CVE-2017-11198 in FineCMS
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in /application/lib/ajax/get_image.php in FineCMS through 2017-07-12 allows remote attackers to inject arbitrary web script or HTML via the folder, id, or name parameter.
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Analysis
by VulDB Data Team • 10/25/2019
The CVE-2017-11198 vulnerability represents a critical cross-site scripting flaw discovered in FineCMS version 2017-07-12 and earlier, affecting the application's ajax image handling functionality. This vulnerability resides within the get_image.php script located in the application/lib/ajax directory, making it a server-side processing endpoint that handles image-related requests through asynchronous javascript calls. The flaw enables remote attackers to execute malicious code within the context of a victim's browser by manipulating specific parameters in the request.
The technical implementation of this vulnerability stems from inadequate input validation and output sanitization within the targeted php script. Attackers can exploit three distinct parameter vectors including folder, id, and name parameters that are directly passed to the script without proper sanitization or encoding. When these parameters contain malicious payloads, they are processed and returned to the user's browser without appropriate security measures, creating an environment where javascript code can be executed. This represents a classic reflected cross-site scripting vulnerability where malicious input is immediately reflected back to the user without any server-side processing that would normally sanitize the content.
The operational impact of this vulnerability extends beyond simple script injection, as it provides attackers with the ability to perform various malicious activities within the context of authenticated users. An attacker could potentially steal session cookies, redirect users to malicious websites, deface the website, or even escalate privileges if the application has administrative functionality. The vulnerability affects the entire FineCMS ecosystem, as it allows unauthorized users to inject malicious content that could be executed by any visitor accessing the affected pages. This makes it particularly dangerous in multi-user environments where administrators might be tricked into clicking malicious links that could compromise their sessions.
The vulnerability aligns with CWE-79 which specifically addresses cross-site scripting flaws in web applications, and can be categorized under the ATT&CK technique T1203 - Exploitation for Client Execution, where attackers leverage web application vulnerabilities to execute code in user browsers. Organizations using FineCMS versions prior to the patch release should immediately implement mitigation strategies including input validation, output encoding, and parameter sanitization. The recommended approach involves implementing strict input validation for all parameters passed to the get_image.php script, ensuring that all user-supplied data is properly escaped before being returned to the browser. Additionally, implementing Content Security Policy headers and using secure coding practices such as the principle of least privilege for file operations would significantly reduce the attack surface and prevent exploitation of this vulnerability.
This vulnerability demonstrates the critical importance of validating and sanitizing all user inputs in web applications, particularly in ajax endpoints where data flows directly from user requests to browser execution. The flaw serves as a reminder that even seemingly innocuous file handling functions can become attack vectors when proper security measures are not implemented, highlighting the need for comprehensive security testing including dynamic application security testing and input validation reviews.