Researchers have detected a brazen attack on restaurants across the United States that uses a relatively new technique to keep its malware undetected by virtually all antivirus products on the market.
Malicious code used in so-called fileless attacks resides almost entirely in computer memory, a feat that prevents it from leaving the kinds of traces that are spotted by traditional antivirus scanners. Once the sole province of state-sponsored spies casing the highest value targets, the in-memory techniques are becoming increasingly common in financially motivated hack attacks. They typically make use of commonly used administrative and security-testing tools such as PowerShell, Metasploit, and Mimikatz, which feed a series of malicious commands to targeted computers.
FIN7, an established hacking group with ties to the Carbanak Gang, is among the converts to this new technique, researchers from security firm Morphisec reported in a recently published blog post. The dynamic link library file it's using to infect Windows computers in an ongoing attack on US restaurants would normally be detected by just about any AV program if the file was written to a hard drive. But because the file contents are piped into computer memory using PowerShell, the file wasn't visible to any of the 56 most widely used AV programs, according to a Virus Total query conducted earlier this month.