April 23, 2024

New BEC cyberattacks use phishing with a professional Dropbox hyperlink as a lure for malware and credentials theft.

This illustration shows a lock, unlocked over a person at a keyboard.
Picture: Adobe Inventory.

Risk actors have added a brand new wrinkle to conventional enterprise electronic mail compromise cyberattacks. Name it BEC 3.0 — phishing assaults that bury the hook in professional internet providers like Dropbox.

Avanan, a unit of Test Level Software program, has tracked a current instance of this assault household, through which hackers created free Dropbox accounts to seize credentials or cover malware in legitimate-looking, contextually related paperwork akin to potential workers’ resumes.

The assault, the safety agency found, began with the actors sharing a PDF of somebody’s resume through Dropbox. The goal can’t view the doc except they Add To Dropbox. The hyperlink from Dropbox seemed professional, making the exploit tougher to identify.

The phishing exploit entails these steps:

  • First, a person clicks the hyperlink in a professional notification from Dropbox to a resume and accesses a web page hosted on the file-sharing service.
  • The person should then enter their electronic mail account and password to view the doc. Because of this the menace actors have entry to electronic mail addresses and passwords.

On this web page hosted on Dropbox, customers are requested to enter their electronic mail account and password to view the doc, giving menace actors person credentials.

As soon as a person enters their credentials, they’re directed to a faux Microsoft OneDrive hyperlink. By clicking on the hyperlink, customers are given a malicious obtain.

“We’ve seen hackers do plenty of BEC assaults,” Jeremy Fuchs, a cybersecurity researcher/analyst at Avanan, mentioned in a report on the assault. “These assaults have a number of variations, however usually they attempt to spoof an govt or accomplice to get an finish person to do one thing they don’t need to do (like pay an bill to the incorrect place),” he mentioned.

SEE: One other hide-the-malware assault focuses on DNS (TechRepublic)

“Leveraging professional web sites to host malicious content material is a surefire option to get into the inbox,” he mentioned. “Most safety providers will have a look at the sender — on this case, Dropbox — and see that it’s professional and settle for the message. That’s as a result of it’s professional,” he added.

Avanan mentioned stopping these stealth assaults requires numerous defensive steps, together with scanning for malicious recordsdata in Dropbox and hyperlinks in paperwork, in addition to changing hyperlinks within the electronic mail physique and inside attachments. The important thing to schooling in opposition to these social engineering assaults is context, in response to Fuchs: “Are resumes usually despatched through Dropbox? If not, it could be a motive to contact the unique sender and double-check. If they’re, take it one step additional. Once you log into Dropbox, do I’ve to log in once more with my electronic mail?”

Avanan mentioned the researchers reached out to Dropbox on Could 15 to tell them of this assault and analysis.

Linktree additionally used to seize credentials

Earlier this month, Avanan found the same hack utilizing the social media reference touchdown web page Linktree, which is hosted on websites like Instagram and TikTok. Much like the Dropbox assaults, hackers created professional Linktree pages to host malicious URLs to reap credentials.

The attackers despatched targets spoofed Microsoft OneDrive or SharePoint notifications {that a} file has been shared with them, instructing them to open the file, in response to Avanan. Finally, the person is redirected to a faux Workplace 365 login web page, the place they’re requested to enter their credentials, the place their credentials are stolen.

“[Users] ought to assume: Why would this individual ship me a doc through Linktree? Probably, that wouldn’t be the case. That’s all part of safety consciousness — understanding if an electronic mail or course of appears logical,” mentioned Fuchs.

In these circumstances, the agency means that recipients:

  • At all times verify the sender’s deal with earlier than replying to an electronic mail.
  • Cease and assume if the medium getting used to ship a file is typical.
  • When logging right into a web page, double-check the URL to see if it’s Microsoft or one other professional web site.

BEC assaults utilizing professional websites might escalate this yr

Fuchs mentioned there aren’t any apparent visible cues to tip off assault recipients to BEC exploits. “Though when you have been to signal into the Dropbox web page, you’d see that there’s a OneDrive emblem and hyperlink,” he mentioned. “Eagle-eyed customers ought to discover that discrepancy and assume—why would there be two competing providers on one web page?,” he added.

He predicted that these assaults will escalate. “Any common service that’s legit can doubtlessly be used as a automobile to ship any such malicious exercise. That’s why we anticipate it to take off within the close to future,” he mentioned, including that the exploit has been used tens of 1000’s of occasions. “We imagine it will actually take off in quantity within the second half of the yr,” he mentioned.