CVE-2017-14920 in Community Edition
Summary
by MITRE
Stored XSS vulnerability in eGroupware Community Edition before 16.1.20170922 allows an unauthenticated remote attacker to inject JavaScript via the User-Agent HTTP header, which is mishandled during rendering by the application administrator.
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Analysis
by VulDB Data Team • 12/30/2022
The stored cross-site scripting vulnerability identified as CVE-2017-14920 affects eGroupware Community Edition versions prior to 16.1.20170922 and represents a critical security flaw that enables unauthenticated remote attackers to execute malicious JavaScript code within the context of the application administrator's browser. This vulnerability resides in the application's handling of the User-Agent HTTP header during the rendering process, creating a persistent XSS vector that can be exploited without requiring authentication credentials. The flaw allows attackers to inject malicious scripts that will execute whenever the administrator views the affected application interface, potentially leading to complete compromise of the administrative session.
The technical implementation of this vulnerability stems from improper input validation and output encoding within the eGroupware application's user agent processing logic. When the application receives HTTP requests containing User-Agent headers, it fails to properly sanitize or escape the input before storing and subsequently rendering this data within the web interface. This stored data is then displayed to administrators who view system logs or user activity reports, making the vulnerability particularly dangerous as it can persist across multiple sessions and potentially affect multiple users. The vulnerability classifies under CWE-79 which specifically addresses Cross-Site Scripting flaws, and more specifically aligns with CWE-798 which addresses the use of hardcoded credentials or sensitive information in code.
The operational impact of this vulnerability extends beyond simple script execution as it provides attackers with a persistent foothold within the target environment. Administrators who view system logs, user activity reports, or other interfaces that display stored User-Agent information become victims of the XSS attack, potentially enabling session hijacking, credential theft, or privilege escalation. Attackers can leverage this vulnerability to execute malicious scripts that may attempt to steal administrator cookies, redirect users to phishing sites, or even execute additional exploits against the compromised system. The stored nature of the vulnerability means that even after the initial injection, the malicious code continues to execute whenever the affected interface is accessed by administrators, creating a long-term threat vector.
Security professionals should implement multiple layers of mitigation strategies to address this vulnerability effectively. The primary remediation involves upgrading to eGroupware Community Edition version 16.1.20170922 or later, which contains the necessary patches to properly sanitize User-Agent headers. Additionally, organizations should implement robust input validation at all entry points where user-supplied data is processed, particularly focusing on HTTP headers that are commonly overlooked in security implementations. Network-based mitigations such as web application firewalls can provide additional protection by detecting and blocking suspicious User-Agent patterns, though these should complement rather than replace proper application-level fixes. The vulnerability demonstrates the importance of following secure coding practices as outlined in the OWASP Top Ten and aligns with ATT&CK technique T1059.007 for command and scripting interpreter, where attackers can use XSS vulnerabilities to execute malicious scripts within the browser context of privileged users. Organizations should also implement regular security assessments and penetration testing to identify similar stored XSS vulnerabilities in other applications and ensure comprehensive protection against persistent threat vectors.