CVE-2018-2371 in NetWeaver AS JAVA
Summary
by MITRE
The SAML 2.0 service provider of SAP Netweaver AS Java Web Application, 7.50, does not sufficiently encode user controlled inputs, which results in Cross-Site Scripting (XSS) vulnerability.
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Analysis
by VulDB Data Team • 01/04/2020
The vulnerability identified as CVE-2018-2371 affects the SAML 2.0 service provider implementation within SAP Netweaver AS Java Web Application version 7.50. This issue represents a critical security flaw that arises from insufficient input validation and output encoding mechanisms within the web application's authentication framework. The vulnerability specifically impacts the service provider component responsible for handling SAML 2.0 assertions and responses, which are fundamental elements of the Single Sign-On (SSO) authentication process used by SAP systems.
The technical flaw manifests when user-controlled inputs are processed and subsequently rendered within the web application's response without proper encoding or sanitization. This occurs in the context of SAML 2.0 assertion handling where parameters such as user identifiers, session data, or assertion attributes may contain malicious script code that gets executed in the context of a victim's browser. The vulnerability falls under CWE-79 which specifically addresses Cross-Site Scripting flaws, where the application fails to properly encode output data before rendering it to web clients. The flaw is particularly dangerous because it operates within the authentication context of SAP systems, potentially allowing attackers to exploit this weakness during the SSO process.
The operational impact of this vulnerability extends beyond typical XSS scenarios due to the privileged nature of the affected SAP system components. An attacker could leverage this vulnerability to execute arbitrary JavaScript code in the context of authenticated users, potentially leading to session hijacking, privilege escalation, or data exfiltration from the SAP environment. The attack surface is particularly concerning because SAML 2.0 assertions often contain sensitive user information and system identifiers that could be exploited to gain deeper access to the SAP Netweaver infrastructure. This vulnerability could be exploited through various attack vectors including malicious SAML assertions, crafted user inputs, or manipulated authentication parameters that are processed by the vulnerable service provider component.
Mitigation strategies for CVE-2018-2371 should focus on implementing comprehensive input validation and output encoding mechanisms within the SAP Netweaver AS Java Web Application. Organizations should ensure that all user-controlled inputs are properly sanitized and encoded before being rendered in web responses, particularly within SAML 2.0 assertion handling components. The recommended approach includes implementing strict content security policies, utilizing parameterized input validation, and ensuring that all SAML assertion attributes undergo proper HTML encoding. Additionally, SAP recommends applying the relevant security patches and updates provided by the vendor to address this specific vulnerability. Organizations should also consider implementing network-level protections such as web application firewalls and monitoring for suspicious SAML-related traffic patterns to detect potential exploitation attempts. The remediation process should be aligned with industry best practices for secure coding and application security controls, particularly those addressing the CWE-79 category of vulnerabilities.