This new iteration of Purple Fox that we came across, also being delivered by Rig, has a few new tricks up its sleeve. It retains its rootkit component by abusing publicly available code. It now also eschews its use of NSIS in favor of abusing PowerShell, making Purple Fox capable of fileless infection. It also incorporated additional exploits to its infection chain, most likely as a foolproof mechanism to ensure that it can still infect the system. Purple Fox is a downloader malware; besides retrieving and executing cryptocurrency-mining threats, it can also deliver other kinds of malware.Read More
Abusing PowerShell to deliver malware isn’t new; it’s actually a prevalent technique that many fileless threats use. We regularly encounter these kinds of threats, and Trend Micro behavior monitoring technology proactively detects and blocks them. We have smart patterns, for instance, that actively detect scheduled tasks created by malicious PowerShell scripts. We also have network rules that detect, for example, indications of activities like Server Message Block (SMB) vulnerabilities being exploited, potential brute-force attempts, and illicit cryptocurrency mining-related communications.
With that said, a sudden spike of these activities is unusual to us. Feedback from our Smart Protection Network™ revealed that this recent wave of attacks were mostly targeting China-based systems. The attacks, which are still ongoing, were first observed on May 17; the attacks peaked on May 22 and has since steadied.Read More
In early August we discussed a case where a backdoor (BKDR_ANDROM.ETIN) was being installed filelessly onto a target system using JS_POWMET.DE, a script that abused various legitimate functions. At the time, we did not know how the threat arrived onto the target machine. We speculated that it was either downloaded by users or dropped by other malware.Read More
As cybercriminals start to focus on pulling off attacks without leaving a trace, fileless malware will become a more common attack method. However, many of these malware are fileless only while entering a user’s system, as they eventually reveal themselves when they execute their payload. Attacks that use completely fileless malware are a rare occurrence, so we thought it important to discuss a new trojan known as JS_POWMET that uses a completely fileless infection chain making it more difficult for anti-malware engineers to examine.Read More
With additional analysis from David Agni Improvements in security file scanners are causing malware authors to deviate from the traditional malware installation routine. It’s no longer enough for malware to rely on dropping copies of themselves to a location specified in the malware code and using persistence tactics like setting up an autostart feature to…Read More