Chemical Safety Incidents
Macro Malware on Way Back
Monday, May 23, 2016 @ 10:05 AM gHale
Once the rage, and since fallen out of fashion, macro malware is now evolving and coming back, researchers said.
Security researchers at Microsoft’s Malware Protection Center (MMPC) observed a new variation of the TrojanDownloader:O97M/Donoff family of Office-targeting macro-based malware in a file that contained a VBA project designed to script the malicious macro.
Active for several years, Donoff ends up used in spam email campaigns in which attackers employ social engineering techniques to trick users into opening malicious attachments. Donoff is a downloader where it drops other malware onto the infected system, including banking Trojans, point of sale threats, and ransomware.
In this latest iteration, Donoff developers make sure the attachment doesn’t appear malicious. The file is a Word document that contains seven VBA modules and a VBA user form with three buttons (using the CommandButton elements), Microsoft’s Marianne Mallen and Wei Li said in a blog post.
The researchers said the VBA modules appear to be legitimate SQL programs powered with a macro without malicious code.
When analyzing the other modules in the file, the researchers discovered unusual code in Module2 as well, where a macro was designed to decrypt the string in the Caption field for CommandButton3. The string ended up being a URL that would cull a payload containing the Locky ransomware.
Microsoft researchers also found the default autoopen() macro ende up used to run the entire VBA project as soon as the document opened.