CVE-2021-21559 in NetWorker
Summary
by MITRE • 06/09/2021
Dell EMC NetWorker, versions 18.x, 19.1.x, 19.2.x 19.3.x, 19.4, and 19.4.0.1 contain an Improper Certificate Validation vulnerability in the client (NetWorker Management Console) components which uses SSL encrypted connection in order to communicate with the application server. An unauthenticated attacker in the same network collision domain as the NetWorker Management Console client could potentially exploit this vulnerability to perform man-in-the-middle attacks to intercept and tamper the traffic between the client and the application server.
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Analysis
by VulDB Data Team • 06/11/2021
The vulnerability identified as CVE-2021-21559 affects Dell EMC NetWorker management console components across multiple version lines including 18.x, 19.1.x, 19.2.x, 19.3.x, 19.4, and 19.4.0.1. This represents a critical security flaw in the SSL/TLS certificate validation mechanism that governs communications between client endpoints and application servers. The issue stems from insufficient validation of SSL certificates during the establishment of encrypted connections, creating a pathway for malicious actors to exploit the trust relationship that should exist between legitimate clients and servers.
The technical flaw manifests as improper certificate validation within the client-side components of the NetWorker Management Console, specifically in how SSL/TLS handshakes are processed and validated. This vulnerability operates under CWE-295 which classifies improper certificate validation as a fundamental weakness in cryptographic systems. The flaw allows an attacker positioned within the same network collision domain to perform man-in-the-middle attacks by intercepting and modifying traffic without detection. The vulnerability is particularly concerning because it affects the core authentication and encryption mechanisms that protect sensitive data exchanges between client and server components.
From an operational perspective, this vulnerability creates significant risk for organizations relying on Dell EMC NetWorker for backup and recovery operations. The attack surface is limited to network domains where the attacker can position themselves within the same collision domain as the management console client, but this constraint does not diminish the severity of potential impacts. An attacker could intercept backup data transfers, modify backup configurations, or potentially gain unauthorized access to backup repositories, leading to data loss, system compromise, or service disruption. The unauthenticated nature of the attack means that no credentials or prior access are required to exploit the vulnerability, making it particularly dangerous in environments where network segmentation is insufficient.
The security implications extend beyond simple traffic interception, as this vulnerability could enable attackers to manipulate backup operations, potentially leading to data corruption or complete backup system compromise. Organizations utilizing Dell EMC NetWorker in production environments face substantial risk of data exposure and operational disruption. The vulnerability aligns with ATT&CK technique T1046 which covers network service scanning, and T1566 which covers credential harvesting through social engineering or network attacks. Mitigation strategies should include immediate patching of affected systems, network segmentation to isolate management console components, and implementation of additional monitoring controls to detect anomalous traffic patterns or certificate validation failures. Organizations should also consider implementing certificate pinning mechanisms and regular security assessments to prevent exploitation of similar validation weaknesses in their infrastructure.
This vulnerability represents a classic example of how insufficient cryptographic validation can undermine entire security architectures, particularly in backup and recovery systems where data integrity and confidentiality are paramount. The impact on enterprise security operations extends beyond immediate data compromise to potential long-term operational disruption and regulatory compliance violations. Organizations should prioritize remediation efforts and conduct comprehensive security audits to identify and address similar certificate validation issues in other network components and applications.