CVE-2020-14932
📋 TL;DR
CVE-2020-14932 is a critical PHP object injection vulnerability in SquirrelMail's compose.php that allows remote code execution by deserializing untrusted data from HTTP GET requests. This affects all SquirrelMail installations with the vulnerable code path accessible. Attackers can exploit this without authentication to compromise the web server.
💻 Affected Systems
- SquirrelMail
📦 What is this software?
Squirrelmail by Squirrelmail
⚠️ Risk & Real-World Impact
Worst Case
Full server compromise leading to data theft, lateral movement, and persistent backdoor installation
Likely Case
Remote code execution with web server privileges, allowing file system access and further exploitation
If Mitigated
Blocked exploitation attempts with proper input validation and WAF rules in place
🎯 Exploit Status
Exploit code is publicly available and trivial to execute
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.4.23 and later
Vendor Advisory: https://www.openwall.com/lists/oss-security/2020/06/20/1
Restart Required: No
Instructions:
1. Download SquirrelMail 1.4.23 or later from official repository. 2. Backup current installation. 3. Replace compose.php and mailto.php with patched versions. 4. Verify functionality.
🔧 Temporary Workarounds
Disable mailto.php functionality
linuxRemove or restrict access to mailto.php to prevent exploitation vector
mv /path/to/squirrelmail/mailto.php /path/to/squirrelmail/mailto.php.disabled
Input validation filter
allAdd input sanitization for GET parameters in compose.php
Add: if (isset($_GET['mailtodata'])) { $_GET['mailtodata'] = filter_var($_GET['mailtodata'], FILTER_SANITIZE_STRING); }
🧯 If You Can't Patch
- Implement strict WAF rules to block requests containing serialized PHP objects
- Restrict network access to SquirrelMail interface using firewall rules
🔍 How to Verify
Check if Vulnerable:
Check if compose.php contains unserialize() call on $_GET['mailtodata'] without proper validationCheck Version:
grep '\$version' /path/to/squirrelmail/functions/global.php | head -1Verify Fix Applied:
Verify compose.php no longer uses unserialize() on untrusted input or implements proper validation📡 Detection & Monitoring
Log Indicators:
- HTTP GET requests to compose.php with mailtodata parameter containing serialized data
- Unusual PHP process execution from web server context
Network Indicators:
- HTTP requests with serialized objects in URL parameters
- Unexpected outbound connections from web server
SIEM Query:
source="web_logs" AND url="*compose.php*" AND url="*mailtodata=*" AND (url="*O:*" OR url="*a:*" OR url="*s:*")