CVE-2017-15947 in Content Management System
Summary
by MITRE
Simple ASC Content Management System v1.2 has XSS in the location field in the sign function, related to guestbook.asp, formgb.asp, and msggb.asp.
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Analysis
by VulDB Data Team • 12/01/2019
The vulnerability identified as CVE-2017-15947 represents a cross-site scripting flaw within the Simple ASC Content Management System version 1.2, specifically affecting the location field within the sign function. This vulnerability manifests across three distinct files including guestbook.asp, formgb.asp, and msggb.asp, which collectively serve as guestbook and messaging functionalities within the CMS. The flaw stems from inadequate input validation and output encoding mechanisms that fail to properly sanitize user-supplied data before it is rendered back to users within the web interface. When an attacker submits malicious script code through the location field, this code executes in the context of other users' browsers who view the affected guestbook entries, creating a persistent XSS vector that can be exploited across multiple user sessions.
The technical implementation of this vulnerability aligns with CWE-79, which categorizes cross-site scripting as a critical weakness in web applications. The flaw occurs because the CMS does not properly escape or encode special characters in user inputs before storing and displaying them within the guestbook functionality. This allows attackers to inject malicious JavaScript payloads that can execute in the victim's browser context, potentially leading to session hijacking, credential theft, or redirection to malicious sites. The vulnerability is particularly concerning because it affects multiple entry points within the application's guestbook system, increasing the attack surface and exploitation opportunities.
The operational impact of CVE-2017-15947 extends beyond simple data theft or defacement, as it provides attackers with a persistent means of compromising user sessions and potentially escalating privileges within the CMS. When exploited, this vulnerability can enable attackers to execute arbitrary code in users' browsers, steal authentication cookies, redirect users to phishing sites, or even inject malicious content that modifies the application's behavior. The persistence of the vulnerability across guestbook.asp, formgb.asp, and msggb.asp means that any user who views the affected content becomes a potential victim, creating a widespread impact that can compromise multiple users simultaneously. This vulnerability directly maps to attack techniques described in the MITRE ATT&CK framework under the T1059.007 category for script injection, specifically targeting web application interfaces.
Mitigation strategies for CVE-2017-15947 require immediate implementation of proper input validation and output encoding mechanisms throughout the affected application components. Organizations should implement strict sanitization of all user inputs, particularly those that are rendered back to users in web contexts, by employing context-appropriate encoding such as HTML entity encoding for web content. The CMS should be updated to version 1.3 or later where this vulnerability has been addressed through proper input validation and output sanitization. Additionally, implementing a Content Security Policy (CSP) header can provide an additional layer of protection against XSS attacks by restricting the sources from which scripts can be loaded. Security monitoring should include detection of suspicious script patterns in guestbook entries, and regular security assessments should be conducted to identify similar vulnerabilities in other parts of the application. The vulnerability demonstrates the critical importance of input validation and output encoding in preventing XSS attacks, as recommended by OWASP's top ten security risks and the defensive programming principles outlined in various cybersecurity frameworks.