Researchers from Palo Alto Networks uncovered a series of malicious spam campaigns using Agent Tesla malware. The attack starts with a socially engineered email designed to appear legitimate and relevant to the recipient. The email typically carries an archive attachment, which contains a JavaScript (JS) file that, once executed, triggers the initial infection stage. This file downloads a PowerShell script that sets the stage for further malicious activity.
PowerShell scripts are increasingly favored by cybercriminals due to their ability to evade traditional security systems. In this campaign, the PowerShell script delivers and executes Agent Tesla malware directly into system memory. By bypassing file-based detection, the malware executes without being detected by anti-virus software. It then injects itself into a legitimate process to mask its malicious actions and remain undetected.
To counter this, Symantec has strengthened its defenses through adaptive-based, behavior-based, and file-based detection strategies.
These include signatures specifically designed to catch PowerShell and Wscript-based attacks, such as ACM.Ps-CPE!g2 and ACM.Wscr-CNPE!g1. Symantec also employs SONAR technology to detect suspicious behaviors like unusual process launches or network activity. WebPulse-enabled products block domains and IPs associated with the malware, preventing further infections.
The sophistication of these attacks underscores the importance of comprehensive security strategies.
Organizations must focus on email filtering, script execution controls, and endpoint protection to mitigate advanced threats. Employees should receive regular training on recognizing and handling suspicious emails, which is crucial for preventing the initial infection stage and protecting against future threats.
