CVE-2014-2296 in CAS Server
Summary
by MITRE
XML external entity (XXE) vulnerability in java/org/jasig/cas/util/SamlUtils.java in Jasig CAS server before 3.4.12.1 and 3.5.x before 3.5.2.1, when Google Accounts Integration is enabled, allows remote unauthenticated users to bypass authentication via crafted XML data.
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Analysis
by VulDB Data Team • 03/08/2020
The CVE-2014-2296 vulnerability represents a critical XML external entity processing flaw within the Jasig CAS server authentication system, specifically affecting versions prior to 3.4.12.1 and 3.5.x prior to 3.5.2.1. This vulnerability resides in the SamlUtils.java file which handles SAML protocol operations and becomes particularly dangerous when Google Accounts Integration is enabled. The flaw enables remote attackers to manipulate the XML parsing mechanism and bypass authentication controls through carefully crafted XML payloads that exploit the server's handling of external entities.
The technical implementation of this vulnerability stems from insufficient input validation and sanitization within the XML processing pipeline of the CAS server. When the system processes XML data containing external entity references, it fails to properly restrict or disable the resolution of external entities, allowing attackers to inject malicious XML content that can reference external resources. This behavior aligns with CWE-611, which categorizes improper restriction of XML external entity reference as a critical weakness in web applications. The vulnerability specifically manifests when the server parses SAML assertions that may contain crafted external entity declarations, enabling attackers to leverage the XML parser's capabilities to access internal resources or perform unauthorized operations.
The operational impact of this vulnerability extends beyond simple authentication bypass, as it provides attackers with potential access to sensitive internal systems and data. When Google Accounts Integration is enabled, the vulnerability becomes more exploitable because the CAS server's XML processing logic becomes more complex and potentially more exposed to external inputs. Attackers can craft malicious XML data that, when processed by the vulnerable CAS server, can trigger the resolution of external entities that may contain malicious payloads or enable access to internal network resources. This creates a significant risk for organizations relying on CAS for single sign-on operations, as successful exploitation could lead to unauthorized access to protected applications and systems.
The threat landscape for this vulnerability aligns with ATT&CK technique T1566, which describes the exploitation of vulnerabilities in remote services to gain initial access to systems. The vulnerability's remote and unauthenticated nature makes it particularly attractive to attackers who can leverage it without requiring prior credentials or system access. Organizations implementing CAS server solutions with Google integration should prioritize immediate remediation through version upgrades to 3.4.12.1 or 3.5.2.1, respectively, as these releases contain the necessary patches to disable external entity processing during XML parsing operations. Additional mitigations include implementing proper XML parser configurations that disable external entity resolution, network segmentation to limit access to vulnerable CAS servers, and monitoring for suspicious XML processing activities that may indicate exploitation attempts.