CVE-2019-19733 in YetiShare
Summary
by MITRE
_get_all_file_server_paths.ajax.php (aka get_all_file_server_paths.ajax.php) in MFScripts YetiShare 3.5.2 through 4.5.3 does not sanitize or encode the output from the fileIds parameter on the page, which would allow an attacker to input HTML or execute scripts on the site, aka XSS.
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Analysis
by VulDB Data Team • 03/18/2024
The vulnerability identified as CVE-2019-19733 affects MFScripts YetiShare versions 3.5.2 through 4.5.3, specifically within the _get_all_file_server_paths.ajax.php component. This represents a classic cross-site scripting vulnerability that arises from inadequate input validation and output encoding mechanisms. The flaw occurs when the fileIds parameter is processed through the ajax endpoint without proper sanitization, creating an attack vector that allows malicious actors to inject arbitrary HTML content or execute JavaScript code within the context of the vulnerable application. This type of vulnerability falls under CWE-79 which categorizes cross-site scripting flaws as weaknesses in input validation and output encoding. The vulnerability is particularly concerning as it affects the core file management functionality of the platform, potentially allowing attackers to compromise user sessions or redirect them to malicious sites.
The technical exploitation of this vulnerability requires an attacker to manipulate the fileIds parameter in the _get_all_file_server_paths.ajax.php endpoint to inject malicious payloads. When the application processes this unsanitized parameter, it fails to encode or escape the output before rendering it in the web page context. This creates a persistent XSS vulnerability that can be triggered when authenticated users view the affected page or interact with the application's file management features. The vulnerability's impact is amplified by the fact that it occurs in an ajax endpoint, meaning that the malicious code can be executed in the context of the victim's browser session without requiring additional user interaction beyond visiting a compromised page. The ATT&CK framework categorizes this as a technique for code injection and credential access through web application vulnerabilities, specifically under the T1190 - Exploit Public-Facing Application and T1531 - Account Access Removal categories.
The operational impact of this vulnerability extends beyond simple script execution, as it can enable attackers to perform session hijacking, deface the application interface, or redirect users to phishing sites that can harvest credentials. Attackers can leverage this vulnerability to gain unauthorized access to user accounts, potentially compromising sensitive file data or system resources managed through the YetiShare platform. The vulnerability affects both authenticated and potentially unauthenticated users depending on the specific implementation details, though the attack surface is typically larger when users with elevated privileges interact with the vulnerable functionality. Organizations using affected versions of YetiShare face significant risk of data breaches, as the vulnerability allows for persistent malicious code execution that can remain undetected for extended periods. The vulnerability also creates potential for privilege escalation if the application's administrative functions are accessible through the same vulnerable code path, allowing attackers to gain elevated access to the system.
Mitigation strategies for CVE-2019-19733 should focus on immediate patching of the affected MFScripts YetiShare versions to the latest releases that contain proper input sanitization and output encoding mechanisms. Organizations should implement comprehensive input validation that filters or escapes all user-supplied data before processing, particularly for parameters used in dynamic content generation. The implementation of Content Security Policy headers can provide additional defense-in-depth measures to prevent script execution in the browser context. Regular security scanning and penetration testing should be conducted to identify similar vulnerabilities in other components of the application. Organizations should also consider implementing web application firewalls to detect and block suspicious requests targeting the vulnerable ajax endpoint. The fix should include proper encoding of output data using context-appropriate methods such as HTML entity encoding for web page content or JavaScript encoding for dynamic script generation, ensuring that any user-provided input cannot be interpreted as executable code. Security monitoring should be enhanced to detect unusual patterns in file management requests that might indicate exploitation attempts.