Trend Micro security experts discovered a sophisticated cyberattack that included social engineering tactics and commonly employed remote access tools. The attack, which uses stealthy infostealer malware, gives thieves permanent access over vulnerable PCs and allows them to steal sensitive data.
According to Trend Micro Threat Intelligence, the majority of incidents since October 2024 have been concentrated in North America, with 21 breaches reported. The US was the most affected, with 17 cases, followed by Canada and the United Kingdom, each with five. Europe documented a total of 18 incidents.
Modus operandi
Threat actors utilise social engineering techniques to acquire initial access by deceiving victims into submitting credentials. Microsoft Teams is used for impersonation, and Quick Assist and other remote access applications allow attackers to escalate privileges. OneDriveStandaloneUpdater.exe, a genuine OneDrive update application, is used to sideload malicious DLLs and grant attackers network access.
Subsequently, the attackers install BackConnect malware, which allows them to keep control of affected systems. Malicious files are hosted and propagated via commercial cloud storage services, leveraging misconfigured or publicly available storage buckets.
The BackConnect malware has been linked by researchers to QakBot, a loader malware that was the focus of the 2023 takedown effort called "Operation Duckhunt." Access to target computers by Black Basta ransomware attackers was made possible in large part via QakBot. After it was taken down, these threat actors switched to alternative methods to continue operating.
Black Basta and Cactus ransomware link
Trend Micro analysts recently investigated cases in which the Black Basta and Cactus ransomware perpetrators used the identical BackConnect malware. This malware allows cybercriminals to execute commands remotely, steal credentials, and steal financial information.
In 2023, Black Basta alone extorted $107 million from victims, with manufacturing the largest hit, followed by financial sectors and real estate. Attackers also utilised WinSCP, an open-source file transfer client, to move data within infected systems. The infected files were first acquired from a cloud storage provider before being repackaged and distributed using system vulnerabilities.
Further investigation into Black Basta's internal chat breaches indicates that members of the gang are now using Cactus ransomware. Researchers believe that this transition will allow Cactus to remain a major threat by 2025.
