CVE-2018-19463 in Z-BlogPHP
Summary
by MITRE
zb_system/function/lib/upload.php in Z-BlogPHP through 1.5.1 allows remote attackers to execute arbitrary PHP code by using the image/jpeg content type in an upload to the zb_system/admin/index.php?act=UploadMng URI.
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Analysis
by VulDB Data Team • 08/05/2024
The vulnerability identified as CVE-2018-19463 represents a critical remote code execution flaw within Z-BlogPHP versions 1.5.1 and earlier. This vulnerability exists in the upload functionality of the system's administrative interface, specifically within the zb_system/function/lib/upload.php file. The flaw allows malicious actors to bypass normal file upload restrictions by manipulating the content type header during file uploads, specifically exploiting the image/jpeg MIME type to execute arbitrary PHP code on the target server.
The technical implementation of this vulnerability stems from insufficient input validation and content type checking within the file upload mechanism. When an attacker submits a file through the zb_system/admin/index.php?act=UploadMng endpoint, the system fails to properly verify the actual file content against its declared MIME type. This weakness enables attackers to upload malicious PHP files that are disguised as legitimate image files, exploiting the trust placed in the image/jpeg content type to execute code with the privileges of the web server process. The vulnerability directly maps to CWE-434, which describes the weakness of allowing untrusted data to be uploaded and executed as code, and aligns with ATT&CK technique T1190 for exploiting vulnerabilities in web applications.
The operational impact of this vulnerability is severe and multifaceted. Successful exploitation allows attackers to execute arbitrary commands on the affected server, potentially leading to complete system compromise, data exfiltration, and persistence mechanisms. Attackers can leverage this vulnerability to establish backdoors, deploy additional malware, or use the compromised server as a launch point for further attacks within the network. The vulnerability affects the administrative interface of Z-BlogPHP, making it particularly dangerous as it provides attackers with access to sensitive administrative functions and potentially full control over the blog's content management system. The attack requires minimal privileges to exploit, as the vulnerability exists within the web application's upload functionality that is accessible to authenticated users with appropriate permissions.
Mitigation strategies for CVE-2018-19463 should focus on immediate patching of the affected Z-BlogPHP versions to 1.5.2 or later, where the vulnerability has been addressed through improved file validation and content type checking mechanisms. Organizations should implement additional security measures including strict file type validation that examines actual file signatures rather than relying solely on MIME type headers, implementing proper file extension filtering, and restricting upload directories to prevent execution of uploaded files. Network-level protections such as web application firewalls should be configured to monitor and block suspicious upload patterns, while regular security audits should verify that file upload mechanisms properly validate both file content and metadata. The vulnerability demonstrates the importance of following secure coding practices as outlined in OWASP Top Ten and NIST cybersecurity guidelines, particularly regarding input validation and file handling security controls.