A new variant of the Agent Tesla spyware has been spreading via malicious Microsoft Word documents, Fortinet reports.
The malware was initially detailed last June, when security researchers discovered it was spreading via a Microsoft Word document containing an auto-executable malicious VBA Macro. When opening the document, users were asked to “enable content,” which resulted in the spyware being covertly installed if they did so.
The malicious documents observed in the recent campaign instead ask the victim to double click a blue icon to enable a “clear view.” This action, however, results in a POM.exe file being extracted from the embedded object, which is saved to the system’s temporary folder and executed.
The POM.exe executable is written in Visual Basic and acts as an installer, Fortinet’s Xiaopeng Zhang reveals.
The Agent Tesla spyware was designed to collect keystrokes, system clipboard, screenshots, and credentials from a variety of installed software. To perform its nefarious activities, the malware creates different threads and timer functions in the main function.
The new malware variant has the same capabilities as the previously observed version, but uses SMTPS to send the collected data to the attacker’s email box, instead of HTTP POST requests.
“Based on my analysis, the commands used in the SMTP method include ‘Passwords Recovered’, ‘Screen Capture’, and ‘Keystrokes’, etc. The commands are identified within the email’s ‘Subject’ field,” the security researcher explains.
To receive the stolen information, the attacker registered a free Zoho email account for this campaign. The email service provider has been informed on the abuse, Fortinet says.