Hackers Leverage Microsoft Teams to Spread Matanbuchus 3.0 Malware to Targeted Firms

Cybersecurity researchers have flagged a new variant of a known malware loader called Matanbuchus that packs in significant features to enhance its stealth and evade detection.

Matanbuchus is the name given to a malware-as-a-service (MaaS) offering that can act as a conduit for next-stage payloads, including Cobalt Strike beacons and ransomware.

First advertised in February 2021 on Russian-speaking cybercrime forums for a rental price of $2,500, the malware has been put to use as part of ClickFix-like lures to trick users visiting legitimate-but-compromised sites not running it.

Matanbuchus stands out among loaders because it’s not usually spread through spam emails or drive-by downloads. Instead, it’s often deployed using hands-on social engineering, where attackers trick users directly. In some cases, it supports the kind of initial access used by brokers who sell entry to ransomware groups. This makes it more targeted and coordinated than typical commodity loaders.

The latest version of the loader, tracked as Matanbuchus 3.0, incorporates several new features, including improved communication protocol techniques, in-memory capabilities, enhanced obfuscation methods, CMD and PowerShell reverse shell support, and the ability to run next-stage DLL, EXE, and shellcode payloads, per Morphisec.

The cybersecurity company said it observed the malware in an incident earlier this month where an unnamed company was targeted via external Microsoft Teams calls that impersonated an IT help desk and tricked employees into launching Quick Assist for remote access and then executing a PowerShell script that deployed Matanbuchus.

It’s worth noting that similar social engineering tactics have been employed by threat actors associated with the Black Basta ransomware operation.

“Victims are carefully targeted and persuaded to execute a script that triggers the download of an archive,” Morphisec CTO Michael Gorelik said. “This archive contains a renamed Notepad++ updater (GUP), a slightly modified configuration XML file, and a malicious side-loaded DLL representing the Matanbuchus loader.”

Matanbuchus 3.0 has been advertised publicly for a monthly price of $10,000 for the HTTPS version and $15,000 for the DNS version.

Once launched, the malware collects system information and iterates over the list of running processes to determine the presence of security tools. It also checks the status of its process to check if it’s running with administrative privileges.

It then sends the gathered details to a command-and-control (C2) server to receive additional payloads in the form of MSI installers and portable executables. Persistence on the shot is achieved by setting up a scheduled task.

“While it sounds simple, Matanbuchus developers implemented advanced techniques to schedule a task through the usage of COM and injection of shellcode,” Gorelik explained. “The shellcode itself is interesting; it implements a relatively basic API resolution (simple string comparisons), and a sophisticated COM execution that manipulates the ITaskService.”

The loader also comes fitted with features that can be invoked remotely by the C2 server to collect all executing processes, running services, and a list of installed applications.

“The Matanbuchus 3.0 Malware-as-a-Service has evolved into a sophisticated threat,” Gorelik said. “This updated version introduces advanced techniques such as improved communication protocols, in-memory stealth, enhanced obfuscation, and support for WQL queries, CMD, and PowerShell reverse shells.”

“The loader’s ability to execute regsvr32, rundll32, msiexec, or process hollowing commands underscores its versatility, making it a significant risk to compromised systems.”

As malware-as-a-service evolves, Matanbuchus 3.0 fits into a broader trend of stealth-first loaders that rely on LOLBins (living-off-the-land binaries), COM object hijacking, and PowerShell stagers to stay under the radar.

Threat researchers are increasingly mapping these loaders as part of attack surface management strategies and linking them to abuse of enterprise collaboration tools like Microsoft Teams and Zoom.

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Some parts of this article are sourced from:
thehackernews.com