CVE-2019-1683 in IP Phone SPA112
Summary
by MITRE
A vulnerability in the certificate handling component of the Cisco SPA112, SPA525, and SPA5X5 Series IP Phones could allow an unauthenticated, remote attacker to listen to or control some aspects of a Transport Level Security (TLS)-encrypted Session Initiation Protocol (SIP) conversation. The vulnerability is due to the improper validation of server certificates. An attacker could exploit this vulnerability by crafting a malicious server certificate to present to the client. An exploit could allow an attacker to eavesdrop on TLS-encrypted traffic and potentially route or redirect calls initiated by an affected device. Affected software include version 7.6.2 of the Cisco Small Business SPA525 Series IP Phones and Cisco Small Business SPA5X5 Series IP Phones and version 1.4.2 of the Cisco Small Business SPA500 Series IP Phones and Cisco Small Business SPA112 Series IP Phones.
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Analysis
by VulDB Data Team • 07/19/2023
The vulnerability identified as CVE-2019-1683 represents a critical flaw in the certificate validation mechanisms of Cisco Small Business IP phone series, specifically affecting the SPA112, SPA525, and SPA5X5 models. This weakness resides in the certificate handling component that governs how these devices validate server certificates during TLS-encrypted SIP communication sessions. The vulnerability stems from inadequate certificate validation procedures that fail to properly verify the authenticity and integrity of presented certificates, creating a pathway for malicious actors to exploit the trust relationship between the IP phone and its communication endpoints.
The technical exploitation of this vulnerability occurs through man-in-the-middle attack vectors where an unauthenticated remote attacker crafts malicious server certificates designed to deceive the affected IP phones. When these forged certificates are presented to the vulnerable devices, the improper validation logic accepts them as legitimate, thereby establishing a false trust relationship. This allows attackers to intercept, monitor, and potentially manipulate TLS-encrypted SIP conversations that should remain protected. The flaw specifically affects the certificate verification process, which according to CWE-295 - "Improper Certificate Validation" directly undermines the cryptographic security controls designed to protect communication channels.
The operational impact of this vulnerability extends beyond simple eavesdropping capabilities to include potential call manipulation and redirection. Attackers can not only listen to conversations but also route calls to unauthorized destinations, potentially leading to significant financial losses through toll fraud or service disruption. The affected devices operate in enterprise and small business environments where SIP-based voice communications are critical for business operations, making this vulnerability particularly dangerous. According to ATT&CK framework domain T1566 - "Phishing", this vulnerability could be exploited through social engineering campaigns where attackers present convincing but malicious certificates to compromise voice communication systems.
Cisco Small Business SPA525 Series IP Phones running version 7.6.2, along with SPA5X5 Series IP Phones at the same version, and SPA500 Series IP Phones as well as SPA112 Series IP Phones at version 1.4.2 are all affected by this vulnerability. The exploitation requires no authentication credentials from the attacker, making it particularly dangerous as it can be executed remotely without prior access to the network. The vulnerability affects the core security mechanisms that protect VoIP communications, potentially allowing attackers to gain unauthorized access to sensitive business communications and disrupt critical telephony services. Organizations using these affected devices face significant risk of voice data interception and potential service disruption that could impact business continuity and regulatory compliance requirements for secure communications.