@saltcorn/plugins-loader unsanitized plugin name leads to a remote code execution (RCE) vulnerability when creating plugins using git source

Summary

### Summary

When creating a new plugin using the `git` source, the user-controlled value `req.body.name` is used to build the plugin directory where the location will be cloned. The API used to execute the `git clone` command with the user-controlled data is `child_process.execSync`. Since the user-controlled data is not validated, a user with admin permission can add escaping characters and execute arbitrary commands, leading to a command injection vulnerability.

### Details

Relevant code from source (`req.body`) to sink (`child_process.execSync`).

- file: https://github.com/saltcorn/saltcorn/blob/v1.0.0-beta.13/packages/server/routes/plugins.js#L1400

```js router.post( "/", isAdmin, error_catcher(async (req, res) => { const plugin = new Plugin(req.body); // [1] [...] try { await load_plugins.loadAndSaveNewPlugin( // [3] plugin, schema === db.connectObj.default_schema || plugin.source === "github" ); [...] } }) ); ```

- file: https://github.com/saltcorn/saltcorn/blob/v1.0.0-beta.13/packages/saltcorn-data/models/plugin.ts#L44 ```js class Plugin { [...] constructor(o: PluginCfg | PluginPack | Plugin) { [...] this.name = o.name; // [2] [...] } ```

- file: https://github.com/saltcorn/saltcorn/blob/v1.0.0-beta.13/packages/server/load_plugins.js#L64-L65 ```js const loadAndSaveNewPlugin = async (plugin, force, noSignalOrDB) => { [...] const loader = new PluginInstaller(plugin); // [4] const res = await loader.install(force); // [7] [...] }; ```

- file: https://github.com/saltcorn/saltcorn/blob/v1.0.0-beta.13/packages/plugins-loader/plugin_installer.js#L41-L61 ```js class PluginInstaller { constructor(plugin, opts = {}) { [...] const tokens = plugin.source === "npm" ? plugin.location.split("/") : plugin.name.split("/"); // [5] [...] this.tempDir = join(this.tempRootFolder, "temp_install", ...tokens); // [6] [...] }

async install(force) { [...] if (await this.prepPluginsFolder(force, pckJSON)) { // [8] [...] }

async prepPluginsFolder(force, pckJSON) { [...] switch (this.plugin.source) { [...] case "git": if (force || !(await pathExists(this.pluginDir))) { await gitPullOrClone(this.plugin, this.tempDir); // [9] [...] } ```

- file: https://github.com/saltcorn/saltcorn/blob/v1.0.0-beta.13/packages/plugins-loader/download_utils.js#L112 ```js const gitPullOrClone = async (plugin, pluginDir) => { [...] if (fs.existsSync(pluginDir)) { execSync(`git ${setKey} -C ${pluginDir} pull`); } else { execSync(`git ${setKey} clone ${plugin.location} ${pluginDir}`); // [10] } [...] }; ```

### PoC

- check that the file will be created by the command `echo "hello">/tmp/HACKED` does not exists: ``` cat /tmp/HACKED cat: /tmp/HACKED: No such file or directory ``` - login with an admin account - visit `http://localhost:3000/plugins/new` - enter the following fields: - Name: `;echo "hello">/tmp/HACKED` - Source: `git` - other fields blank - click `Create` - you will get an error saying `ENOENT: no such file or directory, ....` but the command `touch /tmp/HACKED` will be executed - to verify: ``` cat /tmp/HACKED hello ```

### Impact

Remote code execution

### Recommended Mitigation

Sanitize the `pluginDir` value before passing to `execSync`. Alternatively, use `child_process. execFileSync` API (docs: https://nodejs.org/api/child_process.html#child_processexecfilesyncfile-args-options)