There is a new attack method in play these days that involves PowerPoint files and mouse over events, to get users to execute arbitrary code on their systems and download malware.
Malicious PowerPoint files use mouse over events to execute PowerShell code. These files, named “order.ppsx” or “invoice.ppsx,” end up going out via spam emails with subject lines such as “Purchase Order #130527” and “Confirmation.”
An analysis conducted by Ruben Daniel Dodge found when a PowerPoint presentation is opened, it displays the text “Loading…Please wait” as a hyperlink.
If the user hovers the mouse over the link, even without clicking it, the execution of PowerShell code ends up triggered. The Protected View security feature, which is enabled by default in most supported versions of Office, informs the user of the risks and prompts them to enable or disable the content.
If the victim enables the content, the PowerShell code is executed and a domain named “cccn.nl” ends up contacted. A file is downloaded from this domain and executed, ultimately resulting in the deployment of a malware downloader.
Researchers at SentinelOne also looked at the attack and found it delivered a new variant of the banking Trojan, Zusy, Tinba and Tiny Banker.
The security firm said the attack does not work if the malicious presentation is opened using PowerPoint Viewer, and most versions of Office warn the user before the code executes, the method could still be efficient in some cases.
“The PowerPoint viewer doesn’t seem to be vulnerable at all because it refuses to execute the program,” SentinelOne Labs researchers said in a blog post.
“Users might still somehow enable external programs because they’re lazy, in a hurry, or they’re only used to blocking macros. Also, some configurations may possibly be more permissive in executing external programs than they are with macros,” the researchers said.