Windows CLFS and five exploits used by ransomware operators (Exploit #1 – CVE-2022-24521)

This report analyzes CVE-2022-24521 and a CLFS-based exploitation method where crafted BLF files overwrite client and container structures to make a kernel pointer equal to a controlled value, enabling an arbitrary QWORD decrement via CClfsContainer::Close and the well-known PreviousMode technique to escalate privileges; it documents active use in ransomware campaigns, sale of a 1‑day exploit on dark forums, and the attack chain including NtQuerySystemInformation, allocation at 0x40000000, and token replacement to achieve SYSTEM.