CVE-2018-8926 in Photo Station
Summary
by MITRE
Permissive regular expression vulnerability in synophoto_dsm_user in Synology Photo Station before 6.8.5-3471 and before 6.3-2975 allows remote authenticated users to conduct privilege escalation attacks via the fullname parameter.
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Analysis
by VulDB Data Team • 03/22/2023
The vulnerability identified as CVE-2018-8926 represents a critical permissive regular expression flaw within Synology Photo Station's authentication mechanism, specifically affecting versions prior to 6.8.5-3471 and 6.3-2975. This issue resides in the synophoto_dsm_user component which handles user authentication and privilege management. The flaw manifests when processing the fullname parameter, which is typically used during user registration and profile updates. The vulnerability stems from insufficient input validation that fails to properly sanitize user-supplied data, creating an avenue for malicious exploitation.
The technical implementation of this vulnerability involves a regular expression pattern that is overly permissive in its matching criteria, allowing specially crafted input to bypass intended security checks. Attackers can manipulate the fullname parameter to include malicious payloads that exploit the weak validation logic. This flaw operates under CWE-20, which catalogs improper input validation as a fundamental weakness in software security. The vulnerability enables authenticated users to escalate their privileges by exploiting the insufficient sanitization of user input, potentially allowing them to gain administrative rights or access restricted functionality within the Photo Station application.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it can lead to complete system compromise when combined with other attack vectors. Remote authenticated users can leverage this flaw to manipulate user accounts, potentially gaining access to sensitive photo collections, system configuration settings, and user data. The attack surface includes not only the Photo Station application itself but also potential cascading effects on the broader Synology DSM platform. According to ATT&CK framework, this vulnerability maps to privilege escalation techniques under the T1068 category, specifically targeting the exploitation of application-level weaknesses to elevate user privileges.
Mitigation strategies for CVE-2018-8926 require immediate patching of affected Synology Photo Station versions to the recommended secure releases. Organizations should implement comprehensive input validation measures that enforce strict sanitization of all user-supplied parameters, particularly those used in authentication contexts. Network segmentation and access controls should be enhanced to limit the potential impact of successful exploitation attempts. Security monitoring should include detection of unusual authentication patterns and privilege escalation activities. The vulnerability highlights the importance of proper regular expression design and input validation practices, emphasizing that security by design principles must be applied to all user-facing application components. Additionally, organizations should conduct thorough security assessments of their Synology DSM environments to identify and remediate similar vulnerabilities in other components of the platform.