CVE-2022-23626 in blog
Summary
by MITRE • 02/09/2022
m1k1o/blog is a lightweight self-hosted facebook-styled PHP blog. Errors from functions `imagecreatefrom*` and `image*` have not been checked properly. Although PHP issued warnings and the upload function returned `false`, the original file (that could contain a malicious payload) was kept on the disk. Users are advised to upgrade as soon as possible. There are no known workarounds for this issue.
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Analysis
by VulDB Data Team • 11/30/2024
The vulnerability CVE-2022-23626 affects m1k1o/blog, a lightweight self-hosted facebook-styled PHP blog application that has been identified as susceptible to improper error handling in image processing functions. This issue stems from the application's failure to properly validate and handle errors returned by PHP's image manipulation functions such as imagecreatefromjpeg, imagecreatefrompng, and similar image* functions. When these functions encounter malformed or malicious image files, they generate warnings but do not prevent the execution flow from continuing. The application's upload mechanism returns false upon encountering errors, yet it fails to implement proper cleanup procedures that would remove the potentially malicious file from the system. This oversight creates a critical security gap where attackers can upload malicious files that bypass the intended image validation process and remain stored on the server's filesystem, potentially leading to various exploitation scenarios.
The technical flaw represents a classic case of inadequate input validation and error handling in PHP applications, specifically related to the image processing workflow. According to CWE-707, this vulnerability falls under improper handling of potentially malicious input where the application does not properly sanitize or validate the image files before storing them. The issue is particularly concerning because it involves the core file upload functionality of the blog platform, which typically accepts user-submitted content. When PHP's image functions encounter malformed data, they issue warnings but continue execution, allowing the malicious file to persist in the filesystem. This pattern of error handling failure creates a persistent threat vector where attackers can leverage the upload mechanism to store malicious payloads, potentially including web shells or other exploit code, in the server's storage system.
The operational impact of this vulnerability extends beyond simple file storage concerns and represents a significant risk to the overall security posture of the affected system. Attackers can exploit this weakness by uploading specially crafted image files that contain malicious code or payloads designed to exploit other vulnerabilities in the system. The persistence of these files on the server creates opportunities for attackers to execute arbitrary code, gain unauthorized access, or establish persistent backdoors within the application environment. This vulnerability can be particularly dangerous in environments where the blog application has write permissions to critical system directories or where the application runs with elevated privileges. The lack of known workarounds means that administrators must rely entirely on upgrading to a patched version, making this vulnerability particularly risky for production environments where immediate remediation is not possible. The vulnerability also aligns with ATT&CK technique T1190, which involves using vulnerabilities in applications to gain access to systems through the exploitation of weak input validation mechanisms.
The recommended mitigation strategy centers exclusively on upgrading to a patched version of the m1k1o/blog application as soon as possible, since no effective workarounds exist for this particular vulnerability. Organizations should implement immediate patch management procedures to ensure that all affected instances are updated promptly. Security teams should also conduct comprehensive audits of the affected systems to identify and remove any potentially malicious files that may have been uploaded through this vulnerability. Additionally, implementing proper input validation and error handling for all file upload operations, including image files, should be a priority for the development team. The vulnerability demonstrates the critical importance of proper error handling in web applications, particularly when dealing with user-submitted content that undergoes processing. Organizations should also consider implementing additional security controls such as file type validation, content inspection, and restricted file permissions to prevent exploitation of similar vulnerabilities in other applications. This incident underscores the necessity of following secure coding practices and implementing comprehensive testing procedures for all file processing functions within web applications.