CVE-2017-5543 in Subrion CMS
Summary
by MITRE
includes/classes/ia.core.users.php in Subrion CMS 4.0.5 allows remote attackers to conduct PHP Object Injection attacks via crafted serialized data in a salt cookie in a login request.
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Analysis
by VulDB Data Team • 05/14/2026
The vulnerability identified as CVE-2017-5543 represents a critical PHP Object Injection flaw within the Subrion CMS 4.0.5 framework, specifically affecting the ia.core.users.php file. This vulnerability resides in the authentication handling mechanism where the application fails to properly validate and sanitize serialized data received through the salt cookie parameter during login requests. The flaw enables remote attackers to inject malicious PHP objects that can be unserialized and executed within the application context, potentially leading to complete system compromise. The vulnerability is classified under CWE-502 as deserialization of untrusted data, which is a well-documented attack vector that has been exploited in numerous high-profile security incidents across various web applications.
The technical exploitation of this vulnerability occurs when an attacker crafts malicious serialized PHP objects and places them within the salt cookie value during authentication attempts. When the Subrion CMS processes this cookie data, it attempts to unserialize the serialized object without proper input validation or sanitization. This unserialization process triggers the execution of malicious code within the application's context, potentially allowing attackers to perform arbitrary code execution, escalate privileges, or gain unauthorized access to sensitive system resources. The attack vector is particularly dangerous because it operates entirely within the HTTP communication layer and does not require any prior authentication or privileged access to the system.
The operational impact of CVE-2017-5543 extends beyond simple code execution, as it can enable attackers to establish persistent access to the affected system and potentially compromise the entire web infrastructure. Successful exploitation can result in data theft, system takeover, and the deployment of backdoors or additional malware. The vulnerability affects the core authentication mechanism of the CMS, making it a prime target for attackers seeking to gain unauthorized access to user accounts and administrative privileges. This type of vulnerability aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter, where attackers can leverage the deserialization flaw to execute arbitrary commands through PHP object injection. Organizations running Subrion CMS 4.0.5 are at significant risk of being compromised, especially if they do not implement proper input validation or use outdated versions of the software.
Mitigation strategies for this vulnerability should focus on immediate patching of the affected Subrion CMS version to the latest available release that addresses the deserialization flaw. System administrators should implement strict input validation and sanitization for all cookie data, particularly in authentication-related components. The implementation of Content Security Policy headers and disabling unnecessary PHP functions can further reduce the attack surface. Additionally, organizations should consider implementing web application firewalls to detect and block malicious serialized data attempts. Regular security assessments and vulnerability scanning should be conducted to identify similar flaws in other components of the web application stack, as this vulnerability demonstrates the importance of proper object serialization handling and input validation in web applications. The remediation process should also include monitoring for any signs of exploitation attempts and implementing proper logging mechanisms to track authentication-related activities and cookie modifications.