Detect CVE-2024-43451: Windows NTLM Hash Disclosure via File Interaction in Elastic Security
CVE-2024-43451 is a Windows NTLM hash disclosure vulnerability (NTLMv2 spoofing) affecting Windows 10, Windows 11, and Windows Server 2008-2025. Minimal user interaction with a malicious file (right-click, open, or preview) triggers an outbound NTLM authentication request to an attacker-controlled server, leaking the victim's NTLMv2 hash. The hash can be cracked offline or used in relay attacks. This vulnerability is listed in CISA's Known Exploited Vulnerabilities catalog.
MITRE ATT&CK
Elastic Detection Query
sequence by host.id with maxspan=30s
[file where event.action in ("open", "creation", "access") and
file.extension in ("url", "lnk", "scf", "library-ms", "searchConnector-ms") and
not file.path like~ "C:\\Windows\\*"]
[network where event.action == "connection_attempted" and
destination.port in (445, 139) and
not cidr_match(destination.ip, "10.0.0.0/8", "172.16.0.0/12", "192.168.0.0/16", "127.0.0.0/8", "::1/128")]EQL sequence rule correlating suspicious file access (.url, .lnk, .scf, etc.) with a subsequent outbound SMB connection to a non-RFC1918 IP within 30 seconds on the same host, the behavioral signature of CVE-2024-43451 exploitation.
Data Sources
Required Tables
False Positives & Tuning
- Legitimate internet-facing file servers accessed via mapped drives using shortcut files
- Antivirus or EDR solutions scanning shortcut files and triggering network lookups
- Browser downloads of .url files immediately followed by SMB beacon to referrer host
- IT asset management tools enumerating LNK files alongside network discovery probes
Other platforms for CVE-2024-43451
Testing Methodology
Validate this detection against 3 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1NTLM Hash Disclosure via Malicious .url File
Expected signal: Sysmon EventID 11 (file creation for .url file), Sysmon EventID 3 (network connection from explorer.exe to ATTACKER_IP:445), Windows Security EventID 4648 (explicit credential use targeting ATTACKER_IP), Responder captures NTLMv2 hash
- Test 2NTLM Hash Disclosure via Malicious .lnk Shortcut
Expected signal: Sysmon EventID 11 (LNK creation), Sysmon EventID 3 (explorer.exe → ATTACKER_IP:445), Windows Security EventID 4648 with LogonType=3 and TargetServerName=ATTACKER_IP
- Test 3NTLM Hash Disclosure via Malicious .scf (Shell Command File)
Expected signal: Sysmon EventID 3 from explorer.exe to ATTACKER_IP:445 without any explicit user action beyond folder view, Windows Security EventID 4648 capturing NTLMv2 exchange, network PCAP showing full NTLM handshake
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