CVE-2020-5616
📋 TL;DR
CVE-2020-5616 is an authentication bypass vulnerability in multiple PHP-Factory free edition web applications that allows remote attackers to gain administrative privileges without valid credentials. This affects eight different applications including calendar, news, gallery, and voting systems. Organizations using these vulnerable PHP applications are at risk of complete system compromise.
💻 Affected Systems
- Calendar01
- Calendar02
- PKOBO-News01
- PKOBO-vote01
- Telop01
- Gallery01
- CalendarForm01
- Link01
📦 What is this software?
Calendar01 by Calendar01 Project
Calendar02 by Calendar02 Project
Calendarform01 by Calendarform01 Project
Gallery01 by Gallery01 Project
Link01 by Link01 Project
Pkobo News01 by Pkobo News01 Project
Pkobo Vote01 by Pkobo Vote01 Project
Telop01 by Telop01 Project
⚠️ Risk & Real-World Impact
Worst Case
Attackers gain full administrative control over affected applications, allowing data theft, defacement, malware deployment, and use as attack platforms.
Likely Case
Unauthorized administrative access leading to data manipulation, content modification, and potential lateral movement within the network.
If Mitigated
Limited impact if applications are isolated, monitored, and have additional authentication layers, though risk remains significant.
🎯 Exploit Status
Authentication bypass via unspecified vectors suggests simple exploitation. CVSS 9.8 indicates trivial exploitation with high impact.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Update to latest versions beyond affected ranges
Vendor Advisory: https://jvn.jp/en/jp/JVN73169744/index.html
Restart Required: Yes
Instructions:
1. Download latest versions from PHP-Factory website. 2. Backup current installation. 3. Replace files with updated versions. 4. Restart web server. 5. Verify authentication works correctly.
🔧 Temporary Workarounds
Network Access Restriction
allRestrict access to affected applications using firewall rules or web server configuration
# Apache: Require ip 192.168.1.0/24
# Nginx: allow 192.168.1.0/24; deny all;
# iptables: iptables -A INPUT -p tcp --dport 80 -s 192.168.1.0/24 -j ACCEPT
Web Application Firewall
allDeploy WAF rules to detect and block authentication bypass attempts
# ModSecurity rule example: SecRule REQUEST_URI "@rx admin" "id:1001,phase:2,deny"
🧯 If You Can't Patch
- Isolate affected applications in separate network segments with strict access controls
- Implement additional authentication layer (e.g., HTTP basic auth, IP whitelisting) before application login
🔍 How to Verify
Check if Vulnerable:
Check application version against affected list. Attempt to access admin functions without proper credentials.Check Version:
Check version in application files or admin panel. For PHP files: grep -r 'version' *.phpVerify Fix Applied:
Test authentication by attempting to bypass login. Verify only authorized users can access administrative functions.📡 Detection & Monitoring
Log Indicators:
- Multiple failed login attempts followed by successful admin access from same IP
- Admin panel access from unusual IP addresses
- Authentication bypass patterns in access logs
Network Indicators:
- HTTP requests to admin URLs without preceding login requests
- Unusual traffic patterns to application administrative endpoints
SIEM Query:
source="web.log" (url="*admin*" OR url="*login*") AND (response_code=200) NOT (user="authenticated_user")🔗 References
- https://jvn.jp/en/jp/JVN73169744/index.html
- https://www.php-factory.net/calendar/01.php
- https://www.php-factory.net/calendar/02.php
- https://www.php-factory.net/calendar_form/01.php
- https://www.php-factory.net/gallery/01.php
- https://www.php-factory.net/link/01.php
- https://www.php-factory.net/news/pkobo-news01.php
- https://www.php-factory.net/telop/01.php
- https://www.php-factory.net/vote/01.php
- https://jvn.jp/en/jp/JVN73169744/index.html
- https://www.php-factory.net/calendar/01.php
- https://www.php-factory.net/calendar/02.php
- https://www.php-factory.net/calendar_form/01.php
- https://www.php-factory.net/gallery/01.php
- https://www.php-factory.net/link/01.php
- https://www.php-factory.net/news/pkobo-news01.php
- https://www.php-factory.net/telop/01.php
- https://www.php-factory.net/vote/01.php
