CVE-2018-8038 in CXF Fediz
Summary
by MITRE
Versions of Apache CXF Fediz prior to 1.4.4 do not fully disable Document Type Declarations (DTDs) when either parsing the Identity Provider response in the application plugins, or in the Identity Provider itself when parsing certain XML-based parameters.
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Analysis
by VulDB Data Team • 04/03/2023
Apache CXF Fediz versions prior to 1.4.4 contain a critical vulnerability related to XML external entity processing that stems from insufficient disabling of Document Type Declarations. This vulnerability exists in both the application plugins that process Identity Provider responses and within the Identity Provider itself when handling XML-based parameters. The flaw allows attackers to exploit XML parsing mechanisms by manipulating DTD declarations, potentially leading to various security risks including denial of service attacks and potential data exposure. This issue directly relates to CWE-611, which addresses improper restriction of XML external entity references, and aligns with ATT&CK technique T1210 for exploiting weaknesses in XML processors. The vulnerability occurs because the XML parsers used in these components fail to properly configure their security settings to disable DTD processing entirely, leaving the system susceptible to XML external entity injection attacks. When an attacker crafts malicious XML content containing DTD declarations, the parser may attempt to resolve external entities or perform other malicious actions, potentially leading to information disclosure or service disruption. The impact is particularly significant in federated identity environments where the system processes untrusted XML responses from external Identity Providers, as these responses could contain crafted payloads designed to exploit the DTD processing vulnerability.
The technical implementation of this vulnerability involves the XML parsing libraries used within Apache CXF Fediz components not being properly configured to disable external entity resolution. This typically occurs when XML parsers are initialized without explicit security parameters that prevent DTD processing or external entity resolution. In the context of federated identity systems, this creates a dangerous attack surface where malicious actors can manipulate the XML responses received from Identity Providers, potentially leading to unauthorized access to internal resources or system disruption. The vulnerability affects both client-side processing within application plugins and server-side processing within the Identity Provider components themselves, making it particularly dangerous as it can be exploited at multiple points in the authentication flow. The exploitation requires an attacker to have the ability to influence or inject XML content that gets processed by the vulnerable components, which is feasible in scenarios where the system interacts with untrusted external Identity Providers or where XML content can be manipulated through other attack vectors.
The operational impact of CVE-2018-8038 extends beyond simple denial of service conditions to potentially enable more sophisticated attacks within federated identity environments. Attackers could leverage this vulnerability to perform server-side request forgery attacks, cause resource exhaustion through malicious DTD references, or potentially gain access to internal network resources through blind XXE (XML External Entity) attacks. The vulnerability is particularly concerning in enterprise environments where Apache CXF Fediz is used for single sign-on and identity federation, as it could allow attackers to compromise authentication flows and potentially escalate privileges within the federated environment. Organizations using affected versions should consider the potential for data exfiltration through external entity references and the possibility of service disruption through resource exhaustion attacks. The vulnerability also impacts compliance with security standards such as NIST SP 800-53 and ISO 27001, as it represents a failure to properly configure XML parsers according to security best practices. The risk assessment should include consideration of the attack surface within the specific deployment environment, particularly whether the system processes XML from untrusted sources or if there are potential pathways for an attacker to inject malicious XML content into the processing pipeline.
Mitigation strategies for CVE-2018-8038 should focus on updating to Apache CXF Fediz version 1.4.4 or later, which contains the necessary fixes to properly disable DTD processing in all affected components. Organizations should also implement additional security controls such as configuring XML parsers to disable external entity resolution, implementing proper input validation for all XML content, and monitoring for suspicious XML processing activities. Network-level protections such as firewalls and intrusion detection systems can help detect and prevent exploitation attempts, while application-level controls should include proper XML schema validation and secure coding practices that prevent XML injection vulnerabilities. The fix implemented in version 1.4.4 typically involves configuring the underlying XML parsing libraries to explicitly disable DTD processing, external general entities, and external parameter entities to prevent the exploitation of this vulnerability. Security teams should also conduct thorough testing to ensure that the update does not introduce compatibility issues with existing federated identity configurations, and should review all XML processing components within their environment to identify similar vulnerabilities that may exist in other systems. Regular security assessments and vulnerability scanning should be performed to identify and remediate similar XML parsing vulnerabilities across the organization's technology stack.