What HYFLOCK Does
HYFLOCK is a ransomware variant discovered on VirusTotal that encrypts files on Windows systems and appends the “.locked” extension. A file named “report.docx” becomes “report.docx.locked”. After encryption completes, it drops an HTML ransom note instructing victims to install qTox and Tor Browser to contact the attackers within 48 hours.
The ransom note warns victims not to attempt recovery, not to modify encrypted files, not to use third-party tools, and not to reboot. The implication is clear: pay or lose your data permanently.
Like most ransomware, HYFLOCK uses strong encryption — in this case HC-128 — that cannot be broken without the attacker’s key. Paying the ransom is no guarantee of recovery. Scumbags routinely take payment and disappear.
The article correctly advises against paying and recommends removing the malware and restoring from backup. But most organizations don’t have current backups of everything. And removal doesn’t decrypt files that are already locked.
Why Traditional Security Missed It
Antivirus software works by recognizing threats it has already seen. A researcher finds HYFLOCK, analyzes it, creates a signature, and pushes an update. Your antivirus learns to block it.
That process takes time. The window between a new ransomware release and when your antivirus can detect it can be hours or days. That’s exactly when attacks happen.
HYFLOCK appeared on VirusTotal, which means researchers submitted it for analysis. But every organization that encountered HYFLOCK before that signature existed had no protection. The malware walked right past their antivirus because it wasn’t on the list yet.
This isn’t a failure of antivirus vendors. It’s a fundamental limitation of signature-based detection. You can’t block what you don’t recognize.
How FileSure Blocks It at the File System Level
FileSure Defend doesn’t try to recognize ransomware. It operates at the Windows kernel level via a filter driver that intercepts file system operations before they complete.
Ransomware has to write encrypted versions of your files to disk. There’s no way around that. HYFLOCK reads “report.docx”, encrypts the contents in memory, writes the encrypted data back to disk, and renames the file to “report.docx.locked”. Those are file system operations: read, write, rename.
FileSure intercepts those operations and enforces your policy. Two mechanisms apply here:
First: block the payload from landing. Most ransomware arrives via email attachment or malicious download. The delivery program (Outlook, Chrome, Firefox) writes the executable payload to disk. FileSure can block any program from writing executable file types (.exe, .dll, .vbs, .wsh) to the hard drive. The payload never lands. The ransomware never runs.
Second: detect and block bulk encryption. If the ransomware somehow executes — maybe it was already on the system, or it arrived through a method you didn’t block — FileSure’s threshold rule detects the encryption pattern. Configure it like this:
- File name filter:
*(all files) - Operations: Write, Rename/Move
- Drive type: Hard drives, Network drives, Removable drives
- Threshold: 20 matches within 60 minutes
- Action: Block
A normal user saving Word documents or editing spreadsheets won’t hit 20 file modifications in an hour. Ransomware encrypting hundreds of files crosses that threshold in seconds. FileSure blocks all subsequent write and rename operations. The attack stops at file 20, not file 5,000.
No signature required. No update needed. It works on HYFLOCK, and it works on the ransomware variant that gets released tomorrow that nobody has seen yet.
This Works on Legacy Systems Too
The article notes that HYFLOCK provides installation instructions for Windows, Linux, and macOS. FileSure runs exclusively on Windows — but it runs on every Windows version from Server 2003 through Server 2022.
If you have medical equipment, industrial control systems, or specialized software locked to an older Windows version — the kind of system that modern endpoint security tools won’t even install on — FileSure protects those too. Ransomware doesn’t care how old your OS is. Neither does FileSure.
FileSure Defend stops ransomware by controlling file system operations at the kernel level. No signatures, no updates, no waiting for someone else to catch up. Start your free 21-day trial at bystorm.com — 1 server, 10 workstations, fully functional.
Source: HYFLOCK Ransomware – Decryption, removal, and lost files recovery
Category: Ransomware
Tags: hyflock ransomware, file encryption, kernel filter driver, ransomware prevention, file system security, threshold detection, windows security
