CVE-2019-20029 in SV8100
Summary
by MITRE
An exploitable privilege escalation vulnerability exists in the WebPro functionality of Aspire-derived NEC PBXes, including all versions of SV8100, SV9100, SL1100 and SL2100 devices. A specially crafted HTTP POST can cause privilege escalation resulting in a higher privileged account, including an undocumented developer level of access.
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Analysis
by VulDB Data Team • 07/30/2020
The vulnerability identified as CVE-2019-20029 represents a critical privilege escalation flaw within the web-based administration interface of NEC PBX systems derived from the Aspire platform. This vulnerability specifically affects several models including the SV8100, SV9100, SL1100, and SL2100 series devices, which are widely deployed in enterprise communication environments. The flaw resides in the WebPro functionality component that handles web-based administrative tasks, making it accessible to remote attackers who can exploit this weakness without requiring authentication. The vulnerability's severity is amplified by its ability to grant unauthorized access to developer-level privileges, which typically remain hidden from normal administrative interfaces and provide extensive control over system configuration and potentially sensitive data.
The technical implementation of this privilege escalation vulnerability stems from inadequate input validation and access control mechanisms within the WebPro component of these PBX systems. Attackers can exploit this weakness by crafting a specially formatted HTTP POST request that manipulates the authentication and authorization flow within the system. This particular attack vector allows an unauthenticated or low-privileged user to escalate their access rights to include developer-level permissions, which normally require specific authorization tokens or administrative credentials. The flaw essentially bypasses the intended access control boundaries by not properly validating the user's privileges before processing certain administrative functions, creating a pathway for unauthorized privilege elevation.
The operational impact of CVE-2019-20029 extends beyond simple unauthorized access, as the developer-level privileges gained through this vulnerability provide attackers with extensive control over the PBX system's core functionalities. This elevated access level typically includes capabilities such as system configuration changes, user management, call routing modifications, and potentially access to sensitive telephony data. Organizations utilizing these affected NEC PBX systems face significant risks including unauthorized surveillance, call interception, system disruption, and potential data breaches that could compromise entire communication infrastructures. The vulnerability's exploitation can result in complete system compromise and persistent access, making it particularly dangerous for enterprise environments where these devices often serve as critical communication backbone components.
Security mitigations for this vulnerability should prioritize immediate firmware updates from NEC to address the underlying privilege escalation flaw in the WebPro functionality. Organizations must also implement network segmentation to limit access to these administrative interfaces, ensuring that only trusted administrative workstations can reach the affected ports and services. Additional protective measures include disabling unnecessary web administration features when not required, implementing strong access controls with multi-factor authentication, and conducting regular security audits of administrative interfaces. From a defensive perspective, this vulnerability aligns with CWE-284 (Improper Access Control) and may be categorized under ATT&CK technique T1068 (Exploitation for Privilege Escalation), emphasizing the need for robust access control mechanisms and proper input validation in web-based administrative interfaces. Network monitoring should be enhanced to detect unusual HTTP POST requests targeting administrative interfaces, and security teams should implement continuous vulnerability assessment programs to identify similar weaknesses in other networked devices and systems.