Microsoft fixes exploited zero-day (CVE-2024-49138)

Windows Resilient File System (ReFS) Elevation of Privilege Vulnerability

CVE-2024-49112 is an integer overflow (CWE-190) in the Windows Lightweight Directory Access Protocol (LDAP) implementation that permits remote code execution. It is triggered by network traffic sent to the LDAP service, with no authentication or user interaction required (CVSS 3.1 network vector, low complexity, no privileges). A successful attacker gains arbitrary code execution in the context of the LDAP service process on the target, and on Active Directory domain controllers this typically means compromising a core infrastructure host with high confidentiality, integrity, and availability impact. All listed Windows 10 and Windows 11 client versions and Windows Server 2008 through 2022 are affected, making virtually every unpatched Windows environment — especially those running domain controllers — exposed. Per related coverage, the flaw was addressed in Microsoft's December 2024 Patch Tuesday (72 flaws fixed, four rated critical); no public proof-of-concept or confirmed in-the-wild exploitation is known for this specific RCE yet, though a related Windows LDAP flaw ('LDAPNightmare') has a public PoC that crashes LSASS and reboots domain controllers, and the ~71% EPSS score signals a high likelihood of exploitation within 30 days.

Do: Apply Microsoft's December 2024 (or later) Windows security updates immediately, prioritizing domain controllers and any server with LDAP reachable from untrusted networks. Until fully patched, restrict inbound LDAP/LDAPS traffic (TCP and UDP 389 and 636) to trusted sources and monitor for LSASS crashes or restarts on domain controllers. Because fixes are version-specific cumulative updates, verify each Windows release against Microsoft's advisory to confirm the correct KB is installed.

Windows Cloud Files Mini Filter Driver Elevation of Privilege Vulnerability

Microsoft's Windows Common Log File System (CLFS) driver contains a heap-based buffer overflow (CWE-122) that a local attacker can trigger by submitting crafted input to the CLFS component after gaining the ability to run code on the target machine. Successful exploitation overwrites heap memory in the kernel driver and allows the attacker to escalate privileges, typically from an ordinary user account to SYSTEM-level execution. Any Microsoft Windows system is potentially affected; the CISA listing identifies only "Microsoft Windows" and does not enumerate specific versions or builds, and no CVSS score has been published yet. The flaw was added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2024-12-10, confirming it is being exploited in the wild (ransomware use is unknown), and EPSS assigns a 25.4% probability of exploitation activity within 30 days (98th percentile). No public proof-of-concept is known, but the in-the-wild exploitation means defenders should treat this as an actively used privilege-escalation primitive, often chained after initial access by malware or another exploit.

Do: Apply Microsoft's security update for Windows per vendor instructions, as required by the CISA KEV listing (added 2024-12-10), and verify patch compliance across Windows endpoints. Because this is a local privilege escalation, prioritize hosts where untrusted users or malware execute code, and review telemetry for local code execution followed by unexpected escalation to SYSTEM. No public PoC exists, so detection should rely on vendor advisory guidance and EDR telemetry rather than public exploit signatures.