Unmasking Agent Tesla: A Deep Dive into a Multi-Stage Campaign
Essential information
- Published
- 25/02/2026 20:01
- Modified
- 25/02/2026 20:56
- Tags
- 2026-02-25 agent-tesla anti-analysis credential harvesting data exfiltration in-memory execution multi-stage attack phishing process-hollowing smtp
- Related entities
- 4 observables, 1 intrusion sets (apt), 9 techniques (mitre), 1 others
Description
This analysis examines a sophisticated multi-stage infection chain utilizing Agent Tesla malware. The attack begins with a phishing email containing a RAR file, which includes an obfuscated JSE file. This initial stage triggers a series of script-based evasions, leading to the download and decryption of a PowerShell script. The malware then employs process hollowing to inject its payload into a legitimate Windows process, evading detection. Before exfiltrating data, the malware performs anti-analysis checks to avoid security software and virtual environments. Finally, Agent Tesla harvests sensitive information, including browser cookies and contacts, exfiltrating the data via SMTP to a command-and-control server.