A series of email-based malware distribution campaigns is targeting businesses with multiple malware payloads that include Gozi ISFB, ZLoader, SmokeLoader, and AveMaria, researchers say.
The Cisco Talos team has been watching attackers launch these campaigns over the past several months and reports they employ several techniques designed to evade detection and maximize effectiveness. In most instances, attackers begins communication with potential victims by using contact forms on the target organization's website.
"This results in email communications that appear to originate from legitimate sources which may allow the adversaries to evade some email security mechanisms," researchers explain.
The attackers claim to be the copyright owner of images they found on the target website. The emails are somewhat customized and include the organization's domain as the website with copyrighted content, as well as a hyperlink the victim is prompted to click. In most emails, this leads to a malicious file hosted on Google Drive. Researchers note using a legitimate platform may also help adversaries evade email protections.
These documents contain macros that start the infection process, in which a malicious payload is executed on the target system. While the attackers have delivered several different malware families in each campaign, all have the same crypter in each initial payload. The presence of a specific string value, "Salfram," has made it easy for researchers to track the activity over time, they say, and this crypter has undergone development to make analysis more difficult.
Read the full report for more details.