CVE-2019-7912 in Magento
Summary
by MITRE
A file upload filter bypass exists in Magento 2.1 prior to 2.1.18, Magento 2.2 prior to 2.2.9, Magento 2.3 prior to 2.3.2. This can be exploited by an authenticated user with admin privileges to edit configuration keys to remove file extension filters, potentially resulting in the malicious upload and execution of malicious files on the server.
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Analysis
by VulDB Data Team • 07/20/2020
The vulnerability identified as CVE-2019-7912 represents a critical file upload filter bypass in Magento e-commerce platforms that affects multiple versions including Magento 2.1 prior to 2.1.18, Magento 2.2 prior to 2.2.9, and Magento 2.3 prior to 2.3.2. This security flaw resides in the configuration management system where authenticated administrators can manipulate file upload restrictions through configuration key modifications. The vulnerability stems from insufficient validation mechanisms that allow malicious actors with administrative access to weaken or eliminate file extension filters, creating an avenue for arbitrary code execution on the affected servers. The flaw is particularly dangerous because it leverages legitimate administrative privileges to undermine the platform's security controls, making it difficult to detect and mitigate through standard security monitoring approaches.
The technical implementation of this vulnerability involves a configuration-based attack vector where an authenticated user with administrative rights can modify specific configuration keys that control file upload validation. This bypass occurs when the system fails to properly validate or sanitize configuration changes that affect file type restrictions, allowing attackers to remove or weaken the filters that typically prevent uploading potentially malicious file types such as php, aspx, or other executable scripts. The underlying issue manifests as a failure in input validation and configuration management controls, which can be categorized under CWE-20 - Improper Input Validation and CWE-22 - Improper Limitation of a Pathname to a Restricted Directory. The vulnerability specifically targets the Magento platform's file upload handling mechanism, where configuration settings that govern file extensions are not properly enforced or validated when modified through the administrative interface.
The operational impact of CVE-2019-7912 extends beyond simple unauthorized file uploads to encompass full system compromise capabilities for attackers who gain administrative access. Once an attacker successfully removes file upload restrictions, they can upload malicious files that execute arbitrary code on the server, potentially leading to complete system takeover, data exfiltration, or deployment of additional malware. This vulnerability aligns with ATT&CK technique T1190 - Exploit Public-Facing Application, where attackers leverage legitimate administrative access to exploit weaknesses in application configuration management. The attack chain typically begins with gaining administrative credentials through social engineering, credential compromise, or other initial access methods, followed by configuration manipulation to disable security controls, and concluding with malicious file upload and execution. Organizations running affected Magento versions face significant risk of data breaches, service disruption, and regulatory compliance violations.
Mitigation strategies for CVE-2019-7912 require immediate patching of affected Magento versions to the latest releases that contain the necessary security fixes. Organizations should also implement strict access controls and privilege management to minimize the risk of unauthorized administrative access, as the vulnerability requires administrative privileges to exploit effectively. Regular monitoring of configuration changes and implementing automated alerts for suspicious configuration modifications can help detect potential exploitation attempts. Network segmentation and application firewalls should be deployed to limit access to administrative interfaces and file upload endpoints. Security teams should conduct comprehensive vulnerability assessments and penetration testing to identify any potential exploitation attempts that may have already occurred. Additionally, implementing proper file upload validation at multiple layers including client-side, server-side, and database-level validation can provide defense-in-depth protection against similar vulnerabilities. The remediation process should include thorough testing of patched environments to ensure that the security fixes do not introduce regressions in platform functionality while maintaining the integrity of the file upload system.