CVE-2020-9028 in SyncServer S100
Summary
by MITRE
Symmetricom SyncServer S100 2.90.70.3, S200 1.30, S250 1.25, S300 2.65.0, and S350 2.80.1 devices allow stored XSS via the newUserName parameter on the "User Creation, Deletion and Password Maintenance" screen (when creating a new user).
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Analysis
by VulDB Data Team • 05/12/2025
The vulnerability identified as CVE-2020-9028 affects Symmetricom SyncServer series devices including models S100, S200, S250, S300, and S350 with specific firmware versions. This represents a critical security flaw that enables attackers to execute malicious scripts within the context of a victim's browser session. The vulnerability resides in the web-based administrative interface of these network time synchronization devices, which are widely deployed in enterprise and industrial environments for precise timekeeping and synchronization services. These devices are commonly used in critical infrastructure sectors including telecommunications, financial services, and power grid operations where accurate time synchronization is essential for system integrity and security.
The technical flaw manifests as a stored cross-site scripting vulnerability within the user management functionality of the SyncServer web interface. When administrators or authorized users navigate to the "User Creation, Deletion and Password Maintenance" screen and attempt to create a new user account, the system fails to properly sanitize the newUserName parameter. This parameter is directly incorporated into the web page response without adequate input validation or output encoding, allowing maliciously crafted user names containing script code to be stored within the device's user database. When other users view the list of created users or when the affected user name is rendered in any administrative interface, the embedded malicious script executes in the context of the victim's browser session.
The operational impact of this vulnerability is significant given the critical role these time synchronization devices play in enterprise networks. An attacker who successfully exploits this vulnerability could potentially gain unauthorized access to administrative functions, escalate privileges, or establish persistent access within the network infrastructure. The stored nature of the XSS vulnerability means that the malicious payload remains active even after the initial injection, continuously affecting any user who interacts with the vulnerable interface. This vulnerability also aligns with CWE-79 Cross-site Scripting, which categorizes the flaw as a weakness in input validation and output encoding mechanisms. The attack vector specifically maps to ATT&CK technique T1059.007 Command and Scripting Interpreter: JavaScript, as the exploitation involves executing JavaScript code within the browser context of legitimate users.
Mitigation strategies for this vulnerability should include immediate firmware updates from Symmetricom to address the XSS flaw, along with network segmentation to limit access to the administrative interfaces. Administrators should implement strict input validation policies and output encoding measures to prevent similar issues in custom web applications. Security monitoring should focus on detecting anomalous user creation patterns and unexpected script execution within the administrative interfaces. The vulnerability also underscores the importance of secure coding practices and input sanitization in network device management interfaces, as highlighted by industry standards such as the OWASP Top Ten and NIST cybersecurity guidelines. Organizations should conduct comprehensive vulnerability assessments of their time synchronization infrastructure and implement multi-factor authentication mechanisms to reduce the risk of unauthorized access to administrative functions.