CVE-2019-0271 in NetWeaver
Summary
by MITRE
ABAP Server (used in NetWeaver and Suite/ERP) and ABAP Platform does not sufficiently validate an XML document accepted from an untrusted source, leading to an XML External Entity (XEE) vulnerability. Fixed in Kernel 7.21 or 7.22, that is ABAP Server 7.00 to 7.31 and Kernel 7.45, 7.49 or 7.53, that is ABAP Server 7.40 to 7.52 or ABAP Platform.
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Analysis
by VulDB Data Team • 07/31/2023
The vulnerability described in CVE-2019-0271 represents a critical XML External Entity processing weakness within the ABAP Server component of SAP NetWeaver and ERP systems. This flaw exists in the ABAP Platform's XML parsing functionality where insufficient validation occurs when processing XML documents received from untrusted sources. The vulnerability specifically affects systems running ABAP Server versions 7.00 through 7.31 with Kernel versions 7.21 or 7.22, as well as ABAP Server 7.40 through 7.52 with Kernel versions 7.45, 7.49, or 7.53. The issue stems from the lack of proper XML parser configuration that would prevent the processing of external entities during XML document parsing operations.
This vulnerability falls under the CWE-611 category of Improper Restriction of XML External Entity Reference, which is a well-documented weakness in XML processing systems. The attack vector involves an unauthenticated remote attacker who can submit malicious XML content to the vulnerable ABAP server, potentially causing the system to process external entity references that could lead to information disclosure, denial of service, or even remote code execution depending on the system configuration. The vulnerability is particularly dangerous in enterprise environments where SAP systems often serve as central business application platforms handling sensitive corporate data.
The operational impact of CVE-2019-0271 extends beyond simple data exposure, as it can enable attackers to perform server-side request forgery attacks and potentially gain unauthorized access to internal network resources. When exploited, this vulnerability allows attackers to manipulate the XML parser to reference external resources, which could include internal network addresses, file systems, or other sensitive endpoints. The attack surface is broad given that ABAP servers are commonly used for business-critical applications and often have access to enterprise databases and internal services. Organizations running affected SAP versions are particularly vulnerable to attacks that could lead to data breaches, system compromise, or disruption of business operations.
Mitigation strategies for this vulnerability require immediate implementation of the vendor-provided kernel updates, specifically targeting Kernel versions 7.21 or 7.22 for ABAP Server 7.00 to 7.31, and Kernel versions 7.45, 7.49, or 7.53 for ABAP Server 7.40 to 7.52. Additionally, organizations should implement XML parser configuration changes to disable external entity processing and DTD (Document Type Definition) loading entirely. Security controls should include network segmentation to limit access to SAP systems, implementation of web application firewalls that can detect and block malicious XML content, and regular monitoring for unusual XML processing activities. The ATT&CK framework categorizes this vulnerability under T1059.007 for XML External Entity Processing, which emphasizes the importance of validating input and restricting system access to prevent exploitation. Organizations should also conduct comprehensive vulnerability assessments to identify all systems running affected ABAP Server versions and implement proper access controls to minimize potential attack vectors.