authentication-in-the-middle phishing

Scammers can easily phish your multi-factor authentication codes. Here’s how to avoid it

More and more websites and services are making multi-factor-authentication (MFA) mandatory, which makes it much harder for cybercriminals to access your accounts. That’s a great thing. But as security evolves, so do cybercriminals who are always looking for new ways to scam us.

A type of phishing we’re calling authentication-in-the-middle is showing up in online media. While these techniques, named after man-in-the-middle (MitM) attacks, have existed for a while, they appear to be gaining traction now.

It works like this: A user gets lured to a phishing site masquerading as a site they normally use, such as a bank, email or social media account. Once the user enters their login into the fake site, that information gets redirected by the cybercriminals to the actual site, without the user knowing.

The user is then prompted for their MFA step. They complete this, usually by entering a code or accepting a push notification, and this information is then relayed to the criminals, allowing them to login to the site.

Once the criminals are into an account, they can start changing settings like the account’s email address, phone number, and password, so the user can no longer log in, or they can simply clean out a bank account. This may help you understand why many platforms ask for your PIN or other authentication again when you try to change one of these important settings.

Victims are lured to phishing sites like these via links from social media or emails where it can be hard to identify the real link.  Phishing sites can even show up in sponsored search results, in the same way as we reported about tech support scams.

How to protect yourself from authentication-in-the-middle attacks

  • Keep your wits about you. Being aware of how scammers work is the first step to avoiding them. Don’t assume sponsored search results are legit, and trust that if something seems suspicious then it probably is.
  • Use security software. Many security programs block known phishing sites, although domains are often short-lived and get rotated quickly. Malwarebytes Browser Guard can help protect you.
  • Use a password manager. Password managers will not auto-fill a password to a fake site, even if it looks like the real deal to you.
  • Consider passkeys. Multi-factor authentication is still super-important to enable, and will protect you from many types of attacks, so please continue to use it. However, authentication-in-the-middle attacks only work with certain types of MFA, and passkeys won’t allow the cybercriminals to login to your account in this way. Many services have already begun using passkeys and they’re no doubt here to stay.

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ABOUT THE AUTHOR

Pieter Arntz

Malware Intelligence Researcher

Was a Microsoft MVP in consumer security for 12 years running. Can speak four languages. Smells of rich mahogany and leather-bound books.