CVE-2018-5490 in Clustered Data ONTAP
Summary
by MITRE
Read-Only export policy rules are not correctly enforced in Clustered Data ONTAP 8.3 Release Candidate versions and therefore may allow more than "read-only" access from authenticated SMBv2 and SMBv3 clients. This behavior has been resolved in the GA release. Customers running prior release candidates (RCs) are requested to update their systems to the NetApp Data ONTAP 8.3 GA release.
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Analysis
by VulDB Data Team • 03/13/2020
The vulnerability identified as CVE-2018-5490 represents a critical access control flaw in NetApp Clustered Data ONTAP 8.3 Release Candidate versions that undermines the intended read-only export policy enforcement for SMBv2 and SMBv3 protocols. This security weakness specifically affects authenticated clients attempting to access shared resources through Server Message Block protocols, where the system fails to properly restrict user permissions despite configured read-only policies. The flaw exists in the implementation of export policy enforcement mechanisms within the clustered data management system, creating a scenario where legitimate read-only access controls are bypassed through authenticated connections. Organizations utilizing these release candidate versions face potential unauthorized data manipulation risks as the system grants more extensive access privileges than explicitly permitted by the configured policies.
The technical root cause of this vulnerability stems from improper validation and enforcement of export policy rules within the SMB protocol handling components of Clustered Data ONTAP 8.3. When authenticated SMBv2 and SMBv3 clients connect to the system, the access control mechanisms fail to properly evaluate and enforce the read-only restrictions that should be applied to these connections. This misconfiguration allows authenticated users to potentially perform write operations or other privileged actions that should be restricted under the read-only policy framework. The flaw represents a deviation from standard access control implementation practices and demonstrates inadequate boundary checking within the protocol processing layers. The vulnerability specifically impacts the authorization decision-making process where the system should enforce strict read-only access but instead permits expanded privileges through the authenticated connection channels.
The operational impact of CVE-2018-5490 extends beyond simple data integrity concerns to encompass potential data modification, deletion, and unauthorized access to sensitive information within the clustered storage environment. Organizations running affected release candidate versions face increased risk of data compromise as authenticated users can bypass intended read-only restrictions, potentially leading to unauthorized data manipulation or exposure of confidential information. This vulnerability particularly affects enterprise environments where strict access controls are essential for compliance with data protection regulations and internal security policies. The risk is amplified in multi-user environments where multiple authenticated users may attempt to access shared resources under read-only policies, creating potential for unauthorized data changes that could go undetected. Security administrators must consider the potential for privilege escalation and unauthorized data access when evaluating the operational implications of this flaw.
Organizations affected by CVE-2018-5490 should immediately implement the recommended mitigation strategy of upgrading to the NetApp Data ONTAP 8.3 General Availability release, which contains the corrected export policy enforcement mechanisms. This upgrade represents the primary remediation approach as it addresses the root cause of the access control bypass through updated protocol handling and policy enforcement components. The vulnerability aligns with CWE-284 Access Control Issues, specifically addressing improper access control enforcement where the system fails to properly validate user privileges against configured policies. From an ATT&CK framework perspective, this vulnerability maps to T1078 Valid Accounts and T1566 Phishing, as it allows authenticated users to potentially escalate privileges beyond their intended access levels. Organizations should also consider implementing additional monitoring and logging controls to detect unauthorized access attempts or privilege escalation activities that may occur during the interim period before full remediation. The patching process should be prioritized as part of the overall vulnerability management program to prevent exploitation of this access control weakness in production environments.