Hackers who normally distributed malware via phishing attachments with malicious macros gradually changed tactics after Microsoft Office began blocking them by default, switching to new file types such as ISO, RAR, and Windows Shortcut attachments.
VBA and XL4 Macros are small programs created to automate repetitive tasks in Microsoft Office applications, which threat actors abuse for loading, dropping, or installing malware via malicious Microsoft Office document attachments sent in phishing emails.
The reason for the switch is Microsoft announcing that they would end the massive abuse of the Office subsystem by automatically blocking macros by default and making it harder to activate them.
Although it took Microsoft a little longer to implement this Microsoft Office change, the block finally entered into effect last week.
In a new report by Proofpoint, researchers looked at malicious campaign stats between October 2021 and June 2022 and identified a clear shift to other methods of payload distribution, recording a decrease of 66% in the use of macros.
At the same time, the use of container files such as ISOs, ZIPs, and RARs has grown steadily, rising by almost 175%. The use of LNK files exploded after February 2022, the time of Microsoft’s announcement, increasing by a whopping 1,675% compared to October 2021, and being the weapon of choice of ten individual threat groups tracked by Proofpoint.