CVE-2018-8918 in Router Manager
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in info.cgi in Synology Router Manager (SRM) before 1.1.7-6941 allows remote attackers to inject arbitrary web script or HTML via the host parameter.
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Analysis
by VulDB Data Team • 06/20/2023
The vulnerability identified as CVE-2018-8918 represents a critical cross-site scripting flaw within Synology Router Manager's info.cgi component, affecting versions prior to 1.1.7-6941. This issue resides in the web-based administrative interface of Synology routers, which are widely deployed in both enterprise and home networking environments. The vulnerability specifically targets the host parameter handling within the info.cgi script, creating an avenue for malicious actors to execute arbitrary web scripts or HTML code within the context of authenticated user sessions. The flaw demonstrates a classic input validation weakness that enables attackers to manipulate the application's behavior through crafted HTTP requests.
The technical implementation of this vulnerability stems from insufficient sanitization of user-supplied input parameters within the info.cgi script. When the host parameter is processed without proper validation or encoding mechanisms, malicious payloads can be injected and subsequently executed when the page content is rendered in a user's browser. This type of vulnerability falls under CWE-79 which specifically addresses Cross-Site Scripting vulnerabilities, and represents a fundamental failure in input validation and output encoding practices. The attack vector requires remote access to the affected system, meaning that an attacker does not need physical access or local privileges to exploit this weakness, making it particularly dangerous in networked environments.
The operational impact of CVE-2018-8918 extends beyond simple script execution, as it can enable attackers to perform a range of malicious activities including session hijacking, data theft, and redirection to malicious sites. An attacker who successfully exploits this vulnerability could potentially steal administrative credentials, modify router configurations, or establish persistent access points within the network. The vulnerability affects the confidentiality, integrity, and availability of the router management interface, which serves as a critical control point for network administration. Given that Synology routers are commonly used in both home and enterprise environments, the potential for widespread impact increases significantly, particularly when considering that many users may not regularly update their firmware or may be unaware of the vulnerability.
Mitigation strategies for CVE-2018-8918 primarily focus on applying the vendor-supplied patch or firmware update that addresses the input validation issue in the info.cgi script. Organizations should immediately upgrade to SRM version 1.1.7-6941 or later, which implements proper input sanitization and output encoding mechanisms. Network administrators should also consider implementing additional security controls such as web application firewalls that can detect and block malicious script injection attempts, though these measures provide only secondary protection. The vulnerability aligns with ATT&CK technique T1059.007 which covers Scripting through web shells, and T1566 which covers Phishing with malicious attachments, as attackers may leverage this vulnerability to establish persistent access or deliver additional malware. Regular security assessments and vulnerability scanning should be conducted to identify similar weaknesses in other network management interfaces, as this represents a common pattern in web application security flaws that affects numerous network devices across various vendors.