CVE-2019-14935 in Phone 15
Summary
by MITRE
3CX Phone 15 on Windows has insecure permissions on the "%PROGRAMDATA%\3CXPhone for Windows\PhoneApp" installation directory, allowing Full Control access for Everyone, and leading to privilege escalation because of a StartUp link.
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Analysis
by VulDB Data Team • 11/23/2023
The vulnerability identified as CVE-2019-14935 affects 3CX Phone 15 on Windows systems, presenting a critical security flaw through improper access control permissions within the application's installation directory. This weakness creates an insecure configuration where the "%PROGRAMDATA%\3CXPhone for Windows\PhoneApp" directory grants Full Control access to all users, including unprivileged accounts. The vulnerability stems from the application's installation process failing to properly set restrictive permissions on its core directory structure, creating a persistent security risk that can be exploited by malicious actors. The issue is particularly concerning because it allows any local user to gain elevated privileges through manipulation of the startup link mechanism, fundamentally undermining the system's security model and user access controls.
The technical exploitation of this vulnerability occurs through the manipulation of the startup link functionality within the 3CX Phone application. When the application is installed with insecure permissions, an attacker can modify or replace executable files within the PhoneApp directory, effectively gaining the ability to execute arbitrary code with the privileges of the target user. This creates a privilege escalation vector where a low-privilege user can elevate their access level to that of a higher-privileged account or even system administrator. The vulnerability is classified under CWE-276 as Insecure Permissions for a Resource, which specifically addresses the lack of proper access control mechanisms that allow unauthorized users to modify critical system components. The startup link component represents a particularly dangerous aspect of this vulnerability since it provides persistent access to the system through legitimate application execution paths.
The operational impact of CVE-2019-14935 extends beyond simple privilege escalation, as it creates persistent backdoor opportunities for attackers who gain access to the system. Once an attacker successfully exploits this vulnerability, they can maintain long-term access to the compromised system through the modified startup link, effectively creating a foothold that survives system reboots and user logoffs. This persistent access capability aligns with the tactics described in the MITRE ATT&CK framework under T1068 for Local Privilege Escalation and T1037 for Boot or Logon Autostart Execution, demonstrating how this vulnerability can be leveraged to establish and maintain persistent access within an organization's network. The vulnerability affects the integrity and confidentiality of the system, as attackers can modify application behavior, intercept communications, or establish further attack vectors through the elevated privileges gained.
Mitigation strategies for CVE-2019-14935 should focus on immediate permission remediation and long-term system hardening measures. Organizations should immediately correct the directory permissions on the "%PROGRAMDATA%\3CXPhone for Windows\PhoneApp" directory to restrict access to only authorized users and system processes. The recommended approach involves implementing proper access control lists that limit write permissions to administrators only while maintaining necessary read access for the application to function. Security administrators should also implement regular permission audits to detect and prevent similar issues in other applications. The vulnerability highlights the importance of proper application installation practices and the need for security awareness during software deployment. Additionally, implementing application whitelisting policies and monitoring for unauthorized modifications to system directories can provide additional defense layers against exploitation attempts. Organizations should also consider implementing principle of least privilege access controls and regular security assessments to identify and remediate similar permission-related vulnerabilities across their infrastructure.