CVE-2018-8913 in Web Station
Summary
by MITRE
Missing custom error page vulnerability in Synology Web Station before 2.1.3-0139 allows remote attackers to conduct phishing attacks via a crafted URL.
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Analysis
by VulDB Data Team • 08/21/2023
The vulnerability identified as CVE-2018-8913 represents a critical security flaw in Synology Web Station software affecting versions prior to 2.1.3-0139. This issue stems from the absence of proper custom error handling mechanisms within the web application framework, creating a significant attack surface that malicious actors can exploit to conduct sophisticated phishing operations. The vulnerability specifically manifests when the application encounters malformed or intentionally crafted URLs that trigger error conditions, which are then displayed to users without appropriate sanitization or redirection mechanisms.
The technical implementation of this vulnerability involves the web server's inability to properly handle error states when processing user input through URLs. When a user navigates to a crafted URL that causes the web application to generate an error response, the system fails to present a custom error page that would normally mask the underlying application details and prevent information disclosure. Instead, the default error handling mechanism exposes sensitive information about the web application's configuration, including server software versions, directory structures, and potentially other system identifiers that could be leveraged by attackers.
From an operational perspective, this vulnerability enables remote attackers to craft malicious URLs that, when clicked by unsuspecting users, redirect them to phishing pages that closely mimic legitimate Synology interfaces. The lack of proper error page handling creates a false sense of security for users who may not notice that they have been redirected to a malicious site, particularly when the phishing page is designed to replicate the legitimate interface with high fidelity. This attack vector is particularly dangerous because it exploits the trust users place in familiar interface elements while remaining undetected by standard security measures that might not flag the initial error condition as suspicious.
The security implications extend beyond simple phishing attacks to encompass potential information disclosure and privilege escalation opportunities. According to CWE classification, this vulnerability aligns with CWE-116, which addresses improper encoding or escaping of output, and CWE-200, which covers exposure of sensitive information. The ATT&CK framework categorizes this as a technique for Initial Access through Social Engineering, specifically leveraging the trust relationship between users and legitimate web interfaces to gain unauthorized access to systems.
Mitigation strategies for CVE-2018-8913 require immediate patching of affected Synology Web Station installations to version 2.1.3-0139 or later, which includes proper custom error page implementation. Organizations should also implement comprehensive URL filtering and validation mechanisms to prevent users from accessing potentially malicious crafted URLs. Network-level protections such as web application firewalls can provide additional layers of defense by monitoring for suspicious URL patterns and blocking known malicious constructs. Security teams should conduct regular vulnerability assessments to ensure that all web applications maintain proper error handling procedures and implement robust logging mechanisms to detect potential exploitation attempts. Additionally, user education programs should emphasize the importance of verifying URLs and interface authenticity, particularly when encountering unexpected error messages or interface elements that may indicate a phishing attempt.