CVE-2021-27629 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 EncPSetUnsupported() 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
SAP NetWeaver ABAP Server and ABAP Platform systems running specific kernel versions are vulnerable to a denial of service condition that stems from inadequate input validation within the EncPSetUnsupported() method. This vulnerability affects multiple kernel versions including 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 exists in the Enqueue Server component which is responsible for managing locks and ensuring data consistency in distributed ABAP applications. The vulnerability represents a classic case of improper input validation where the system fails to properly sanitize or validate incoming network packets before processing them within the EncPSetUnsupported() method.
The technical exploitation of this vulnerability occurs when an unauthenticated attacker sends a specially crafted network packet to the affected system. The packet triggers an internal error within the system's processing logic due to the method's inability to handle malformed or unexpected input parameters. When the EncPSetUnsupported() method receives input that falls outside its expected parameter ranges or format specifications, the system's internal error handling mechanism fails, resulting in a system crash. This crash manifests as an application-level failure that renders the entire SAP system unavailable to legitimate users and applications. The vulnerability does not permit data exfiltration or modification since the attack is specifically designed to cause system unavailability rather than to access or alter system resources.
From an operational perspective, this vulnerability presents a significant risk to business continuity and system availability in enterprise environments that rely on SAP NetWeaver platforms. The impact extends beyond simple service disruption as it can affect critical business processes that depend on SAP systems for enterprise resource planning, supply chain management, and financial operations. The attack requires no authentication credentials or specific system knowledge, making it particularly dangerous as it can be exploited by any network entity capable of reaching the target system. The vulnerability's classification aligns with CWE-20, Improper Input Validation, which is a fundamental security weakness that frequently leads to various types of system failures. The attack pattern follows the MITRE ATT&CK framework's technique T1499.004, Network Denial of Service, which specifically addresses attacks that render systems unavailable through network-based methods.
Organizations affected by this vulnerability should implement immediate mitigations including applying the relevant SAP security patches and updates released by SAP to address the input validation issues in the Enqueue Server component. Network segmentation and access controls should be strengthened to limit exposure of SAP systems to untrusted networks, while implementing network monitoring to detect and alert on suspicious packet patterns that may indicate exploitation attempts. System administrators should also consider implementing intrusion detection systems that can identify the specific packet signatures associated with this vulnerability. The remediation process should include thorough testing of patches in non-production environments before deployment to ensure no regression issues occur in critical business applications. Additionally, organizations should review their incident response procedures to ensure rapid containment and recovery capabilities in case of successful exploitation attempts.