CVE-2015-4091 in NetWeaver
Summary
by MITRE
XML external entity (XXE) vulnerability in SAP NetWeaver AS Java allows remote attackers to send TCP requests to intranet servers or possibly have other unspecified impact via an XML request, related to "CIM UPLOAD," aka SAP Security Note 2090851.
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Analysis
by VulDB Data Team • 06/30/2017
The vulnerability identified as CVE-2015-4091 represents a critical XML external entity processing flaw within SAP NetWeaver Application Server Java environment. This weakness specifically affects the CIM UPLOAD functionality, which is part of SAP's enterprise software infrastructure designed to handle management information and system data exchanges. The vulnerability stems from inadequate input validation and processing of XML documents, allowing malicious actors to manipulate XML parsers and potentially gain unauthorized access to internal network resources.
The technical implementation of this vulnerability occurs when the SAP NetWeaver AS Java system processes XML requests containing external entity declarations. Attackers can exploit this by crafting specially formatted XML payloads that reference external entities, enabling the system to make TCP connections to internal network servers without proper authorization. This flaw falls under the CWE-611 category of Improper Restriction of XML External Entity Reference, which is a well-documented weakness in XML processing systems that has been exploited in numerous high-profile security incidents. The vulnerability's impact extends beyond simple data exfiltration as it can potentially allow attackers to perform port scanning, internal network reconnaissance, and even facilitate further attacks on systems within the organization's trusted network perimeter.
The operational consequences of this vulnerability are severe for organizations utilizing SAP NetWeaver AS Java systems, as it creates a pathway for remote attackers to bypass traditional network security controls and access internal resources that would normally be protected by firewalls and network segmentation. The attack surface is particularly concerning because it allows for potential internal network enumeration and can be leveraged to establish a foothold for more sophisticated attacks. The vulnerability's exploitation can lead to unauthorized access to sensitive business data, system compromise, and potential disruption of critical business operations. Organizations may experience cascading security impacts as attackers use the initial compromise to pivot through internal networks, potentially accessing databases, application servers, and other critical infrastructure components.
Organizations should implement immediate mitigations including disabling external entity processing in XML parsers, implementing strict XML validation controls, and applying the relevant SAP security patches outlined in SAP Security Note 2090851. Network segmentation and firewall rules should be enhanced to restrict access to SAP systems, while monitoring systems should be configured to detect unusual TCP connection patterns originating from SAP servers. The vulnerability aligns with ATT&CK technique T1071.004 for Application Layer Protocol: DNS and represents a significant risk to enterprise security posture. Additional protective measures include implementing web application firewalls, conducting regular security assessments of XML processing components, and establishing robust incident response procedures for potential exploitation attempts. Organizations should also consider implementing network intrusion detection systems that can identify and alert on suspicious XML processing activities and unauthorized internal network access attempts.