CVE-2021-27606 in NetWeaver ABAP Server
Summary
by MITRE • 06/09/2021
SAP NetWeaver ABAP Server and ABAP Platform (Enqueue Server), versions - KRNL32NUC - 7.22,7.22EXT, KRNL64NUC - 7.22,7.22EXT,7.49, KRNL64UC - 8.04,7.22,7.22EXT,7.49,7.53,7.73, KERNEL - 7.22,8.04,7.49,7.53,7.73, allows an unauthenticated attacker without specific knowledge of the system to send a specially crafted packet over a network which will trigger an internal error in the system due to improper input validation in method EncOAMParamStore() causing the system to crash and rendering it unavailable. In this attack, no data in the system can be viewed or modified.
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Analysis
by VulDB Data Team • 06/11/2021
CVE-2021-27606 represents a critical denial of service vulnerability affecting SAP NetWeaver ABAP Server and ABAP Platform Enqueue Server components. This vulnerability resides in the EncOAMParamStore() method within the kernel modules of affected SAP systems, specifically impacting versions KRNL32NUC 7.22 and 7.22EXT, KRNL64NUC 7.22, 7.22EXT, and 7.49, KRNL64UC 8.04, 7.22, 7.22EXT, 7.49, 7.53, and 7.73, as well as KERNEL versions 7.22, 8.04, 7.49, 7.53, and 7.73. The flaw stems from inadequate input validation mechanisms that fail to properly sanitize or validate incoming network packets before processing them within the system's internal components.
The technical exploitation of this vulnerability occurs when an unauthenticated attacker crafts and transmits a specially designed network packet to the affected SAP system. The malformed packet triggers an internal error condition within the EncOAMParamStore() method, causing the system to experience a critical failure that results in complete system crash and subsequent unavailability. This represents a classic buffer overflow or input validation vulnerability pattern that has been documented in various security frameworks including CWE-121, which addresses stack-based buffer overflow conditions, and CWE-20, which covers improper input validation scenarios. The vulnerability's classification aligns with ATT&CK technique T1499.004, which describes network denial of service attacks targeting system availability.
The operational impact of this vulnerability extends beyond simple system unavailability as it can severely disrupt business operations within organizations relying on SAP NetWeaver systems. When the Enqueue Server crashes, it affects the entire ABAP platform's ability to manage distributed transactions and maintain system consistency across multiple application servers. The attack requires no authentication credentials or specific system knowledge, making it particularly dangerous as it can be exploited by any network entity with access to the affected system's ports. Organizations may experience significant downtime, loss of productivity, and potential revenue impact during the period when systems remain offline while recovery procedures are implemented.
Mitigation strategies for CVE-2021-27606 should prioritize immediate implementation of SAP security patches released through SAP Note 2959699 and related security advisories. Organizations must ensure proper network segmentation and access controls to limit exposure of SAP systems to untrusted networks, implementing firewalls and access control lists to restrict communication to necessary business partners only. Network monitoring solutions should be deployed to detect anomalous traffic patterns that may indicate exploitation attempts, while regular vulnerability assessments and penetration testing should be conducted to identify similar input validation flaws within the SAP environment. System administrators should also implement robust logging and alerting mechanisms to quickly identify when systems become unresponsive, and establish incident response procedures specifically addressing SAP denial of service scenarios. The vulnerability demonstrates the importance of maintaining up-to-date security patches and the critical need for organizations to implement comprehensive vulnerability management programs that address both known and emerging threats within their SAP infrastructure environments.