CVE-2020-3305 in ASA
Summary
by MITRE
A vulnerability in the implementation of the Border Gateway Protocol (BGP) module in Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition. The vulnerability is due to incorrect processing of certain BGP packets. An attacker could exploit this vulnerability by sending a crafted BGP packet. A successful exploit could allow the attacker to cause a DoS condition on the affected device.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 10/15/2020
The vulnerability identified as CVE-2020-3305 represents a critical weakness in the Border Gateway Protocol implementation within Cisco Adaptive Security Appliance and Cisco Firepower Threat Defense software platforms. This flaw exists in the handling of specific BGP packet structures that are fundamental to internet routing operations and network connectivity. The issue manifests as an improper validation mechanism that fails to correctly process malformed or specially crafted BGP messages, creating a pathway for malicious actors to disrupt network operations through remote exploitation without requiring authentication credentials.
The technical root cause of this vulnerability stems from inadequate input validation within the BGP module's packet processing logic. When the affected Cisco devices receive specially crafted BGP packets containing malformed attributes or unexpected packet structures, the software fails to properly handle these inputs and subsequently crashes or becomes unresponsive. This processing failure occurs at the protocol level where BGP messages are parsed and validated, creating a condition where legitimate network traffic can be disrupted by maliciously constructed packets that exploit the software's insufficient error handling mechanisms. The vulnerability specifically affects the BGP update message processing functionality and can be triggered through various packet composition patterns that bypass normal validation checks.
From an operational perspective, this vulnerability presents a significant risk to network infrastructure reliability and availability. A successful exploitation of CVE-2020-3305 can result in complete denial of service conditions where the affected ASA or FTD devices become unavailable, disrupting all network traffic passing through them. The impact extends beyond simple service interruption as it affects the core routing functionality of the network, potentially causing cascading failures across connected networks that depend on proper BGP routing information exchange. Organizations relying on these security appliances for network protection face the risk of extended downtime, service disruption, and potential loss of network connectivity for critical business operations.
The attack surface for this vulnerability is particularly concerning given that BGP is a fundamental protocol for internet routing and the exploitation can occur remotely without authentication requirements. This aligns with ATT&CK technique T1499.004 for network denial of service attacks and represents a specific implementation weakness that could be leveraged by threat actors to disrupt critical network infrastructure. Security professionals should note that this vulnerability falls under CWE-248, representing an improper exception handling scenario where the software does not properly manage unexpected input conditions. Organizations should implement immediate mitigation strategies including applying the relevant Cisco security patches, configuring BGP filtering rules to restrict incoming packets, and implementing network segmentation to limit the potential impact of such attacks. The vulnerability demonstrates the critical importance of robust input validation in network security appliances and the potential for protocol-level flaws to create widespread service disruption.