CVE-2021-1273 in SD-WAN
Summary
by MITRE • 01/21/2021
Multiple vulnerabilities in Cisco SD-WAN products could allow an unauthenticated, remote attacker to execute denial of service (DoS) attacks against an affected device. For more information about these vulnerabilities, see the Details section of this advisory.
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Analysis
by VulDB Data Team • 02/18/2021
Cisco SD-WAN products contain multiple vulnerabilities that collectively create a significant attack surface for unauthenticated remote exploitation leading to denial of service conditions. These vulnerabilities affect the centralized management and edge devices within Cisco's SD-WAN architecture, which are designed to provide secure network connectivity and traffic optimization across distributed enterprise environments. The affected systems include the Cisco SD-WAN Manager and VNF (Virtual Network Function) appliances that handle critical network operations and traffic routing. The vulnerabilities stem from improper input validation and insufficient access controls within the web-based management interfaces of these devices, creating pathways for attackers to manipulate system resources without requiring authentication credentials. This class of vulnerability aligns with CWE-20, which describes improper input validation, and CWE-287, which addresses improper authentication mechanisms. The attack vectors typically involve sending malformed requests or exploiting buffer overflow conditions in the web servers that handle management communications, allowing attackers to consume system resources or cause application crashes that result in service disruption.
The operational impact of these vulnerabilities extends beyond simple service interruption to potentially compromise the entire SD-WAN infrastructure, affecting thousands of connected endpoints and network segments. When exploited, these vulnerabilities can cause complete service outages for SD-WAN devices, forcing network administrators to manually restart services or replace affected hardware. The distributed nature of SD-WAN deployments means that a single compromised device can impact connectivity across multiple geographical locations, creating cascading failures that may require extensive network reconfiguration. Organizations relying on these devices for critical business operations face significant risk of extended downtime, service degradation, and potential data loss during attack windows. The vulnerabilities are particularly concerning because they operate at the network infrastructure level, affecting core connectivity services rather than application-level functions. Attackers can leverage these weaknesses to create persistent DoS conditions that may require system reinstallation or extended maintenance windows to resolve completely. The exploitation process typically involves sending specially crafted HTTP requests or manipulating API endpoints that lack proper input sanitization, leading to resource exhaustion or application instability.
Mitigation strategies for these vulnerabilities should include immediate deployment of Cisco's security patches and firmware updates, which address the root causes through proper input validation and access control improvements. Network segmentation and firewall rule implementation can help limit exposure by restricting access to management interfaces from trusted networks only, while also implementing monitoring solutions to detect anomalous traffic patterns that may indicate exploitation attempts. Organizations should also consider disabling unnecessary services and interfaces, particularly those that expose management functions to external networks. The implementation of intrusion detection systems with signature-based detection for known exploit patterns can provide early warning capabilities. Additionally, regular security assessments and vulnerability scanning should be conducted to identify any remaining exposure points within the SD-WAN ecosystem. Configuration hardening practices should be enforced, including disabling default accounts, implementing strong access controls, and regularly reviewing access permissions. The ATT&CK framework categorizes these vulnerabilities under the T1499 sub-technique for Network Denial of Service, which specifically addresses attacks targeting network infrastructure components to disrupt service availability. Organizations should also implement incident response procedures that include rapid identification, containment, and recovery protocols specifically designed for SD-WAN infrastructure, ensuring minimal disruption to business operations during remediation activities.