CVE-2015-8838 in PHP
Summary
by MITRE
ext/mysqlnd/mysqlnd.c in PHP before 5.4.43, 5.5.x before 5.5.27, and 5.6.x before 5.6.11 uses the --ssl option to mean that SSL is optional, which allows man-in-the-middle attackers to spoof servers via a cleartext-downgrade attack, a related issue to CVE-2015-3152.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 08/19/2022
The vulnerability identified as CVE-2015-8838 resides within the mysqlnd extension of PHP, specifically in the mysqlnd.c file, affecting versions prior to 5.4.43, 5.5.x before 5.5.27, and 5.6.x before 5.6.11. This flaw represents a significant security weakness in how PHP handles SSL connections to MySQL databases, creating a dangerous misconfiguration that undermines the intended security posture of encrypted communications. The issue stems from the improper interpretation of the --ssl command-line option which PHP's mysqlnd extension uses, where the option is interpreted to mean SSL is optional rather than mandatory, creating a fundamental gap in connection security.
The technical flaw manifests when PHP applications establish database connections using the mysqlnd extension and specify the --ssl option. Instead of enforcing SSL encryption for all connections, the implementation treats SSL as a negotiable feature that can be bypassed, allowing attackers to perform man-in-the-middle attacks by downgrading connections from encrypted to cleartext. This creates a scenario where an attacker positioned between the PHP application and MySQL server can intercept and manipulate communication without detection. The vulnerability operates under the principle that the --ssl flag should enforce secure connections but instead enables a fallback mechanism that accepts cleartext communication when SSL cannot be established, effectively disabling the security benefits of SSL/TLS encryption.
From an operational impact perspective, this vulnerability exposes PHP applications to significant risks including data theft, unauthorized access to database contents, and potential system compromise through the interception of authentication credentials and sensitive information. The attack vector is particularly dangerous because it leverages the trust relationship between applications and databases, allowing attackers to perform credential harvesting and data manipulation without requiring elevated privileges or complex attack vectors. The vulnerability directly relates to CWE-310, which addresses cryptographic weaknesses, specifically focusing on improper use of encryption and the failure to enforce mandatory security controls. This weakness creates a persistent risk for any application using affected PHP versions that connect to MySQL databases, particularly in environments where network traffic may be intercepted or where attackers have access to network monitoring capabilities.
The security implications extend beyond simple data interception to encompass broader system compromise scenarios, as attackers can exploit this weakness to perform credential theft, data exfiltration, and potentially escalate privileges within the database environment. Organizations running PHP applications that utilize MySQL connections are particularly vulnerable, especially those operating in environments where network security is not fully trusted or where legacy applications have not been updated to address this vulnerability. The attack pattern aligns with ATT&CK technique T1071.004, which involves application layer protocol manipulation, specifically targeting database communication protocols to undermine encryption. This vulnerability represents a critical weakness in the application security posture and requires immediate remediation through PHP version updates, along with proper configuration management to enforce mandatory SSL connections for database communications.
The recommended mitigations include immediate upgrade of PHP installations to versions that address this vulnerability, specifically ensuring PHP 5.4.43, 5.5.27, or 5.6.11 and later versions are deployed. Additionally, administrators should implement explicit SSL enforcement in database connection parameters, ensuring that applications do not rely on the default behavior of the --ssl flag. Network-level security measures should include monitoring for cleartext database connections and implementing proper firewall rules to enforce encrypted communication between application servers and database systems. Security configuration reviews should verify that database connection strings explicitly require SSL encryption rather than depending on optional SSL parameters, and that proper certificate validation is enforced to prevent certificate spoofing attacks that could exploit this vulnerability.