CVE-2019-14656 in Phone
Summary
by MITRE
Yealink phones through 2019-08-04 do not properly check user roles in POST requests. Consequently, the default User account (with a password of user) can make admin requests via HTTP.
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Analysis
by VulDB Data Team • 01/05/2024
The vulnerability identified as CVE-2019-14656 affects Yealink IP phones with firmware released prior to August 4, 2019, representing a critical authorization flaw that undermines the security model of these communication devices. This issue stems from insufficient validation of user permissions within the web-based administration interface of the phones, specifically in the handling of POST HTTP requests that are typically used for administrative operations. The flaw allows any user with access to the device's web interface to escalate their privileges and execute administrative functions without proper authentication, effectively bypassing the intended security boundaries that separate standard user accounts from administrative ones.
The technical nature of this vulnerability aligns with CWE-285, which addresses improper authorization issues in software systems. The root cause occurs when the phone's web server fails to verify the role or permissions of the user making the POST request before executing administrative commands. This misconfiguration creates a path for privilege escalation where the default user account, which typically has minimal access rights, can manipulate the system through HTTP POST requests that should only be executable by administrators. The vulnerability is particularly concerning because it affects the authentication and authorization mechanisms that are fundamental to securing networked devices and preventing unauthorized access to critical system functions.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it enables attackers to perform a wide range of administrative actions including configuration changes, firmware updates, user management, and potentially network modifications that could compromise the entire communication infrastructure. Attackers could leverage this weakness to gain persistent access to the phone systems, monitor communications, redirect calls, or even use the devices as entry points for broader network attacks. This vulnerability directly relates to several tactics in the MITRE ATT&CK framework under the Privilege Escalation and Defense Evasion categories, where adversaries can exploit weak access controls to maintain long-term presence within networks and avoid detection through legitimate administrative access.
Organizations utilizing Yealink phones should immediately implement mitigations including updating firmware to versions released after August 4, 2019, which contain proper authorization checks for POST requests. Network segmentation should be implemented to isolate these devices from critical systems and limit their access to essential services only. Additionally, administrators should disable unnecessary web interfaces, enforce strong password policies for default accounts, and monitor network traffic for unusual POST requests that may indicate exploitation attempts. The vulnerability demonstrates the importance of proper input validation and authorization checks in embedded systems, where insufficient security controls can create persistent backdoors that remain exploitable for extended periods. Regular security assessments and firmware updates are essential to prevent similar issues in other networked devices and maintain overall security posture.