CVE-2018-15387 in SD-WAN Solution
Summary
by MITRE
A vulnerability in the Cisco SD-WAN Solution could allow an unauthenticated, remote attacker to bypass certificate validation on an affected device. The vulnerability is due to improper certificate validation. An attacker could exploit this vulnerability by supplying a system image signed with a crafted certificate to an affected device, bypassing the certificate validation. An exploit could allow an attacker to deploy a crafted system image.
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Analysis
by VulDB Data Team • 03/30/2020
The vulnerability identified as CVE-2018-15387 affects the Cisco SD-WAN Solution, a network infrastructure component designed to manage and optimize wide area network connections. This weakness represents a critical security flaw in the device's certificate validation mechanism that could be exploited by remote attackers without requiring authentication credentials. The vulnerability stems from improper certificate validation procedures within the affected Cisco SD-WAN devices, which are commonly deployed in enterprise environments to manage network traffic and ensure secure communications across distributed networks. The flaw specifically impacts the system's ability to verify the authenticity and integrity of software images before installation, creating a pathway for malicious actors to compromise the device's security posture.
The technical implementation of this vulnerability lies in the device's failure to properly validate digital certificates during the system image deployment process. When a system image is presented to an affected device, the certificate validation mechanism should verify that the image was signed by a legitimate authority and that the signature is valid. However, due to the improper validation logic, an attacker can craft a malicious certificate that appears legitimate to the device's validation system. This allows the attacker to sign a malicious system image with the forged certificate, effectively bypassing the security controls that would normally prevent unauthorized software deployment. The vulnerability falls under CWE-311, which specifically addresses the absence of encryption of sensitive data, as the certificate validation failure creates an opportunity for unauthorized code execution through the software deployment channel.
The operational impact of this vulnerability is severe and far-reaching for organizations utilizing Cisco SD-WAN solutions. An attacker who successfully exploits this vulnerability could gain complete control over the affected device, potentially leading to network disruption, data exfiltration, or the establishment of persistent access points within the network infrastructure. The ability to deploy crafted system images means that attackers could install backdoors, modify network configurations, or introduce malware that operates at the network level. This represents a significant escalation from typical network attacks, as the attacker can fundamentally alter the device's behavior and potentially compromise the entire SD-WAN infrastructure. The vulnerability also aligns with ATT&CK technique T1059, which covers command and scripting interpreter, as the compromised device could be used to execute malicious commands or scripts.
Organizations should implement immediate mitigation strategies to address this vulnerability, including applying the latest security patches provided by Cisco, which typically involve updating the device firmware to correct the certificate validation logic. Network segmentation and monitoring should be enhanced to detect unauthorized system image deployments, as this vulnerability could be used to install malicious software without traditional authentication requirements. The implementation of network access controls and firewall rules that restrict communication with potentially compromised devices can help contain the impact of exploitation attempts. Additionally, organizations should conduct thorough network audits to identify all affected Cisco SD-WAN devices and ensure that proper certificate management procedures are in place to prevent unauthorized software deployment. Security teams should also consider implementing integrity monitoring solutions that can detect changes to system images or certificate stores, providing early warning capabilities for potential exploitation attempts.