MAL-2026-11499 Malicious code in @types-beta/sdk (npm)

The npm package @types-beta/sdk is a supply-chain dropper that impersonates the trusted @types (DefinitelyTyped) namespace to look like a routine type-definition dependency. It bundles a Windows executable (vendor/nanocache.exe) and launches it as an import-time side effect: dist/index.js calls init() at module load, and on Windows init() spawns the bundled binary via child_process — detached, stdio: 'ignore', windowsHide: true. There is no lifecycle install hook; simply importing the package (directly or transitively) executes the payload on Windows.

Static analysis of the bundled binary (it was not executed) shows a WinHTTP WebSocket-based remote-access agent: it dials out to a command-and-control server and maintains a persistent, auto-reconnecting channel (WinHttpConnect / WinHttpWebSocketSend / WinHttpWebSocketReceive), executes remote commands, and starts an interactive PowerShell session. Embedded strings include [agent] Connecting to %ls:%d (secure=%d), [+] Connected client=%s server=%ls, [>] cmd: %s, and [shell] PowerShell session started (UTF-8, pipeline mode), with [-] Disconnected, reconnecting in %dms... for resilience.

Versions 0.1.0-0.1.3 are affected and were live on npm at the time of reporting.

The package masquerades as a type-definitions package in the @types-beta/* namespace but ships a 1.1 MB Windows executable at vendor/nanocache.exe. The main entry dist/index.js calls init() at module load time, which on Windows spawns vendor/nanocache.exe with detached: true, stdio: "ignore", windowsHide: true, then child.unref()s it, so a hidden background process starts whenever a consumer writes import "@types-beta/sdk". The bundled PE (sha256 9a65f46787db4dd1e278a06f617094c59ca113ee92f6a8021b62967bb64b947a) contains embedded strings consistent with a remote-control agent (/ws/agent, disconnect, update, exit_code). The README reinforces the impersonation by contrasting the package with @types-beta/node as "type definitions only", while this package auto-executes native code on import. Import-time launch of an opaque, undocumented native binary with agent-shaped protocol strings on a namespace crafted to imitate DefinitelyTyped constitutes a backdoor installation on the developer's host.