CVE-2018-20778 in Frog
Summary
by MITRE
admin/?/plugin/file_manager in Frog CMS 0.9.5 allows XSS by creating a new file containing a crafted attribute of an IMG element.
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Analysis
by VulDB Data Team • 07/09/2023
The vulnerability identified as CVE-2018-20778 resides within Frog CMS version 0.9.5, specifically affecting the administrative interface component accessible through the path admin/?/plugin/file_manager. This issue represents a cross-site scripting vulnerability that arises from insufficient input validation and output sanitization within the file management plugin. The flaw enables authenticated attackers with administrative privileges to inject malicious JavaScript code through the creation of specially crafted files containing IMG elements with malicious attributes.
The technical implementation of this vulnerability stems from the application's failure to properly sanitize user-supplied input when processing file uploads or file creation operations within the file manager interface. When an attacker creates a new file containing an IMG element with crafted attributes, the application does not adequately filter or escape these elements before rendering them in the web interface. This allows malicious script code embedded within the IMG element attributes to execute in the context of other users' browsers who view the file listing or related pages. The vulnerability specifically targets the IMG element's attributes such as src, onclick, or onerror, which can contain executable JavaScript when not properly sanitized.
From an operational perspective, this vulnerability poses significant risks to the security posture of Frog CMS installations. Since it requires administrative privileges to exploit, the primary threat vector involves compromised administrator accounts or privilege escalation attacks. The impact extends beyond simple script execution, as attackers can potentially steal session cookies, perform actions on behalf of users, redirect victims to malicious sites, or establish persistent backdoors through more sophisticated attack chains. The vulnerability affects the entire administrative interface and can compromise the integrity of the content management system, potentially leading to complete system takeover or data exfiltration.
The vulnerability maps to CWE-79 in the Common Weakness Enumeration catalog, which specifically addresses Cross-Site Scripting flaws in web applications. This weakness category encompasses the failure to properly encode or escape output before rendering user-supplied data, creating opportunities for malicious script injection. From the MITRE ATT&CK framework perspective, this vulnerability aligns with techniques involving credential access and execution through web-based attacks. The attack chain typically involves initial compromise of administrative credentials followed by exploitation of this XSS vulnerability to maintain persistence and escalate privileges within the CMS environment.
Mitigation strategies for CVE-2018-20778 should prioritize immediate patching of Frog CMS to version 0.9.6 or later, which contains the necessary fixes for input validation and output sanitization. Organizations should implement strict input validation for all file upload operations, particularly for image files, and employ comprehensive output encoding for all user-supplied content rendered in web interfaces. Additionally, implementing Content Security Policy headers can provide additional defense-in-depth against script execution. Regular security audits of CMS plugins and core components should be conducted to identify similar vulnerabilities, and access controls should be strictly enforced through proper authentication and authorization mechanisms. Network segmentation and monitoring of administrative interfaces can help detect suspicious activities related to file management operations that might indicate exploitation attempts.