Attackers Discover New Options After Microsoft Macro Malware Blocking

A month after Microsoft started implementing its plan to dam macros from the web by default, risk actors are utilizing new malware supply strategies for spear phishing assaults that scale back their reliance on malicious macros.

Ole Villadsen, senior analyst on IBM Safety’s X-Pressure Menace Intelligence workforce, stated that since late final 12 months, he has noticed that attackers are more and more selling different downloaders or droppers that don’t depend on macros, together with XLL information, ISO photographs, Microsoft shortcut information. . and MSI information.

“These new file varieties have been used to distribute Emotet, Qakbot, JSSloader and different payloads,” he stated. “In some circumstances, attackers could also be experimenting with new file varieties to see how properly they work in comparison with earlier approaches primarily based on macros.”

For instance, in a low-volume Emotet marketing campaign in April, researchers noticed that attackers have been utilizing XLL information, a kind of dynamic hyperlink library (DLL) file designed to increase Excel’s performance. The marketing campaign confirmed marked modifications from the everyday habits of malware that beforehand exploited Microsoft Excel or Phrase paperwork containing VBA or XL4 macros. In an evaluation carried out in April, Proofpoint researchers estimated that TA542, the risk actor behind Emotet, is testing these new ways on a small scale earlier than making use of them on a wider stage.

“Along with Emot, we noticed quite a lot of actors utilizing XLL information to stage their payloads, together with these deploying different high-profile botnets or banking trojans like Qbot and Ursnif,” stated Sherrod DeGrippo, vice chairman of risk analysis and detection. with proofpoint. “Though not noticed since February, an unrelated risk actor has additionally used this system in campaigns to distribute Bazaloader, a malware linked to the distribution of high-profile Conti ransomware.”

Nonetheless, DeGrippo famous that macros are nonetheless in widespread use, and over the previous thirty days, greater than 1.5 million messages have been noticed containing a URL that has both hooked up a doc containing macros or led to it. As well as, the researchers stated that even earlier than Microsoft’s announcement, they’d already noticed common use of varied strategies that bypassed “mark of the online” detection.

“We have seen indications that sure, broadly used malware households have lately made some return to completely different distribution strategies that bypass modifications from doc downloaders.”

DeGrippo stated that along with XLL information, the usage of ISO information has additionally elevated.

“Whereas traditionally they’re extra carefully related to the supply of commodity malware reminiscent of Agent Tesla and FormBook, for the reason that February announcement, we’ve recognized a minimum of 7 actively monitored teams of actors that use information as a part of their supply chains. IcedID and the lately spawned Bumblebee. distribute extra subtle malware, reminiscent of installers,” he stated.

Microsoft has introduced for the primary time its plans to dam internet-derived macros by default for numerous Workplace purposes reminiscent of Entry, Excel, PowerPoint, Visio, and Phrase on gadgets working Home windows. The transfer was seen as a possible recreation changer in how attackers launch email-based assaults. Macros are applications written in Visible Primary for Functions (VBA) which are usually used to automate repetitive duties in Microsoft Workplace purposes. Nonetheless, cybercriminals took benefit of them with the last word purpose of delivering numerous malicious payloads or stealing delicate knowledge. Attackers simply have to ship an e mail to unknown locations with an Workplace attachment and persuade them to activate malicious macros.

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