CVE-2024-34009
📋 TL;DR
This vulnerability allows attackers to bypass ReCAPTCHA protection on the login page of affected systems, potentially enabling brute-force attacks or unauthorized access attempts. It specifically affects Moodle installations where ReCAPTCHA is configured but insufficient validation occurs. Organizations using vulnerable Moodle versions with ReCAPTCHA enabled are affected.
💻 Affected Systems
- Moodle
📦 What is this software?
Moodle by Moodle
⚠️ Risk & Real-World Impact
Worst Case
Attackers could perform unlimited automated login attempts, potentially compromising user accounts through credential stuffing or brute-force attacks, leading to unauthorized access to sensitive educational data.
Likely Case
Increased risk of account takeover attempts through automated login attempts, potentially disrupting legitimate user access and increasing administrative overhead for account recovery.
If Mitigated
With proper monitoring and additional authentication controls, impact is limited to increased login attempts that can be detected and blocked before successful compromise.
🎯 Exploit Status
The vulnerability appears to be a logic flaw that could be exploited with simple HTTP request manipulation. No authentication required to attempt exploitation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not specified in provided references, but Moodle security updates typically address such issues
Vendor Advisory: https://moodle.org/mod/forum/discuss.php?d=458398
Restart Required: No
Instructions:
1. Check Moodle version. 2. Apply latest security update from Moodle. 3. Verify ReCAPTCHA functionality on login page. 4. Test login attempts with and without valid ReCAPTCHA responses.
🔧 Temporary Workarounds
Disable ReCAPTCHA on Login
allTemporarily disable ReCAPTCHA protection on login pages until patch is applied
Navigate to Site administration > Plugins > Authentication > Manage authentication > Edit settings for ReCAPTCHA
Implement Rate Limiting
allAdd additional rate limiting on login attempts at web server or application level
Configure rate limiting in web server (e.g., nginx: limit_req_zone) or use Moodle login attempt tracking
🧯 If You Can't Patch
- Implement additional authentication factors (MFA) for all user accounts
- Deploy WAF rules to detect and block suspicious login patterns
🔍 How to Verify
Check if Vulnerable:
Test login page with invalid or missing ReCAPTCHA response - if login attempts proceed without proper validation, system is vulnerableCheck Version:
Check Moodle version via admin interface or config.php fileVerify Fix Applied:
After patching, verify that login attempts without valid ReCAPTCHA are properly rejected📡 Detection & Monitoring
Log Indicators:
- Multiple failed login attempts from same IP without ReCAPTCHA validation
- Login attempts with missing or invalid ReCAPTCHA parameters
Network Indicators:
- Unusual volume of POST requests to login endpoint
- Lack of ReCAPTCHA parameter in login requests
SIEM Query:
source="moodle_logs" AND (event="login_failed" AND NOT reCAPTCHA="valid") | stats count by src_ip