Phishing Attacks That Bypass MFA Could Become The Norm

Multi-factor authentication (MFA) is now a standard cybersecurity practice—or at least it should be—across an organization’s IT environment. MFA has been proven to stop hackers from accessing accounts and thwart ransomware attacks from happening with compromised credentials alone.

However, like with most IT security safeguards, cybercriminals are finding ways around it with phishing attacks that bypass MFA, according to new research from cybersecurity firm Proofpoint.

Phishing kits are evolving to be able to steal those tokens and bypass MFA with tools that leverage transparent reverse proxy, enabling them to man-in-the-middle a browser session and steal credentials and session cookies in real time.

According to Proofpoint, these kits no longer use a phony website, but instead use a transparent reverse proxy to present the actual website to the victim. Since modern websites frequently change, presenting the actual site enhances the illusion that the login is legitimate.

This also allows the hacker to man-in-the middle (MitM) a session and capture not only usernames and passwords, but also the session cookie that allows the threat actor to access the targeted account with the need for credentials or MFA tokens.

The company says it has observed three transparent reverse proxy kits being used in the wild, and greater adoption is anticipated as more organizations adopt multi-factor authentication methods.

The company, citing research from Stony Brook University and Palo Alto Networks, says MitM phishing kids are an industry blind spot. Those researchers identified over 1,200 MiTM phishing websites, the majority of which don’t appear on popular blocklists.

Further, MitM phishing sites can last several days, whereas standard phishing sites only last about a day.

As more organizations embrace layered security, threat actors will move to new solutions, like these MitM phishing attacks that bypass MFA, Proofpoint says.

“They are easy to deploy, free to use, and have proven effective at evading detection,” the company writes in a blog. “The industry needs to prepare to deal with blind spots like these before they can evolve in new unexpected directions.”

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