CVE-2019-19738 in YetiShare
Summary
by MITRE
log_file_viewer.php in MFScripts YetiShare 3.5.2 through 4.5.3 does not sanitize or encode the output from the lFile 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-2019-19738 affects MFScripts YetiShare versions 3.5.2 through 4.5.3, specifically within the log_file_viewer.php component. This issue represents a classic cross-site scripting vulnerability that arises from inadequate input validation and output sanitization practices. The flaw manifests when the lFile parameter is processed without proper sanitization or encoding, creating an exploitable vector for malicious actors to inject and execute arbitrary scripts within the context of the victim's browser session.
The technical implementation of this vulnerability stems from the application's failure to properly sanitize user-supplied input before incorporating it into the HTTP response. When the lFile parameter is passed to log_file_viewer.php, the system directly outputs its contents without implementing appropriate HTML encoding or context-appropriate sanitization measures. This oversight allows attackers to craft malicious payloads that can be executed in the browser of unsuspecting users who access the vulnerable page. The vulnerability specifically relates to CWE-79 which defines the weakness of cross-site scripting due to improper output encoding, and aligns with ATT&CK technique T1203 which covers exploitation of web application vulnerabilities through malicious script injection.
The operational impact of this vulnerability extends beyond simple script execution as it enables attackers to perform a range of malicious activities including session hijacking, credential theft, and data exfiltration. An attacker could inject malicious JavaScript that captures user credentials, redirects victims to phishing sites, or establishes persistent backdoors within the application environment. The vulnerability affects all users who have access to the log_file_viewer.php page, making it particularly dangerous in multi-user environments where administrative access might be present. The attack surface is broadened by the fact that the vulnerability exists in multiple versions of the software, increasing the potential for exploitation across various deployments.
Mitigation strategies for CVE-2019-19738 should prioritize immediate patching of affected MFScripts YetiShare installations to versions that properly sanitize the lFile parameter. Organizations should implement input validation controls that filter or escape special characters in user-supplied parameters before processing them. The implementation of Content Security Policy headers can provide additional defense-in-depth measures to prevent script execution even if the primary vulnerability is not fully patched. Regular security audits and automated vulnerability scanning should be employed to identify similar output encoding issues within the application codebase. Additionally, application developers should adopt secure coding practices that enforce proper output encoding for all dynamic content and implement proper parameter validation frameworks to prevent similar vulnerabilities from emerging in future releases.