CVE-2018-0279 in NFVIS
Summary
by MITRE
A vulnerability in the Secure Copy Protocol (SCP) server of Cisco Enterprise NFV Infrastructure Software (NFVIS) could allow an authenticated, remote attacker to access the shell of the underlying Linux operating system on the affected device. The vulnerability is due to improper input validation of command arguments. An attacker could exploit this vulnerability by using crafted arguments when opening a connection to the affected device. An exploit could allow the attacker to gain shell access with a non-root user account to the underlying Linux operating system on the affected device. Due to the system design, access to the Linux shell could allow execution of additional attacks that may have a significant impact on the affected system. This vulnerability affects Cisco devices that are running release 3.7.1, 3.6.3, or earlier releases of Cisco Enterprise NFV Infrastructure Software (NFVIS) when access to the SCP server is allowed on the affected device. Cisco NFVIS Releases 3.5.x and 3.6.x do allow access to the SCP server by default, while Cisco NFVIS Release 3.7.1 does not. Cisco Bug IDs: CSCvh25026.
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Analysis
by VulDB Data Team • 02/06/2020
The vulnerability identified as CVE-2018-0279 represents a critical security flaw in Cisco Enterprise NFV Infrastructure Software (NFVIS) that undermines the integrity of the Secure Copy Protocol (SCP) implementation. This issue affects specific versions of the NFVIS platform including releases 3.7.1, 3.6.3, and earlier versions where SCP server functionality remains enabled. The vulnerability stems from inadequate input validation mechanisms within the SCP server component, creating a pathway for malicious actors to escalate their privileges and gain unauthorized access to the underlying Linux operating system. The flaw specifically manifests during the processing of command arguments when establishing SCP connections, allowing attackers to manipulate input parameters to execute unintended system commands.
The technical exploitation of this vulnerability follows a well-defined attack pattern that aligns with common privilege escalation techniques documented in the CWE (Common Weakness Enumeration) catalog under CWE-20, which describes "Improper Input Validation." Attackers can craft specially formatted arguments during SCP connection attempts to bypass normal authentication and authorization checks. This vulnerability operates at the application layer and leverages the trust model inherent in the SCP protocol implementation, where legitimate command arguments are processed without sufficient sanitization. The attack vector requires an authenticated session, meaning that an attacker must first establish valid credentials to the NFVIS device before attempting exploitation, though the resulting access provides a non-root user account with shell privileges that can be leveraged for further system compromise.
The operational impact of this vulnerability extends beyond simple unauthorized access, as the compromised shell environment provides attackers with significant control over the underlying Linux system. This access enables execution of additional attacks that may have cascading effects throughout the network infrastructure, particularly in virtualized environments where NFVIS serves as the foundation for network function virtualization. The vulnerability's potential for escalation is particularly concerning given that the affected system design allows for shell access that could be used to install backdoors, exfiltrate sensitive data, or manipulate network configurations. The impact is amplified by the fact that NFVIS devices often serve as critical infrastructure components in enterprise and service provider networks, making successful exploitation a significant threat to overall network security posture.
Organizations affected by this vulnerability should implement immediate mitigations including disabling SCP server functionality when not required, applying available Cisco security patches, and implementing network segmentation to limit access to affected devices. The vulnerability's classification under ATT&CK framework's privilege escalation techniques highlights the need for comprehensive monitoring of shell access patterns and command execution activities on affected systems. Security teams should also consider implementing additional controls such as multi-factor authentication for administrative access, regular security assessments of NFVIS deployments, and enhanced logging of SCP connection attempts to detect potential exploitation attempts. The vulnerability underscores the importance of proper input validation and secure coding practices in network infrastructure software, particularly in components that handle user-provided data. Organizations should also conduct thorough inventory assessments to identify all instances of affected NFVIS releases and ensure that default configurations are properly enforced to minimize exposure windows.