[HEADS UP] Recent Phishing Attacks Using PDF Files Have Skyrocketed More Than 1,000%

Here are two new recent trends in phishing attacks involving file attachments.  If you ever have any questions about files that you receive through email, please ask me or contact the help desk before downloading or opening them.

Phishing attacks using PDF files have spiked over the past year, according to researchers at Palo Alto Networks’ Unit 42.

“From 2019-20, we noticed a dramatic 1,160% increase in malicious PDF files – from 411,800 malicious files to 5,224,056,” the researchers write. “PDF files are an enticing phishing vector as they are cross-platform and allow attackers to engage with users, making their schemes more believable as opposed to a text-based email with just a plain link.”

The most common form of PDF phishing lures used an image of a fake CAPTCHA to trick victims into clicking the “Continue” button, which led to a malicious site. Another variant used an image that purported to be a coupon and told victims to click the image in order to get 50% off on a product.

The third type of PDF phishing attack used images that appeared to be paused videos but led to a phishing site when users clicked on them.

“These phishing files do not necessarily carry a specific message, as they are mostly static images with a picture of a play button ingrained in them,” Unit 42 says. “Although we observed several categories of images, a significant portion of them either used nudity or followed specific monetary themes such as Bitcoin, stock charts and the like to lure users into clicking the play button.”

RRU is noticing this trend.  We had several instances of identity theft at the start of the pandemic last year that started with a malicious link in a PDF file and, more recently, a malicious link in a PDF file was responsible for a staff member’s account being compromised back in December.

 

New Phishing Attack With .TXT Attachment

It had to happen… we’re now starting to see reports of the lowly .txt (text) file being used as a way to get malicious software onto your computer.  Here’s what they’re doing.

 

Initially, you’ll see an email message with an attachment with a name similar to “ReadMe_knl.txt.”  It may even have a Notepad icon associated with it, and it will open like a text file.  However, it will actually execute some code prepared by the attacker and download a malicious script from the Internet onto the computer.  After the script gets onto your computer, it can do a number of different things depending on what the particular attacker has set it up to do.

Bottom line: PLEASE be extra careful of EVERY file attached to an email, even the simple .txt file.  Even they’re not safe anymore.