CVE-2020-3574 in IP Phone
Summary
by MITRE • 11/07/2020
A vulnerability in the TCP packet processing functionality of Cisco IP Phones could allow an unauthenticated, remote attacker to cause the phone to stop responding to incoming calls, drop connected calls, or unexpectedly reload. The vulnerability is due to insufficient TCP ingress packet rate limiting. An attacker could exploit this vulnerability by sending a high and sustained rate of crafted TCP traffic to the targeted device. A successful exploit could allow the attacker to impact operations of the phone or cause the phone to reload, leading to a denial of service (DoS) condition.
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Analysis
by VulDB Data Team • 12/03/2020
This vulnerability affects Cisco IP Phones and represents a significant denial of service risk that can be exploited remotely without authentication. The flaw resides in the TCP packet processing functionality where inadequate ingress rate limiting allows malicious actors to overwhelm the device with crafted TCP traffic. The vulnerability is classified as a weakness in resource management where the phone fails to properly regulate incoming TCP packets, creating a condition that can be easily exploited by attackers with minimal technical expertise. This type of vulnerability aligns with CWE-770, which addresses allocation of resources without proper limits or throttling mechanisms. The attack vector requires only network access to the targeted phone and can be executed through sustained high-rate TCP traffic that exceeds the device's processing capabilities.
The operational impact of this vulnerability extends beyond simple service disruption as it can cause phones to become unresponsive to incoming calls, terminate active connections, or initiate unexpected system reloads. This behavior directly impacts business continuity and communication infrastructure reliability, particularly in environments where IP phone systems are critical for operations. The DoS condition created by this vulnerability can persist until manual intervention occurs or the device automatically recovers, potentially causing significant disruption to voice communications. Organizations relying on Cisco IP Phones for mission-critical communications face substantial risk from this vulnerability, as it can be exploited by attackers to systematically degrade service quality or create complete communication outages.
The exploitation of this vulnerability follows a pattern consistent with network-based DoS attacks that target resource exhaustion or processing limitations in network devices. Attackers can leverage the insufficient rate limiting by flooding the phone with TCP packets at rates that exceed the device's ability to process legitimate traffic, causing the system to become overwhelmed and enter a degraded state. This attack methodology maps to ATT&CK technique T1498, which covers denial of service attacks targeting network infrastructure. The vulnerability is particularly concerning because it requires no authentication credentials and can be executed from remote locations, making it an attractive target for attackers seeking to disrupt communications without requiring physical access or advanced technical skills. Network administrators must consider this vulnerability as part of their overall security posture assessment for voice communication systems.
Mitigation strategies should focus on implementing network-level rate limiting and access control measures to prevent excessive TCP traffic from reaching affected devices. Organizations should consider deploying firewall rules that limit incoming TCP connections or implement TCP rate limiting at network boundaries to protect IP phone systems. Cisco has released software updates addressing this vulnerability, and administrators should prioritize applying these patches to affected devices. Network segmentation can provide additional protection by isolating IP phone systems from general network traffic and limiting potential attack vectors. Monitoring systems should be configured to detect unusual TCP traffic patterns that may indicate exploitation attempts, and baseline performance metrics should be established to quickly identify when devices begin exhibiting abnormal behavior. The implementation of these controls aligns with security best practices for protecting voice over IP infrastructure and reducing the attack surface for network-based DoS attacks.