CVE-2019-3873 in JBoss Enterprise Application Platform
Summary
by MITRE
It was found that Picketlink as shipped with Jboss Enterprise Application Platform 7.2 would accept an xinclude parameter in SAMLresponse XML. An attacker could use this flaw to send a URL to achieve cross-site scripting or possibly conduct further attacks.
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Analysis
by VulDB Data Team • 10/05/2023
The vulnerability identified as CVE-2019-3873 represents a critical security flaw in Picketlink authentication framework that is bundled with Red Hat JBoss Enterprise Application Platform 7.2. This issue stems from improper input validation within the SAML response processing mechanism, specifically allowing malicious actors to manipulate the xinclude parameter within XML documents. The vulnerability manifests when the system processes SAML responses that contain crafted xinclude directives, which can lead to unintended XML processing behaviors that bypass normal security controls. This flaw exists at the intersection of XML security processing and web application authentication systems, creating a dangerous attack surface that can be exploited by remote threat actors without requiring authentication credentials.
The technical implementation of this vulnerability resides in how Picketlink handles XML parsing operations during SAML response validation. When the system encounters an xinclude parameter within the SAMLresponse XML structure, it fails to properly sanitize or validate the input before processing. This creates an opportunity for attackers to inject malicious XML content that can trigger unintended processing behaviors. The vulnerability is classified as a cross-site scripting vector because the malicious XML can contain script payloads that execute in the context of the victim's browser when the SAML response is rendered. From a cybersecurity perspective, this represents a classic example of XML External Entity (XXE) processing vulnerability where the xinclude functionality becomes a mechanism for remote code execution or data exfiltration. The flaw operates under the CWE-611 weakness category related to improper restriction of XML external entity references, which is a well-documented vulnerability pattern in web security.
The operational impact of CVE-2019-3873 extends beyond simple cross-site scripting attacks to potentially enable more sophisticated exploitation techniques. Attackers can leverage this vulnerability to perform server-side request forgery attacks, access internal network resources, or conduct further reconnaissance within the affected environment. The vulnerability's severity is compounded by the fact that it affects enterprise application platforms where authentication systems are critical components, making successful exploitation potentially devastating for organizations. When combined with other attack vectors, this flaw can enable privilege escalation or lateral movement within network infrastructures. The vulnerability aligns with ATT&CK technique T1213.002 for Data from Information Repositories and T1566.001 for Phishing for Information, as it can be used to harvest sensitive authentication data or to gain unauthorized access to protected resources. Organizations running JBoss EAP 7.2 with Picketlink are particularly vulnerable as the flaw exists in the core authentication processing pipeline.
Mitigation strategies for CVE-2019-3873 require immediate attention from system administrators and security teams. The primary remediation involves applying the vendor-provided security patches and updates that address the XML processing validation issues within Picketlink. Organizations should also implement XML input validation controls that specifically block or sanitize xinclude parameters in SAML responses. Network-level protections such as web application firewalls can help detect and block malicious XML content before it reaches the application layer. Additionally, implementing proper input sanitization at the application level and disabling unnecessary XML external entity processing capabilities will significantly reduce the attack surface. Security teams should also consider implementing monitoring and logging controls that can detect unusual XML processing patterns or attempts to exploit the vulnerability. The mitigation approach should follow industry standards such as those outlined in NIST SP 800-53 and ISO 27001 controls for secure application development and XML processing security measures. Regular security assessments and vulnerability scanning should be conducted to ensure that similar vulnerabilities do not exist in other components of the authentication infrastructure.