoop on victims’ banking sessions.

Moore said he wouldn’t have an issue if Halifax carried out the security checks on people’s computers after they had logged on. It’s the lack of consent and the scanning of any visitor that bothers him. “If they ran the script after you’ve logged in… they’d end up with the same end result, but they wouldn’t be scanning visitors, only customers,” Moore said.

Halifax told Moore: “We have to port scan your machine for security reasons.”

Having failed to either persuade Halifax Bank to change its practices or Action Fraud to act (thus far1), Moore last week launched a fundraising effort to privately prosecute Halifax Bank for allegedly breaching the Computer Misuse Act. This crowdfunding effort on GoFundMe aims to gather £15,000 (so far just £50 has been raised).

Halifax Bank’s “unauthorised” port scans are a clear violation of the CMA – and amounts to an action that security researchers are frequently criticised and/or convicted for, Moore argued. The CISO and part-time security researcher hopes his efforts in this matter might result in a clarification of the law.

“Ultimately, we can’t have it both ways,” Moore told El Reg. “It’s either legal to port scan someone without consent, or with consent but no malicious intent, or it’s illegal and Halifax need to change their deployment to only check customers, not visitors.”

The whole effort might smack of tilting at windmills, but Moore said he was acting on a point of principle.

“If security researchers operate in a similar fashion, we almost always run into the CMA, even if their intent isn’t malicious. The CMA should be applied fairly to both parties.”

Source: Bank on it: It’s either legal to port-scan someone without consent or it’s not, fumes researcher • The Register