CVE-2017-16689 in SAP
Summary
by MITRE
A Trusted RFC connection in SAP KERNEL 32NUC, SAP KERNEL 32Unicode, SAP KERNEL 64NUC, SAP KERNEL 64Unicode 7.21, 7.21EXT, 7.22, 7.22EXT; SAP KERNEL from 7.21 to 7.22, 7.45, 7.49, can be established to a different client or a different user on the same system, although no explicit Trusted/Trusting Relation to the same system has been defined.
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Analysis
by VulDB Data Team • 01/26/2021
This vulnerability in SAP KERNEL affects the trusted connection mechanism that should only permit connections between systems with explicitly defined trust relationships. The flaw allows unauthorized access by enabling connections to different clients or users on the same system without proper authorization, undermining the fundamental security principle of least privilege and trusted system boundaries. The vulnerability exists across multiple kernel versions including 32NUC, 32Unicode, 64NUC, 64Unicode, and specific releases from 7.21 through 7.49, making it a widespread issue affecting SAP system architectures. The Trusted RFC connection feature is designed to facilitate secure communication between SAP systems that have established trust relationships, but this vulnerability permits bypassing those trust boundaries through improper validation of connection parameters.
The technical implementation flaw stems from insufficient validation of the target system's client and user identifiers during the RFC connection establishment process. When a system attempts to establish a trusted RFC connection, the kernel should verify that the target system has an explicit trust relationship defined in the system configuration, but this validation is bypassed in the affected versions. The vulnerability specifically affects the authentication and authorization mechanisms that should normally prevent cross-client or cross-user access within the same system instance. This represents a classic case of inadequate input validation and privilege escalation, where the system fails to properly enforce access controls that should restrict connections to only those systems with defined trust relationships. The issue aligns with CWE-284 Access Control Issues, specifically related to improper access control enforcement within trusted system communications.
The operational impact of this vulnerability is significant as it allows potential attackers to perform unauthorized access to different client databases and user accounts within the same SAP system instance. This could enable data exfiltration, privilege escalation, and lateral movement within the SAP environment, particularly in multi-client systems where different business units or departments share the same SAP system. Attackers could exploit this vulnerability to access sensitive financial data, personal information, or operational details belonging to other clients within the same system without proper authorization. The vulnerability also creates opportunities for privilege escalation attacks where an attacker with access to one client could potentially gain access to administrative functions or data belonging to other clients. This type of vulnerability directly impacts the integrity and confidentiality of SAP system data, as it violates the principle of separation of duties and client isolation that is fundamental to SAP security architecture.
Organizations should immediately apply the relevant SAP security patches and updates to address this vulnerability, as the affected kernel versions represent critical security risks. System administrators should conduct comprehensive audits of their SAP system configurations to identify and remove any unnecessary trusted RFC connections, while implementing proper monitoring and logging of RFC connection attempts. The mitigation strategy should include reviewing and tightening the trust relationship definitions in the SAP system, ensuring that only explicitly defined systems can establish trusted connections. Additionally, organizations should implement network segmentation and firewall rules to restrict RFC communication between systems, and conduct regular security assessments to identify potential unauthorized trust relationships. This vulnerability demonstrates the importance of proper access control implementation and highlights the need for continuous security monitoring of trusted system relationships, aligning with ATT&CK techniques related to privilege escalation and lateral movement through trusted relationships.