CVE-2019-20028 in SV8100
Summary
by MITRE
Aspire-derived NEC PBXes operating InMail software, including all versions of SV8100, SV9100, SL1100 and SL2100 devices allow unauthenticated read-only access to voicemails, greetings, and voice response system content through a system's WebPro administration interface.
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Analysis
by VulDB Data Team • 07/30/2020
This vulnerability affects NEC PBX systems running InMail software where devices such as SV8100, SV9100, SL1100, and SL2100 are configured with the WebPro administration interface. The flaw represents a critical security weakness that allows any remote attacker to access sensitive voice messaging content without requiring authentication credentials. The vulnerability exists within the web-based administrative interface implementation, specifically in the access control mechanisms that govern voicemail and voice response system content retrieval. This represents a direct violation of the principle of least privilege and demonstrates a fundamental flaw in the system's authorization model.
The technical exploitation of this vulnerability stems from insufficient input validation and access control checks within the WebPro interface. Attackers can directly access voicemail messages, recorded greetings, and voice response system content by navigating to specific URL endpoints or making unauthenticated API calls to the system. This type of vulnerability maps to CWE-284 which describes improper access control, and more specifically relates to CWE-306 which addresses missing authentication. The flaw essentially creates a backdoor into the voice messaging system that bypasses all normal authentication mechanisms. From an operational perspective, this vulnerability allows attackers to gain complete visibility into the voice communication system without any prior knowledge of user credentials or system access keys.
The impact of this vulnerability extends beyond simple information disclosure as it provides attackers with comprehensive access to potentially sensitive business communications, personal messages, and system configuration details that could be used for further attacks. Voice messages may contain confidential business information, personal data, or strategic communications that could be exploited for social engineering, corporate espionage, or financial fraud. The unauthenticated nature of the access means that any network-connected device with the appropriate network access can exploit this vulnerability, making it particularly dangerous in enterprise environments where PBX systems are often accessible from multiple network segments. This vulnerability aligns with ATT&CK technique T1071.004 which describes application layer protocol usage for data exfiltration, and T1566 which covers credential harvesting through social engineering.
Organizations should immediately implement network segmentation to isolate PBX systems from general network access and ensure that the WebPro interface is not exposed to untrusted networks. The most effective immediate mitigation involves disabling the WebPro administration interface if it is not actively required for system management or implementing strong network-level access controls using firewalls and access control lists. System administrators should also verify that all devices are running the latest firmware versions that contain patches for this vulnerability. Additionally, organizations should conduct comprehensive network scans to identify all affected devices and implement monitoring for suspicious access patterns to the voice messaging system. The vulnerability demonstrates the importance of secure configuration management and the need for regular security assessments of telephony systems that often operate with minimal security scrutiny compared to other network infrastructure components.