Pierluigi Paganini July 15, 2024

Cybersecurity researchers detailed a new version of the HardBit ransomware that supports new obfuscation techniques to avoid detection.

The new version (version 4.0) of the HardBit ransomware comes with the Binary Obfuscation Enhancement with passphrase protection.

The ransomware requires the passphrase to be entered at runtime to be executed. Furthermore, additional obfuscation complicates the analysis for security researchers.

The HardBit ransomware group offers its malware in CLI and GUI versions. The GUI version is more user-friendly, making it easier for less technically skilled operators to execute. The delivery method involves the Neshta virus, with the ransomware itself being a .NET binary. The malware is obfuscated using a packer called Ryan-_-Borland_Protector Cracked v1.0, which is a custom version of the open-source .NET packer ConfuserEx.

The HardBit ransomware group first appeared on the threat landscape in October 2022, but unlike other ransomware operations, it doesn’t use a double extortion model at this time.

The gang threatens victims of further attacks if their ransom demands are not met. Once infected the network of an organization, the HardBit ransomware group instructs victims to contact them by email or via the Tox instant messaging platform.

The group made the headline because it seeks to negotiate with victims to settle.

In order to make it impossible for the victims to recover the encrypted files, the ransomware deletes the Volume Shadow Copy Service (VSS) using the Service Control Manager and the Windows backup utility catalog along with any shadow copies.

The researchers noticed that the malware encrypts many files, potentially causing errors when Windows is restarted. To avoid problems at the successive startup, the malware edits the boot configuration to enable the “ignore any failures” option and disable the recovery option.

To prevent Windows Defender Antivirus from blocking the ransomware process, it makes several Windows Registry changes to disable many Windows Defender features (i.e. tamper protection, anti-spyware capabilities, real-time behavioral monitoring, real-time on-access (file) protection, and real-time process scanning).

The ransomware achieves persistence by copying a version to the victim’s “Startup” folder, if not already present. The executable filename mimics the legitimate service host executable file, svchost.exe, to avoid detection.

The initial access method used by the HardBit Ransomware group is still unknown; however, experts at Cybereason pointed out that it follows similar methodologies associated with other ransomware operations.

HardBit shares several similarities with LockBit Ransomware, including group name, image/icons, fonts, and ransom notes. At this time, it is unclear if there is a link between HardBit and LockBit, experts speculate these similarities may be part of HardBit’s marketing tactics.

“While the initial attack vector remains unconfirmed at the time of this writing, Cybereason hypothesizes that the threat actors gain an initial foothold into the victim’s environment through brute force of an open RDP and SMB service. In fact, the environment observed multiple login failures from known brute forcing IP addresses.” reads the report published by Cybereason.

Threat actors employ credential theft tools, like Mimikatz and the RDP brute-forcing tool NLBrute, in lateral movement activities. The attack starts by deploying a zip file named 111.zip, which included a BAT script (!start.bat) and Mimikatz binaries. Upon execution, Mimikatz ran through the !start.bat script, producing an output file, Result.txt, with the dumped credentials. This output was then parsed and formatted by a script called miparser.vbs.

The operators rely on the file infector Neshta to deploy HardBit for encryption.

HardBit can disable Microsoft Defender Antivirus and inhibit System Recovery. It can terminate processes and services to evade detection, experts warn that version 3.0 and 4.0 also support wiper mode.

The report provides additional info on the ransomware, including the MITRE ATT&CK MAPPING.

Pierluigi Paganini

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(SecurityAffairs – hacking, malware)