Summary
Netskope Threat Labs recently discovered a phishing campaign that is abusing Adobe Acrobat to host a Microsoft Office phishing page. While abusing free cloud services to host malicious content is a popular attack technique, this is the first time we have seen Adobe Acrobat used to deliver malicious content.
The attack starts with a phishing email that lures the user into opening a PDF file that redirects them to an Adobe Acrobat URL. This URL is hosting a malicious HTML page, which aims to steal Microsoft Office usernames and passwords. Once the victim enters the credentials in the phishing form, they are sent to a PHP page hosted on another website.
Below, is a diagram to illustrate how this attack works:
In January 2022, a similar attack was spotted, where attackers were abusing Adobe Creative Cloud to host malicious PDF files. In the recent campaign spotted by Netskope Threat Labs, attackers are instead abusing Adobe Acrobat to host the malicious HTML files.
Different from Adobe Creative Cloud, attackers can easily create free trial accounts in Adobe Acrobat without having to provide credit card numbers or any additional personal information. Once the account is created, the attackers can host and publicly share files. Netskope Threat Labs tested this technique by creating a free trial account in Adobe Acrobat, then uploading and sharing an HTML file in less than 2 minutes.
In this blog post, you will find more details about how this attack works.
Details
The attack starts with a phishing email that lures the user into opening an attached PDF file, disguised as a payment receipt. This is a very common social engineering technique that tries to draw the attention of the victim with a fake document related to money, such as an invoice or a receipt.