The nebula-sdk npm package (versions 1.0.0 and 1.0.1) includes a preinstall.cjs lifecycle script that embeds a base64-encoded, zlib-compressed Windows PE executable (~257KB). Upon npm install, this script decodes and decompresses the payload, writes it as conhost.exe under %LOCALAPPDATA%\Microsoft\Conhost\, and executes it detached with hidden windows and no stdio, effectively running attacker-controlled native code on the Windows host without user interaction. The payload references a known RAT tool repository and an IP address associated with malicious activity. The package's advertised AI SDK functionality is unrelated to this hidden malicious payload, which is delivered through multi-layer obfuscation.

Any Windows system that installs nebula-sdk versions 1.0.0 or 1.0.1 is fully compromised, as the malicious payload executes native code with no user interaction. This can lead to complete attacker control over the system, including access to secrets and keys stored on the machine. Removal of the package does not guarantee removal of all malicious components or persistence mechanisms installed by the payload.

Immediate removal of the nebula-sdk package versions 1.0.0 and 1.0.1 is recommended. All secrets, credentials, and keys stored on the affected machine should be considered compromised and rotated from a separate, trusted system. Due to the nature of the compromise, a full system reinstallation or forensic analysis is advised to ensure complete eradication of the malicious payload and any persistence mechanisms. No official patch or fix is available; users must avoid installing these versions.