CVE-2015-6967 in Nibbleblog
Summary
by MITRE
Unrestricted file upload vulnerability in the My Image plugin in Nibbleblog before 4.0.5 allows remote administrators to execute arbitrary code by uploading a file with an executable extension, then accessing it via a direct request to the file in content/private/plugins/my_image/image.php.
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Analysis
by VulDB Data Team • 01/06/2025
The CVE-2015-6967 vulnerability represents a critical security flaw in the Nibbleblog platform's My Image plugin, specifically affecting versions prior to 4.0.5. This vulnerability stems from inadequate input validation and file upload restrictions within the plugin's functionality, creating a pathway for remote code execution that could be exploited by malicious actors. The vulnerability is particularly dangerous because it targets administrative users who have access to the plugin's upload functionality, allowing them to bypass normal security controls and potentially compromise the entire web application.
The technical implementation of this vulnerability involves a classic unrestricted file upload attack vector where the My Image plugin fails to properly validate file extensions and content types during the upload process. Attackers can upload malicious files with executable extensions such as .php, .asp, or .jsp, which are then stored in the web server's file system. The vulnerability specifically targets the content/private/plugins/my_image/image.php endpoint, which serves as the access point for these uploaded files. This allows attackers to execute arbitrary code on the target system by simply making a direct HTTP request to the uploaded file, bypassing traditional web application security measures.
The operational impact of CVE-2015-6967 extends beyond simple code execution, as it provides attackers with persistent access to the compromised system. Once an attacker successfully uploads a malicious file, they can maintain control over the web server, potentially using the compromised platform as a foothold for further attacks within the network. The vulnerability aligns with CWE-434, which describes unrestricted upload of executable code, and maps to attack techniques in the MITRE ATT&CK framework under T1190 for exploit public-facing application and T1059 for command and scripting interpreter. The attack chain typically involves initial compromise through administrative access, followed by file upload, and finally remote code execution, making this vulnerability particularly dangerous for web applications that store user-uploaded content.
Mitigation strategies for CVE-2015-6967 require immediate implementation of multiple security controls. Organizations should upgrade to Nibbleblog version 4.0.5 or later, which includes proper file validation and sanitization measures. Additionally, administrators should implement strict file type validation by checking both file extensions and MIME types, while also implementing proper file naming conventions that prevent execution of uploaded files in web-accessible directories. Network-level protections such as web application firewalls should be configured to block suspicious file upload patterns and monitor for attempts to access uploaded files through the image.php endpoint. The vulnerability demonstrates the importance of principle of least privilege, where administrative access should be strictly limited and monitored, aligning with security best practices outlined in NIST SP 800-53 and ISO 27001 standards for web application security.