ZenRAT: Novel Malware Distributed Via Fake Bitwarden Installers

A new remote access trojan (RAT), ZenRAT, was found to be concealed within fake installation packages of the password manager, Bitwarden.

Primarily targeting Windows users, this information stealing malware was hosted on a fake website impersonating Bitwarden, researchers at Proofpoint revealed. Although, the mode of distribution was not confirmed. Based on similar past instances, it’s believed that victims were directed to the dubious domains via phishing emails, SEO Poisoning, and adware bundles.

The seemingly legitimate website selectively displays the fake Bitwarden download to Windows users, while non-Window users are redirected to a cloned opensource.com article on ‘How to Manage Your Passwords with Bitwarden, a LastPass Alternative.’’

Moreover, Windows users clicking on Linux or MacOS download links are redirected to the legitimate Bitwarden site.

The counterfeit installer was first reported on VirusTotal in July 2023, under a different name. Claiming to be ‘’Piriform’s Speccy,’’ a gathering system software application, the installer also pretended to have the digital signature of Tim Kosse, an open-source software developer known for the Filezilla FTP/SFTP software.

ZenRAT, posing as an ApplicationRuntimeMonitor.exe, upon execution uses WMI queries and other system tools to gather information about the system. It gathers data like, IP address, CPU, GPU, and RAM details, OS version, installed applications and antivirus software.

Subsequently, these details along with browser credentials/data are transferred to its command and control (C2) server using a unique C2 protocol.

ZenRAT is configured to support different Command IDs, used for transmitting its logs in plaintext to the C2 server. These logs disclose various checks performed by the malware, including mutex creation, anti-virtualization, system, and geo-restriction checks. The investigation further revealed that the malware was designed to be a ‘’modular, extendable implant.’’

To mitigate such threats, Proofpoint researchers advise users to be careful of software application ads that appear in search engine results. ‘’End users should be mindful of only downloading software directly from the trusted source, and always check the domains hosting software downloads against domains belonging to the official website.‘’