NailaoLoader DLL Sideloading via usysdiag.exe Loading sensapi.dll (via image_load)

ATT&CK techniques

Execution → Defense Evasion

Recon
Resource Dev
Initial Access
Execution
- T1574.001DLL
Persistence
- T1574.001DLL
Priv Esc
- T1574.001DLL
Defense Evasion
- T1574.001DLL
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule detects the signed Huorong binary usysdiag.exe loading a sensapi.dll from outside the Windows system directories, the DLL side-loading behavior used to launch NailaoLoader and decrypt the NailaoLocker ransomware in intrusions following CVE-2024-24919 exploitation of Check Point gateways. Adversaries abuse a trusted signed binary to run the loader under a legitimate process while evading detection.

Reporting behind it

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NailaoLoader DLL Sideloading via usysdiag.exe Loading sensapi.dll (via image_load)

Pivot detection · T1574.001 · 9 related

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

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