CVE-2019-20003 in Easescreen Crystal
Summary
by MITRE
Feldtech easescreen Crystal 9.0 Web-Services 9.0.1.16265 allows Stored XSS via the Debug-Log and Display-Log components. This could be exploited when an attacker sends an crafted string for FTP authentication.
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Analysis
by VulDB Data Team • 03/24/2024
The vulnerability identified as CVE-2019-20003 affects Feldtech easescreen Crystal 9.0 Web-Services version 9.0.1.16265, representing a critical stored cross-site scripting flaw that enables attackers to execute malicious scripts within the context of affected systems. This vulnerability specifically manifests through the Debug-Log and Display-Log components, which fail to properly sanitize user input during FTP authentication processes. The flaw allows malicious actors to inject persistent XSS payloads that remain stored within the application's logging mechanisms, making the attack vector particularly dangerous as it can affect multiple users who subsequently view the compromised log entries.
The technical exploitation of this vulnerability occurs when an attacker crafts malicious strings specifically designed for FTP authentication parameters, which are then processed through the vulnerable logging components. These components do not adequately validate or escape user-supplied data before storing it in the system's log files, creating an environment where malicious scripts can be embedded and executed whenever legitimate users access the log information. The stored nature of this XSS vulnerability means that the malicious payload persists even after the initial attack vector is closed, allowing for extended periods of exploitation and increasing the potential impact on system security.
The operational impact of CVE-2019-20003 extends beyond simple script execution, as attackers can leverage this vulnerability to steal session cookies, perform unauthorized actions on behalf of users, or redirect victims to malicious domains. This vulnerability directly aligns with CWE-79 which defines cross-site scripting flaws, and represents a significant risk to web application security frameworks. The attack surface is particularly concerning given that FTP authentication is a common administrative function, meaning that successful exploitation could provide attackers with access to sensitive system information or potentially allow for privilege escalation within the application environment. This vulnerability also maps to ATT&CK technique T1566.001 which covers phishing with malicious attachments, as the malicious strings could be disguised as legitimate authentication attempts.
Organizations utilizing Feldtech easescreen Crystal 9.0 Web-Services should immediately implement input validation and output encoding measures to prevent user-supplied data from being stored and executed as scripts. The most effective mitigations include implementing proper sanitization of all user inputs within the Debug-Log and Display-Log components, applying content security policies to restrict script execution, and ensuring that authentication parameters are properly escaped before being stored in log files. Additionally, regular security assessments should be conducted to identify similar vulnerabilities in other logging components, as the architectural flaw appears to affect core application functionality rather than isolated modules. System administrators should also monitor log files for suspicious entries and implement network-based intrusion detection systems to identify potential exploitation attempts. The vulnerability demonstrates the critical importance of validating and sanitizing all user inputs, particularly in administrative functions, as highlighted in industry best practices for web application security and compliance with standards such as OWASP Top Ten and NIST cybersecurity frameworks.