Avast today released its Q3/2021 Threat Report. In the third quarter of the year, the Avast Threat Labs have seen an increased risk of businesses and consumers being attacked by ransomware and remote access trojans (RATs). RATs can be used for industry espionage, credentials theft, stalking, and even distributed denial of service (DDoS) attacks. The threat researchers also observed innovation in the ever-evolving cybercrime space, with new mechanisms used by exploit kits, and by the mobile banking Trojan Flubot.
Ransomware and RATs putting businesses at risk
In the beginning of Q3 2021, the world witnessed a massive supply chain attack on IT management software provider Kaseya and its customers, with Sodinokibi/REvil ransomware. The Avast Threat Labs noticed and blocked this attack on more than 2.4k endpoints. Following the involvement of politics, the ransomware operators released the decryption key, and Sodinokibi’s infrastructure went down, with no new variants seen in the wild until September 9th, when Avast detected, and blocked, a new variant. Overall, in Q3, the Avast Threat Labs saw the risk ratio of ransomware attacks go up by 5% vs. Q2, and even up by 22% vs. Q1 2021.
RATs were also a dangerous threat for businesses and consumers, which spread further in Q3 than in the previous quarters. Avast spotted three new RAT variants, including FatalRAT with anti-VM capabilities, VBA RAT, which exploits the Internet Explorer vulnerability CVE-2021-26411, and a new version of Reverse RAT with build number 2.0 which added web camera photo taking, file stealing and anti-AV capabilities. “RATs can be a fundamental threat for businesses, as they can be used for industry espionage,” said Jakub Kroustek, Avast Malware Research Director. “However, RATs can also be used against consumers, for example to steal their credentials, to add their computers to a botnet to drive DDoS attacks, and unfortunately, for cyberstalking, which can do massive harm to an individual’s privacy and wellbeing.”
Growing distribution of rootkits, and innovation in exploit kits and mobile banking trojans
The Avast Threat Labs also recorded a significant increase in rootkit activity at the end of Q3, which was one of the most significant increases in activity in the quarter. A rootkit is malicious software designed to give unauthorized access to cybercriminals, with the highest system privileges. Rootkits commonly provide services to other malware in the user mode.
Another malware category that appears to be returning are Exploit Kits, with notable new innovations occurring, including the targeting of Google Chrome vulnerabilities. The most active exploit kit was PurpleFox, against which Avast protected over 6,000 users per day on average. Rig and Magnitude were also prevalent throughout the whole quarter. The Underminer exploit kit woke up after a long period of inactivity and started sporadically serving HiddenBee and Amadey. Some exploit kits, especially PurpleFox and Magnitude, are under heavy development, regularly receiving new features and exploitation capabilities.
The Avast Threat Labs also monitored new tactics on the mobile front, with FluBot, an Android SMS banking threat, changing its social engineering approach. Jakub Kroustek said, “Flubot first spread posing as delivery services to lure the victims into downloading a “tracking app” for a parcel they recently missed or should be expecting. In Q3, Avast has seen novel scenarios in spreading this malware. One example is posing as voicemail recorders. Another is fake claims of leaked personal photos. The most extreme of these variants would even lure the victim to a fake page that would claim the victim has already been infected by FluBot when they probably weren’t yet and trick them into installing a “cure” for the “infection”. This “cure” would in fact be the FluBot malware itself.”
