CVE-2016-2908 in Single Sign On for Bluemix
Summary
by MITRE
IBM Single Sign On for Bluemix could allow a remote attacker to obtain sensitive information, caused by a XML external entity (XXE) error when processing XML data by the XML parser. A remote attacker could exploit this vulnerability to read arbitrary files on the system or cause a denial of service.
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Analysis
by VulDB Data Team • 11/11/2022
The vulnerability identified as CVE-2016-2908 affects IBM Single Sign On for Bluemix, a critical component in cloud identity management systems that enables secure authentication across multiple applications and services. This flaw represents a significant security weakness that could be exploited by remote adversaries to compromise system integrity and confidentiality. The vulnerability stems from improper handling of XML external entity processing within the XML parser component, creating an attack surface that allows unauthorized access to sensitive system resources. The affected system processes XML data through a parser that fails to adequately validate or sanitize external entity references, creating a pathway for malicious actors to manipulate the parsing process.
The technical implementation of this vulnerability aligns with CWE-611, which specifically addresses XML external entity processing vulnerabilities in applications that process untrusted XML data. When the XML parser encounters malformed or malicious XML input containing external entity references, it attempts to resolve these entities by accessing external resources. This behavior enables attackers to construct specially crafted XML payloads that can trigger the parser to read arbitrary files from the system filesystem or access internal network resources. The vulnerability is particularly dangerous because it operates at the parser level, meaning that any application or service within the IBM Single Sign On framework that processes XML data could be affected. Attackers can leverage this weakness to perform server-side request forgery attacks, potentially accessing sensitive configuration files, user credentials, or system logs that should remain protected.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can lead to complete system compromise and denial of service conditions. Remote attackers can exploit the XXE vulnerability to read critical system files such as configuration databases, authentication tokens, or application source code, potentially leading to privilege escalation and lateral movement within the network. The vulnerability's ability to cause denial of service represents a significant operational risk, as attackers can craft XML payloads that consume excessive system resources or trigger parsing errors that crash the authentication service. This disruption can affect thousands of users who rely on the single sign-on system for access to enterprise applications, creating cascading failures throughout the organization's digital infrastructure. The impact is particularly severe in cloud environments where the Single Sign On service acts as a central authentication hub for multiple applications and services.
Mitigation strategies for CVE-2016-2908 must address both immediate remediation and long-term architectural improvements to prevent similar vulnerabilities. Organizations should implement strict XML parser configuration settings that disable external entity processing andDTD parsing entirely, following the principle of least privilege for XML processing components. The IBM security advisory recommends updating to the latest version of IBM Single Sign On for Bluemix that includes patched XML parser implementations, while also implementing network segmentation and monitoring to detect suspicious XML traffic patterns. Security controls should include XML input validation at multiple layers, including application-level filters that sanitize XML content before processing, and network-based intrusion detection systems that monitor for XXE attack signatures. Additionally, organizations should conduct regular security assessments of their XML processing components and implement the ATT&CK framework's defensive techniques for mitigating server-side request forgery and XML injection attacks. The vulnerability demonstrates the critical importance of proper input validation and the need for security-conscious development practices that prevent external entity references from being processed in sensitive applications.