CVE-2019-1878 in Telepresence Codec
Summary
by MITRE
A vulnerability in the Cisco Discovery Protocol (CDP) implementation for the Cisco TelePresence Codec (TC) and Collaboration Endpoint (CE) Software could allow an unauthenticated, adjacent attacker to inject arbitrary shell commands that are executed by the device. The vulnerability is due to insufficient input validation of received CDP packets. An attacker could exploit this vulnerability by sending crafted CDP packets to an affected device. A successful exploit could allow the attacker to execute arbitrary shell commands or scripts on the targeted device.
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Analysis
by VulDB Data Team • 10/07/2023
The vulnerability identified as CVE-2019-1878 represents a critical security flaw within the Cisco Discovery Protocol implementation found in Cisco TelePresence Codec and Collaboration Endpoint software versions. This weakness exists in the network discovery mechanism that devices use to communicate with neighboring network equipment, creating an unexpected attack surface that can be exploited by adversaries positioned within the same network segment. The Cisco Discovery Protocol serves as a proprietary protocol that enables network devices to share information about themselves with adjacent devices, but in this case, the implementation fails to properly validate incoming packet data, creating a pathway for malicious command injection.
The technical root cause of this vulnerability stems from inadequate input validation mechanisms within the CDP packet processing code of affected Cisco devices. When these devices receive CDP packets from neighboring network equipment, they fail to properly sanitize or validate the data contained within these packets before processing them. This insufficient validation creates a command injection vulnerability where an attacker can craft malicious CDP packets containing shell commands that get executed by the device's underlying operating system. The vulnerability specifically affects devices running Cisco TelePresence Codec and Collaboration Endpoint software, making them susceptible to exploitation by any attacker who can position themselves within the same broadcast domain or network segment.
The operational impact of this vulnerability extends beyond simple command execution, as it provides attackers with unauthorized access to the targeted devices' command-line interfaces and underlying system resources. An attacker who successfully exploits this vulnerability can execute arbitrary shell commands with the privileges of the device's system user, potentially leading to complete system compromise. This could enable attackers to modify device configurations, install malicious software, exfiltrate sensitive information, or use the compromised device as a pivot point for attacking other systems within the network. The adjacent network attacker requirement means that exploitation does not require network credentials or complex reconnaissance, as the attack can be launched from within the same broadcast domain.
Mitigation strategies for CVE-2019-1878 should focus on both immediate defensive measures and long-term architectural improvements. Organizations should implement network segmentation to limit the broadcast domain scope where CDP packets can be received, effectively reducing the attack surface for this vulnerability. The Cisco recommended solution involves applying the latest software patches that address the input validation issues in CDP packet processing, along with enabling CDP access control features that limit which devices can send CDP information to the affected endpoints. Network administrators should also consider disabling CDP functionality entirely on devices where it is not required, as this eliminates the attack vector entirely. From a security monitoring perspective, organizations should implement network traffic analysis to detect anomalous CDP packet patterns that might indicate exploitation attempts, aligning with ATT&CK technique T1046 for network service scanning and T1059 for command and scripting interpreter usage.
This vulnerability aligns with CWE-77 and CWE-78 categories from the Common Weakness Enumeration, specifically addressing command injection flaws where insufficient input validation leads to arbitrary code execution. The attack vector demonstrates characteristics consistent with the ATT&CK framework's T1059.007 sub-technique for script-based execution, as attackers leverage the device's shell capabilities to execute malicious payloads. The vulnerability also reflects broader security principles from NIST SP 800-53, particularly in the area of input validation controls that should be implemented to prevent injection attacks. Organizations should also consider implementing network access control lists to restrict CDP packet transmission between devices, as this provides an additional layer of defense that aligns with the principle of least privilege and reduces the potential impact of such vulnerabilities in the network infrastructure.