CVE-2019-1980 in Firepower Threat Defense Software
Summary
by MITRE
A vulnerability in the protocol detection component of Cisco Firepower Threat Defense Software, Cisco FirePOWER Services Software for ASA, and Cisco Firepower Management Center Software could allow an unauthenticated, remote attacker to bypass filtering protections. The vulnerability is due to improper detection of the initial use of a protocol on a nonstandard port. An attacker could exploit this vulnerability by sending traffic on a nonstandard port for the protocol in use through an affected device. An exploit could allow the attacker to bypass filtering and deliver malicious requests to protected systems that would otherwise be blocked. Once the initial protocol flow on the nonstandard port is detected, future flows on the nonstandard port will be successfully detected and handled as configured by the applied policy.
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Analysis
by VulDB Data Team • 11/27/2024
The vulnerability identified as CVE-2019-1980 resides within the protocol detection mechanisms of Cisco's security infrastructure products including Firepower Threat Defense Software, FirePOWER Services Software for ASA, and Firepower Management Center Software. This flaw represents a critical weakness in the system's ability to properly identify and classify network traffic based on protocol characteristics, creating a pathway for malicious actors to circumvent established security controls. The vulnerability specifically targets the protocol detection component's handling of initial protocol identification when traffic arrives on nonstandard ports, which fundamentally undermines the integrity of the device's filtering capabilities.
The technical root cause of this vulnerability stems from the improper handling of protocol detection logic when network traffic arrives on nonstandard ports that do not align with expected protocol port mappings. When traffic is transmitted through an affected device on a nonstandard port for a particular protocol, the system fails to correctly identify and classify that initial flow, allowing it to bypass the normal filtering processes that would typically block malicious traffic. This misclassification occurs during the initial protocol detection phase, where the system's protocol detection engine cannot properly recognize the protocol being used when it appears on an unexpected port. The vulnerability is particularly concerning because it affects the fundamental operation of protocol-based filtering, which is a core security function in network defense systems. According to CWE standards, this corresponds to CWE-20: Improper Input Validation, as the system fails to properly validate and classify protocol traffic based on port information. The issue aligns with ATT&CK technique T1071.004: Application Layer Protocol: DNS, where attackers exploit protocol detection weaknesses to bypass network security controls.
The operational impact of this vulnerability is severe and far-reaching, as it enables unauthenticated remote attackers to completely bypass the filtering protections that organizations rely upon to defend their networks. An attacker exploiting this vulnerability can send malicious traffic through affected Cisco devices on nonstandard ports, effectively neutralizing the security controls that would normally block such traffic. Once the initial protocol flow is established on a nonstandard port, the system correctly identifies and handles subsequent traffic on that same port, but the initial bypass allows malicious content to reach protected systems that would otherwise be blocked. This creates a window of opportunity for attackers to deliver payloads, establish command and control connections, or perform other malicious activities that would normally be prevented by the device's security policies. The vulnerability essentially creates a backdoor mechanism that allows attackers to circumvent network security controls without requiring authentication or direct access to the device itself. Organizations using these affected products face significant risk of data breaches, unauthorized access, and network compromise, as the vulnerability allows attackers to bypass fundamental network security protections.
Mitigation strategies for CVE-2019-1980 should focus on immediate remediation through official Cisco software updates and patches that address the protocol detection logic flaw. Organizations must ensure that all affected devices are updated with the latest security patches released by Cisco to correct the improper protocol detection behavior on nonstandard ports. Network administrators should also implement additional monitoring and logging of traffic on nonstandard ports to detect potential exploitation attempts, as the vulnerability may not be immediately apparent through normal security operations. Configuration changes may include enforcing strict port-based filtering rules that prevent traffic on nonstandard ports from bypassing security controls, though this approach requires careful consideration to avoid disrupting legitimate network operations. Organizations should also consider implementing network segmentation and additional security controls beyond the affected devices to provide defense-in-depth. The vulnerability highlights the importance of proper protocol detection and validation in network security systems, emphasizing that protocol identification must be robust enough to handle traffic patterns that deviate from standard port assignments. Additionally, organizations should conduct comprehensive security assessments of their network infrastructure to identify any other potential protocol detection weaknesses that could be exploited in similar manners.