CVE-2020-24771
📋 TL;DR
CVE-2020-24771 is an incorrect access control vulnerability in NexusPHP that allows unauthorized attackers to access published content without proper authentication. This affects NexusPHP 1.5.beta5.20120707 installations where content should be restricted to authorized users only.
💻 Affected Systems
- NexusPHP
📦 What is this software?
Nexusphp by Nexusphp
⚠️ Risk & Real-World Impact
Worst Case
Unauthorized access to sensitive published content, potentially including private user data, proprietary information, or restricted resources.
Likely Case
Unauthorized viewing of content that should be protected, leading to information disclosure and potential privacy violations.
If Mitigated
Proper access controls prevent unauthorized access, maintaining content confidentiality and user privacy.
🎯 Exploit Status
The vulnerability allows unauthenticated access to content, making exploitation straightforward with available proof-of-concept code.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.6.0-beta2 and later
Vendor Advisory: https://nexusphp.org/2021/02/03/nexusphp-v1-6-0-beta2/
Restart Required: No
Instructions:
1. Backup your current NexusPHP installation. 2. Download and install NexusPHP version 1.6.0-beta2 or later. 3. Replace affected files with patched versions. 4. Test functionality to ensure proper access controls are working.
🔧 Temporary Workarounds
Implement additional access control middleware
allAdd custom authentication checks before serving any published content
# Add authentication check in PHP before content delivery
if (!isset($_SESSION['authenticated']) || $_SESSION['authenticated'] !== true) {
header('HTTP/1.0 403 Forbidden');
exit('Access denied');
}
🧯 If You Can't Patch
- Implement web application firewall (WAF) rules to block unauthorized access attempts
- Restrict network access to the NexusPHP application using firewall rules
🔍 How to Verify
Check if Vulnerable:
Attempt to access published content without authentication. If accessible, the system is vulnerable.Check Version:
Check the version.php file or admin panel for NexusPHP version informationVerify Fix Applied:
Test accessing published content without authentication - should receive access denied error.📡 Detection & Monitoring
Log Indicators:
- Multiple 200 OK responses for content access without corresponding authentication logs
- Access to restricted content paths from unauthenticated IP addresses
Network Indicators:
- HTTP requests to content endpoints without authentication headers or cookies
SIEM Query:
source="web_access.log" (status=200) AND NOT (user="authenticated" OR cookie="session_id") AND uri CONTAINS "/content/"🔗 References
- https://cwe.mitre.org/data/definitions/306.html
- https://github.com/burpheart/CVE/blob/master/2020-08-13-03.md
- https://nexusphp.org/2021/02/03/nexusphp-v1-6-0-beta2/
- https://cwe.mitre.org/data/definitions/306.html
- https://github.com/burpheart/CVE/blob/master/2020-08-13-03.md
- https://nexusphp.org/2021/02/03/nexusphp-v1-6-0-beta2/
