CVE-2018-16635 in BlackCat
Summary
by MITRE
Blackcat CMS 1.3.2 allows XSS via the willkommen.php?lang=DE page title at backend/pages/modify.php.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 04/19/2020
The vulnerability identified as CVE-2018-16635 affects Blackcat CMS version 1.3.2 and represents a cross-site scripting flaw that specifically targets the administrative backend interface. This issue manifests when users navigate to the willkommen.php page with a language parameter set to DE, where the page title is processed through backend/pages/modify.php, creating an exploitable vector for malicious code injection.
The technical implementation of this vulnerability stems from inadequate input validation and output sanitization within the CMS's backend processing logic. When the language parameter is manipulated, the system fails to properly escape or filter user-supplied data before rendering it in the page title context, allowing attackers to inject malicious scripts that execute in the context of authenticated admin users' browsers. This represents a classic reflected cross-site scripting vulnerability where the malicious payload is reflected back to the user through the vulnerable page title parameter.
The operational impact of this vulnerability is significant as it provides attackers with a potential pathway to escalate privileges and gain unauthorized access to the CMS administrative interface. An attacker who successfully exploits this vulnerability could execute arbitrary JavaScript code within the context of the admin session, potentially leading to complete system compromise. The vulnerability is particularly dangerous because it targets the backend pages, meaning successful exploitation could allow attackers to modify content, create new user accounts, or even install malicious plugins that persist beyond the initial attack vector.
This vulnerability maps to CWE-79: Cross-site Scripting and aligns with ATT&CK technique T1213.002: Exploitation for Credential Access, as it could enable attackers to harvest admin credentials or session tokens through malicious script execution. The attack surface is limited to authenticated users who have access to the backend interface, but this represents a critical privilege escalation vector. The vulnerability also connects to ATT&CK technique T1566.001: Phishing with Malicious Attachments, as attackers might craft malicious links that, when clicked by administrators, trigger the XSS payload.
Mitigation strategies should focus on implementing comprehensive input validation and output encoding throughout the CMS codebase, particularly in backend processing scripts. All user-supplied data must be properly escaped before being rendered in HTML contexts, implementing proper Content Security Policy headers, and ensuring that the CMS framework enforces strict sanitization of all parameters passed to backend administrative pages. Regular security audits should be conducted to identify similar vulnerabilities in other CMS components, and administrators should be educated about the risks of clicking suspicious links in administrative contexts. The vulnerability highlights the importance of maintaining secure coding practices and the necessity of implementing robust input validation mechanisms at all levels of web application development.