A risk actor has been abusing hyperlink wrapping companies from reputed know-how firms to masks malicious hyperlinks resulting in Microsoft 365 phishing pages that acquire login credentials.
The attacker exploited the URL safety function from cybersecurity firm Proofpoint and cloud communications agency Intermedia in campaigns from June by way of July.
Some e mail safety companies embrace a hyperlink wrapping function that rewrites the URLs within the message to a trusted area and passes them by way of a scanning server designed to dam malicious locations.
Legitimizing phishing URLs
Cloudflare’s Electronic mail Safety crew found that the adversary legitimized the malicious URLs after compromising Proofpoint and Intermedia-protected e mail accounts, and sure used their unauthorized entry to distribute the “laundered” hyperlinks.
“Attackers abused Proofpoint hyperlink wrapping in quite a lot of methods, together with multi-tiered redirect abuse with URL shorteners through compromised accounts,” the researchers mentioned.
“The Intermedia hyperlink wrapping abuse we noticed additionally targeted on gaining unauthorized entry to e mail accounts protected by hyperlink wrapping“ – Cloudflare Electronic mail Safety
The risk actor added an obfuscation layer by first shortening the malicious hyperlink earlier than sending it from a protected account, which routinely wrapped the hyperlink.
The researchers say that the attacker lured victims with pretend notifications for voicemail or shared Microsoft Groups paperwork. On the finish of the redirect chain was a Microsoft Workplace 365 phishing web page that collected credentials.
supply: Cloudflare Electronic mail Safety
Within the marketing campaign that abused Intermedia’s service, the risk actor delivered emails pretending to be a “Zix” safe message notification for a viewing a safe doc, or impersonated a communication from Microsoft Groups informing of a newly acquired message.
The hyperlink allegedly resulting in the doc was a URL wrapped by Intermedia’s service and redirected to a pretend web page from digital and e mail advertising platform Fixed Contact internet hosting the phishing web page.
Clicking on the reply button within the pretend Groups notification led to a Microsoft phishing web page that will acquire login credentials.
By disguising the malicious locations with official e mail safety URLs, the risk actor elevated the probabilities of a profitable assault, the Cloudflare researchers mentioned.
It ought to be famous that abusing official companies to ship malicious payloads shouldn’t be new however exploiting the link-wrapping safety function is a current growth on the phishing scene.
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