Phishers Use Blank Images to Disguise Malicious Attachments

Security researchers have noticed another ground breaking strategy phishing actors are applying to bypass traditional security filters – this time working with blank photos.

The email in concern was detected by Check Issue business Avanan, and arrived as a legitimate-searching DocuSign concept.

Despite the fact that the connection in the email entire body will get the person instantly to a regular DocuSign web site, the HTML attachment at the base was more suspect.

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The HTML file in query contained an SVG impression encoded with Foundation64.

“At the main, this is an vacant picture with energetic information inside of. In truth, there is JavaScript inside of the image. This redirects automatically to the destructive URL,” reported Avanan.

“Essentially, the hackers are hiding the malicious URL inside an empty graphic to bypass classic scanning companies.”

Clicking on the hyperlink would automatically take the consumer to a destructive web-site.

“This is an innovative way to obfuscate the genuine intent of the concept,” the security vendor concluded.

“It bypasses VirusTotal and does not even get scanned by regular Click on-Time Defense. By layering obfuscation upon obfuscation, most security providers are helpless against these attacks.”

It can be observed as a variation on a preceding “MetaMorph” attack noticed by Avanan quite a few decades ago, in which phishing actors use “meta refresh” to redirect the user from the HTML attachment hosted domestically to a phishing page on the community internet. A meta refresh is performance that instructs a web browser to automatically refresh the recent web web site after a supplied time interval.

To mitigate the menace, security admins are urged to be suspicious of, or outright block, HTML or .htm attachments in any inbound e-mails – dealing with them successfully like executables.