CVE-2016-6812 in CXF
Summary
by MITRE
The HTTP transport module in Apache CXF prior to 3.0.12 and 3.1.x prior to 3.1.9 uses FormattedServiceListWriter to provide an HTML page which lists the names and absolute URL addresses of the available service endpoints. The module calculates the base URL using the current HttpServletRequest. The calculated base URL is used by FormattedServiceListWriter to build the service endpoint absolute URLs. If the unexpected matrix parameters have been injected into the request URL then these matrix parameters will find their way back to the client in the services list page which represents an XSS risk to the client.
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Analysis
by VulDB Data Team • 12/15/2022
The vulnerability described in CVE-2016-6812 resides within the HTTP transport module of Apache CXF versions prior to 3.0.12 and 3.1.x prior to 3.1.9, representing a cross-site scripting vulnerability that stems from improper handling of URL parameters in service endpoint listings. This flaw specifically affects the FormattedServiceListWriter component responsible for generating HTML pages that display available service endpoints along with their absolute URL addresses. The vulnerability emerges from the module's approach to calculating the base URL using the current HttpServletRequest object, which processes incoming requests without adequate sanitization of matrix parameters that may have been injected into the request URL.
The technical implementation of this vulnerability involves the HTTP transport module's reliance on HttpServletRequest to determine the base URL for constructing absolute service endpoint addresses. When matrix parameters are unexpectedly injected into the request URL, these parameters are not properly filtered or escaped before being rendered in the HTML output generated by FormattedServiceListWriter. Matrix parameters in URLs are typically used to provide additional information to the resource being requested, but they can be manipulated by attackers to inject malicious content. The flaw occurs because the system does not distinguish between legitimate matrix parameters used for service operation and maliciously injected parameters that could contain script code.
The operational impact of this vulnerability is significant as it creates an attack vector that allows remote attackers to execute arbitrary script code in the context of the victim's browser. When users access the service list page, any injected matrix parameters that contain malicious JavaScript code will be reflected back to the client, potentially leading to session hijacking, data theft, or other malicious activities. This represents a classic cross-site scripting vulnerability that can be exploited by attackers who have knowledge of the target system's service endpoints. The vulnerability affects any user who accesses the service listing page, making it particularly dangerous in environments where multiple users may be accessing the service information.
This vulnerability aligns with CWE-79, which describes Cross-Site Scripting flaws, and demonstrates characteristics consistent with the ATT&CK technique T1566.001 for initial access through spearphishing attachments or links. The flaw essentially allows attackers to inject malicious content into the service listing page, which can then be executed by unsuspecting users who visit the page. Organizations using affected versions of Apache CXF are particularly at risk because the vulnerability does not require authentication or special privileges to exploit, making it accessible to any attacker who can send requests to the affected system. The attack surface is broad as any service that utilizes the HTTP transport module and generates service listings is potentially vulnerable.
The recommended mitigations for this vulnerability include upgrading to Apache CXF versions 3.0.12 or 3.1.9 and later, which contain fixes that properly sanitize matrix parameters before rendering them in the service list output. Organizations should also implement proper input validation and output encoding mechanisms to prevent similar issues in custom implementations. Additionally, network administrators should consider implementing web application firewalls that can detect and block suspicious URL patterns containing matrix parameters. The fix implemented by Apache CXF developers involves modifying the URL parsing logic to strip or properly encode matrix parameters before they are included in the generated HTML output, preventing the reflection of malicious content back to clients. Security teams should also conduct regular vulnerability assessments to identify other potential XSS vulnerabilities in their Apache CXF implementations and ensure that all components are kept up to date with the latest security patches.