CVE-2017-16773 in Universal Search
Summary
by MITRE
Improper authorization vulnerability in Highlight Preview in Synology Universal Search before 1.0.5-0135 allows remote authenticated users to bypass permission checks for directories in POSIX mode.
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Analysis
by VulDB Data Team • 04/03/2023
The CVE-2017-16773 vulnerability represents a critical improper authorization flaw within Synology's Universal Search functionality, specifically affecting the Highlight Preview component. This security weakness exists in versions prior to 1.0.5-0135 and fundamentally undermines the permission model that governs directory access within Synology's file systems. The vulnerability manifests when the system fails to properly validate user permissions during directory access operations, creating a scenario where authenticated users can bypass intended access controls and gain unauthorized visibility into directories they should not be permitted to access.
The technical implementation of this flaw occurs within the POSIX mode directory handling mechanisms of Synology's Universal Search system. When users perform searches or preview operations within the system, the Highlight Preview feature should enforce strict permission checks to ensure that only authorized users can view directory contents. However, the vulnerability allows malicious authenticated users to manipulate the authorization flow, effectively circumventing these checks. This improper authorization issue stems from inadequate validation of user credentials and access rights during the preview process, particularly when dealing with directory structures that are configured with specific POSIX permissions. The flaw operates at the application level where access control decisions are made, rather than at the operating system level, making it particularly insidious as it exploits the application's own permission enforcement mechanisms.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with unauthorized access to potentially sensitive directory structures and their contents. Remote authenticated users who exploit this vulnerability can access directories that are normally restricted to specific user groups or administrative personnel, potentially exposing confidential data, system configurations, or personal files. This unauthorized access capability can be leveraged for further exploitation activities including data exfiltration, privilege escalation attempts, or as a reconnaissance step for more sophisticated attacks. The vulnerability affects the core file system access controls within Synology's Universal Search, which means that any directory or file that is normally protected by POSIX permissions can be accessed by users who should not have such privileges, fundamentally undermining the security posture of the entire system.
Organizations utilizing Synology products with Universal Search functionality must implement immediate remediation measures to address this vulnerability. The primary mitigation involves upgrading to version 1.0.5-0135 or later, which contains the necessary patches to properly enforce authorization checks within the Highlight Preview component. System administrators should conduct thorough vulnerability assessments to identify all affected Synology devices and ensure comprehensive patch deployment across their infrastructure. Additionally, implementing network segmentation and access control measures can help limit the potential impact if exploitation occurs, while monitoring for suspicious access patterns can aid in detecting unauthorized attempts to leverage this vulnerability. Security teams should also consider implementing additional logging and audit mechanisms to track directory access attempts and identify potential exploitation attempts. This vulnerability aligns with CWE-285, which addresses improper authorization issues in software systems, and may be categorized under ATT&CK technique T1078 for valid accounts and T1046 for network service scanning, as attackers could use this vulnerability to expand their access within a compromised environment.