CVE-2021-27607 in NetWeaver ABAP Server
Summary
by MITRE • 06/09/2021
SAP NetWeaver ABAP Server and ABAP Platform (Dispatcher), versions - KRNL32NUC - 7.22,7.22EXT, KRNL32UC - 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 - 7.22,8.04,7.49,7.53,7.73,7.77,7.81,7.82,7.83, 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 ThSncIn() 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 through improper input validation in the ThSncIn() method. This vulnerability affects multiple kernel variants including KRNL32NUC, KRNL32UC, KRNL64NUC, KRNL64UC, and KERNEL across various version releases such as 7.22, 7.22EXT, 7.49, 8.04, 7.53, 7.73, 7.77, 7.81, 7.82, and 7.83. The flaw resides in the dispatcher component's handling of network packets, specifically within the Secure Network Communication processing logic that manages SNC (Secure Network Communication) parameters.
The technical implementation of this vulnerability stems from inadequate validation of input parameters within the ThSncIn() method which processes secure network communication requests. An unauthenticated attacker can exploit this weakness by transmitting a specially crafted network packet that triggers an internal system error. The improper input validation causes the system to enter an unstable state where the dispatcher process fails and terminates, resulting in complete system unavailability. This represents a classic denial of service vulnerability where the attack does not require any authentication credentials or system-specific knowledge to execute successfully.
The operational impact of CVE-2021-27607 is significant as it allows remote attackers to render SAP NetWeaver systems completely unavailable without access to any system data or functionality. The vulnerability affects the core dispatcher functionality which is essential for system operation, making the service disruption potentially catastrophic for business operations. Organizations relying on these systems for critical business processes face substantial risk of operational downtime that could result in financial losses, compliance violations, and disruption of business continuity. The vulnerability's remote exploitability without authentication makes it particularly dangerous as attackers can target systems from anywhere on the network.
Mitigation strategies should focus on applying the relevant SAP security patches and updates immediately, as SAP has released fixes for this vulnerability. Organizations should also implement network segmentation to limit access to SAP systems, deploy intrusion detection systems to monitor for suspicious network traffic patterns, and consider implementing additional monitoring for dispatcher process stability. The vulnerability aligns with CWE-20 (Improper Input Validation) and falls under ATT&CK technique T1499.004 (Endpoint Denial of Service) in the enterprise attack framework. System administrators should also conduct thorough vulnerability assessments to identify all affected systems and ensure proper patch management procedures are in place to prevent similar issues in the future.