The OnyxC2 stealer surfaced on a cybercrime network earlier this year and is available through Malware-as-a-Service (MaaS) for hire starting at $250 per month.
The rental price for OnyxC2 is at the higher end of stealer costs. This is primarily justified by its stealth and reach. The developers offer several options: ’normal’ at $250 per month, and ‘premium’ (which includes HNVC) at $500 per month); and are sufficiently confident to offer refunds if the build gets detected.
A third option is described as ‘private’: “Source code + installation guide and we can install it for you if you don’t have knowledge. Only 6k$.” This last option doesn’t specify a monthly price. The implication is that it is an outright purchase, but this is also not specified.
Researchers at BlackFog obtained and analyzed two samples of the stealer. “It is software sold and supported like a commercial product, which is what puts a capable stealer in the hands of buyers who could never write one,” they write. To further assist such users, the package also includes several ready-made lures, including FinePrint, SystemSettings, fake Windows update packages, and for gamers (and who isn’t?), Fling-Standalone.
The OnyxC2 reach is extensive. The developers claim access to 37 Chromium-based and 8 Gecko-based browsers; 95 Chromium and 14 Gecko extensions (including 6 dedicated two-factor authentication extensions); five password managers, 17 cryptocurrency wallets, 11 FTP clients, and 5 email clients; with a further set of VPN, remote access, messaging, note-taking, and gaming targets. Altogether, says BlackFog, that is roughly 210 applications and extensions across nine categories.
It adds, “A stealer that scrapes password managers and 2FA extensions alongside saved logins is built to collect the credentials and session material that survive a password reset. The FTP and email targets push it past consumer credential theft and into the business systems that small finance and operations teams rely on every day. One infected host shown in the panel had already surrendered 55 saved passwords, 4,717 cookies, 719 autofill entries, 2 cards, and a wallet.” We should also add persistence to reach and stealth.
The stealer is paired with a remote-access toolkit and provides HVNC over a web browser, LSASS dumping, RunPE in memory and on disk, a reverse SOCKS5 proxy, screenshot capture, a keylogger, a file manager, and a reverse shell over HTTP, a built-in TOR tunnel and AES-256-encrypted build downloads. Not all of these are mentioned in the developers’ online ’sales’ material, suggesting continuous development.
Its stealth is verified by BlackFog. “Both delivery archives came back clean on their first VirusTotal upload, and the malicious component inside them was still unflagged when we last checked on May 30, 2026.” The build downloads are encrypted with AES256.
Within the build is a legitimate application with a valid Authenticate signature. On VirusTotal, this shows zero detections across 71 engines. It is paired with a DLL that is disguised as an NVIDIA graphics library, but with the payload appended at the end following legitimate content. When the victim runs install for the application, it loads the malicious DLL simultaneously. The payload remains encrypted until runtime – effectively when the stealer is loaded and starts its harvesting.
A stealer with this reach turns one compromised workstation into standing access across a person’s working life. The combination of its stealth and persistence helps ensure that the standing access exists for an extended period.
Overall, the very existence of OnyxC2, more like a commercial if malicious software product, amply demonstrates that the stealer threat is not going away. Rather, it is growing in sophistication and threat.
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