CVE-2020-16262 in Winston
Summary
by MITRE • 10/29/2020
Winston 1.5.4 devices have a local www-data user that is overly permissioned, resulting in root privilege escalation.
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Analysis
by VulDB Data Team • 11/30/2020
The vulnerability identified as CVE-2020-16262 affects Winston 1.5.4 devices where the www-data user possesses excessive permissions that enable unauthorized privilege escalation to root level access. This represents a critical security flaw in the device's user permission model and access control mechanisms. The issue stems from improper privilege separation within the device's operating system configuration, where the web server user account lacks appropriate restrictions that would normally prevent escalation to administrative privileges. The vulnerability specifically targets the local user account management system and demonstrates a failure in implementing the principle of least privilege that is fundamental to secure system design.
This technical flaw operates through a privilege escalation vector that allows the www-data user to gain elevated system permissions through a combination of misconfigured file permissions, inadequate user group memberships, and potentially flawed service execution contexts. The vulnerability is classified as a local privilege escalation issue that leverages the inherent permissions assigned to the web server user account. According to CWE classification, this maps to CWE-276: Improper Ownership, which addresses improper permissions and ownership of system resources, and CWE-732: Incorrect Permission Assignment for Critical Resources, which directly relates to the insecure assignment of system privileges to user accounts. The vulnerability exploits the lack of proper access control enforcement mechanisms that should normally prevent a standard web server user from accessing system-level resources that would enable root privilege escalation.
The operational impact of this vulnerability is severe and potentially catastrophic for affected systems. An attacker who gains access to the www-data user account could leverage this privilege escalation to obtain full root access to the device, enabling complete system compromise, data exfiltration, unauthorized modifications to system configurations, and potential use as a pivot point for attacking other systems within the network. The vulnerability affects devices running Winston 1.5.4 software where the web server component is active and accessible. This creates a significant risk for network infrastructure devices, IoT systems, and embedded platforms that rely on web-based management interfaces. The exploitation of this vulnerability aligns with ATT&CK technique T1068: Exploitation for Privilege Escalation, which involves using vulnerabilities to gain elevated privileges, and T1548.001: Abuse of Functionality, which covers using legitimate system functionality to gain unauthorized access.
Mitigation strategies for CVE-2020-16262 should focus on immediate privilege adjustment and access control hardening. System administrators must review and restrict the permissions assigned to the www-data user account, ensuring that it operates with minimal required privileges. This includes implementing proper user group memberships, restricting file and directory permissions, and ensuring that web server processes do not have unnecessary access to system-critical resources. The device software should be updated to a patched version that addresses the privilege escalation flaw, and proper access control policies should be enforced using mechanisms such as SELinux or AppArmor. Network segmentation and monitoring should be implemented to detect unauthorized access attempts, and regular security audits should be conducted to identify and remediate similar privilege escalation vulnerabilities. Additionally, implementing the principle of least privilege should be enforced across all system accounts and services to prevent similar issues from occurring in the future.