CVE-2017-16950 in UrBackup Server
Summary
by MITRE
Cross - site scripting (XSS) vulnerability in UrBackup Server before 2.1.20 allows remote attackers to inject arbitrary web script or HTML via the action parameter.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 12/15/2019
The CVE-2017-16950 vulnerability represents a critical cross-site scripting flaw in UrBackup Server versions prior to 2.1.20, exposing systems to remote code execution risks through web interface manipulation. This vulnerability specifically targets the action parameter handling within the server's web application framework, creating an attack vector that allows malicious actors to inject arbitrary web scripts or HTML content directly into the server's user interface. The flaw stems from insufficient input validation and sanitization mechanisms that fail to properly escape or filter user-supplied data before rendering it within web responses. This type of vulnerability falls under CWE-79 which specifically addresses cross-site scripting conditions where untrusted data is incorporated into web pages without proper validation or encoding. The security implications extend beyond simple script injection, as this vulnerability can be exploited to perform session hijacking, deface web interfaces, steal user credentials, or redirect victims to malicious domains.
The operational impact of this vulnerability is significant for organizations relying on UrBackup Server for their backup infrastructure, as it creates an entry point for attackers to compromise the entire backup ecosystem. Remote attackers can leverage this flaw to execute malicious scripts within the context of authenticated users' browsers, potentially gaining unauthorized access to backup configurations, sensitive data, or even escalating privileges within the backup management interface. The vulnerability's remote exploitability means that attackers do not require local system access or credentials to initiate the attack, making it particularly dangerous in networked environments where the server is exposed to external traffic. According to ATT&CK framework, this vulnerability maps to T1059.007 for scripting and T1566.001 for malicious file execution, representing how attackers can leverage such flaws to establish persistent access or execute malicious payloads through web-based attack vectors.
Organizations utilizing affected UrBackup Server versions should immediately implement mitigations including updating to version 2.1.20 or later, which contains proper input validation and sanitization patches. Additional defensive measures include implementing web application firewalls to filter malicious payloads, configuring strict input validation rules for all parameters including the action parameter, and conducting regular security assessments of web interfaces. Network segmentation strategies should limit exposure of the backup server to trusted internal networks only, while monitoring systems should be deployed to detect anomalous requests containing suspicious script patterns. The vulnerability also underscores the importance of regular security updates and patch management processes, as this flaw existed for an extended period before remediation. Security teams should also consider implementing content security policies and input encoding mechanisms to provide defense-in-depth against similar vulnerabilities in other web applications. The incident serves as a reminder of the critical need for secure coding practices and thorough input validation in web applications, particularly those handling administrative functions and user data.