Phishing Risks in Gmail’s New “Confidential Mode”

In my previous post — “New Gmail Features That May Be ILLEGAL for You to Use!” (https://lauren.vortex.com/2018/05/05/new-gmail-features-that-may-be-illegal-for-you-to-use), I noted that I’m very pleased overall with Google’s new Gmail, but also explained how using specific features of new Gmail — in particular “confidential mode” — may have negative legal implications for some users, especially those with legally-mandated data retention requirements.

But there’s another potential issue with “confidential mode” that could be a much broader risk to many more persons — the possibility that this mode will be leveraged by crooks for a new wave of phishing emails designed to spread malware and steal personal information.

The problem arises since non-Gmail users cannot directly receive Gmail confidential mode messages. Instead — as reported in the article that I linked to in my previous post — when a Gmail user wants to send a non-Gmail user such a message, the non-Gmail user is instead sent a link, that when clicked takes them to Google’s servers where they can read the confidential mode message in their browser.

The potential risks for any service that operates in this way are obvious.

Those of us working on Internet security and privacy have literally spent many years attempting to train users to avoid clicking on “to read the message, click here” links in emails that they receive. Criminals have simply become too adept at creating fraudulent emails that lead to phishing and malware sites.

Our efforts have had only limited success. Millions of busy users even click on such fake links in messages that are not even particularly “well crafted” or seem “obviously” fake as viewed by those of us who have long been dealing with such issues.

Any email system that depends on users clicking on emailed links to access remotely hosted email messages is likely to be subject to such criminal abuses. No matter how much diligence Google employs to try avoid users being fooled by phishing messages masquerading as links to Gmail confidential mode messages, we can be reasonably sure that this could ultimately represent a significant new vector of attack for phishing operations that will successfully ensnare large numbers of Internet users over time.

Given the relatively poor success that educational and message authentication efforts have had to date in these respects, there are no obvious solutions immediately apparent if Google operates their Gmail confidential mode in the manner described.

–Lauren–