Cyber criminal evades detection of Microsoft Office 365 phishing with HTML Lego pieces.

One of the most recent phishing campaign has used a trick of using chunks of HTML code that are stored remotely and locally to build fraudulent web pages that can collect Microsoft Office 365 credentials.

In this method, multiple pieces of HTML files are attached to JavaScript files that are used to act as a login page and lure the target to enter sensitive information.

The victims often get an email containing excel files that may contain HTML files having chunks of URL encoded text.

The JavaScript files contain two block of text that are encoded and contain URL, HTML code and Base64.

The security researchers decoded a total of 367 lines of HTML code which were divided in five chunks in two JavaScript files. They found an unusual trick where the JavaScript files are downloaded in separate chunks and then locally pieced together. This helps to bypass the security which can identify malicious JavaScript File and block it.           

Researchers have admitted that this trick is very uncommon and the criminals are able to evade detection to a great extent.


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