CVE-2018-10085 in CMS Made Simple
Summary
by MITRE
CMS Made Simple (CMSMS) through 2.2.6 allows PHP object injection because of an unserialize call in the _get_data function of \lib\classes\internal\class.LoginOperations.php. By sending a crafted cookie, a remote attacker can upload and execute code, or delete files.
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Analysis
by VulDB Data Team • 01/24/2020
The vulnerability identified as CVE-2018-10085 affects CMS Made Simple versions 2.2.6 and earlier, representing a critical security flaw that stems from improper input validation and unsafe deserialization practices. This vulnerability exists within the _get_data function located in the \lib directory of the CMSMS application, where an unserialize call processes user-supplied data without adequate sanitization or validation. The flaw enables attackers to inject malicious PHP objects during the deserialization process, potentially leading to arbitrary code execution on the affected server. This type of vulnerability falls under the category of CWE-502, which specifically addresses deserialization of untrusted data, making it particularly dangerous in web applications where user input is frequently processed.
The technical implementation of this vulnerability exploits the inherent risks associated with PHP's unserialize function when handling untrusted input streams. When CMSMS processes data through the _get_data function, it accepts serialized PHP objects from external sources and directly passes them to unserialize without proper validation or sanitization. This creates an attack surface where malicious actors can craft specially crafted serialized objects that, when deserialized, execute arbitrary PHP code on the server. The vulnerability demonstrates a classic lack of input sanitization and proper data validation mechanisms, which are fundamental security controls recommended by the OWASP Top Ten and other industry security frameworks. Attackers can leverage this flaw to execute commands, access sensitive data, or potentially gain full control over the affected web server.
The operational impact of CVE-2018-10085 extends beyond simple code execution, as it fundamentally compromises the integrity and confidentiality of the affected CMSMS installations. Successful exploitation can lead to complete system compromise, data breaches, and potential lateral movement within network environments where the vulnerable CMS is deployed. Organizations running CMSMS versions prior to 2.2.7 face significant risk exposure, particularly if the application is hosted on publicly accessible servers or if the CMS is used to manage sensitive information. The vulnerability is particularly concerning because it does not require authentication to exploit, making it accessible to any attacker who can submit data to the affected application. This characteristic aligns with ATT&CK technique T1203, which involves gaining access through exploitation of software vulnerabilities, and represents a critical weakness in the application's defense-in-depth strategy.
Mitigation strategies for CVE-2018-10085 primarily focus on immediate remediation through version updates, as the vulnerability was addressed in CMSMS version 2.2.7. Organizations should prioritize upgrading their CMSMS installations to the patched version to eliminate the risk of exploitation. Additionally, implementing proper input validation and sanitization measures can provide defense-in-depth protection, though this approach is less reliable than the official patch. Security measures should include monitoring for suspicious activity related to the affected _get_data function, implementing web application firewalls to detect and block malicious serialized data, and conducting comprehensive vulnerability assessments of all CMSMS installations. The vulnerability also underscores the importance of following secure coding practices such as avoiding direct unserialize calls on user-supplied data, implementing proper data validation, and utilizing safer alternatives like JSON serialization where possible. Organizations should also consider implementing network segmentation and access controls to limit the potential impact of successful exploitation, as recommended by NIST SP 800-53 security controls for application security.