CVE-2019-9061 in CMS Made Simple
Summary
by MITRE
An issue was discovered in CMS Made Simple 2.2.8. In the module ModuleManager (in the file action.installmodule.php), it is possible to reach an unserialize call with untrusted input and achieve authenticated object injection by using the "install module" feature.
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Analysis
by VulDB Data Team • 05/27/2020
The vulnerability identified as CVE-2019-9061 affects CMS Made Simple version 2.2.8 and represents a critical security flaw in the ModuleManager component. This issue stems from improper input validation within the action.installmodule.php file where user-supplied data flows directly into a unserialize() function call without adequate sanitization or verification. The vulnerability requires authenticated access but presents a severe risk as it allows attackers who have gained login credentials to execute arbitrary code on the affected system. This type of vulnerability falls under the category of deserialization attacks that can lead to remote code execution when untrusted data is processed through PHP's unserialize function.
The technical exploitation of this vulnerability occurs through the "install module" feature of the CMS, which provides a legitimate pathway for administrators to add new modules to their website. However, the flaw allows an attacker with valid credentials to manipulate the module installation process by injecting malicious serialized objects. When the system attempts to unserialize this crafted input, it executes arbitrary code as part of the deserialization process. This vulnerability is classified as CWE-502 under the Common Weakness Enumeration framework, specifically addressing "Deserialization of Untrusted Data" which is a well-known attack vector that has been exploited in numerous high-profile security incidents. The attack pattern aligns with techniques described in the MITRE ATT&CK framework under the T1059.007 sub-technique for "Command and Scripting Interpreter: PowerShell" and T1021.001 for "Remote Services: Remote Desktop Protocol" as attackers can leverage such vulnerabilities to establish persistent access and execute commands on the compromised system.
The operational impact of this vulnerability extends beyond simple code execution as it provides attackers with the capability to fully compromise the CMS server. Successful exploitation can result in complete system takeover, data exfiltration, and the potential for lateral movement within the network infrastructure. Organizations using CMS Made Simple 2.2.8 are particularly at risk since the vulnerability exists in the core module management functionality that is commonly used by administrators. The authenticated nature of the attack means that attackers must first obtain valid user credentials, but this is often achievable through various social engineering techniques, credential stuffing attacks, or exploitation of other vulnerabilities in the web application stack. The vulnerability also poses a significant risk to websites that host sensitive data or serve as critical business applications, as the compromise of such systems can lead to substantial financial and reputational damage. Organizations should prioritize immediate remediation through official patches provided by CMS Made Simple, implement network monitoring to detect suspicious installation activities, and ensure that administrative access is protected through strong authentication mechanisms including multi-factor authentication to mitigate the risk of exploitation.
The vulnerability demonstrates how seemingly legitimate administrative features can become attack vectors when proper input validation and sanitization are not implemented. The flaw represents a classic example of how object injection vulnerabilities can be leveraged to bypass traditional security controls, as the unserialize() function processes serialized data without sufficient verification of its source or integrity. Security practitioners should recognize this pattern as a common indicator of insecure deserialization practices and apply defensive measures such as input validation, output encoding, and implementing proper access controls to prevent similar vulnerabilities from being exploited in other applications. The incident underscores the importance of secure coding practices and the need for regular security assessments of web applications to identify and remediate such critical flaws before they can be exploited by malicious actors.