CVE-2017-7199 in Nessus
Summary
by MITRE
Nessus 6.6.2 - 6.10.3 contains a flaw related to insecure permissions that may allow a local attacker to escalate privileges when the software is running in Agent Mode. Version 6.10.4 fixes this issue.
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Analysis
by VulDB Data Team • 03/24/2017
The vulnerability identified as CVE-2017-7199 affects Tenable Nessus versions ranging from 6.6.2 through 6.10.3 when operating in Agent Mode. This flaw represents a significant security weakness that stems from improper file and directory permissions within the Nessus software implementation. The issue specifically impacts systems where Nessus operates in agent mode, which is a configuration where the Nessus agent runs on target systems to perform scans rather than relying on a centralized server approach. The insecure permission settings create an exploitable condition that allows local attackers to potentially escalate their privileges to higher system levels. This vulnerability is particularly concerning because it operates at the local system level, meaning an attacker who already has access to the system but with limited privileges could leverage this flaw to gain elevated access. The flaw resides in the way Nessus handles file permissions during its operation in agent mode, creating opportunities for privilege escalation through manipulation of system resources that should normally be protected from unauthorized access. This represents a classic case of insufficient privilege separation and inadequate access control mechanisms within the software's file system interactions.
The technical implementation of this vulnerability manifests through improper file permission handling within the Nessus agent software. When Nessus operates in agent mode, it creates and manages various temporary files, configuration data, and system resources that require appropriate access controls. The flaw occurs because certain critical files or directories are created with permissions that allow unauthorized local users to modify or access these resources. This typically involves the creation of files with world-writable permissions or inadequate ownership controls that enable privilege escalation attacks. Attackers can exploit this by placing malicious code or modifying existing files in these improperly protected locations, allowing them to execute code with elevated privileges. The vulnerability demonstrates poor adherence to security best practices regarding file system access control and privilege management. From a cybersecurity perspective, this vulnerability aligns with CWE-276, which describes improper file permissions, and represents a direct violation of the principle of least privilege. The flaw essentially creates a backdoor mechanism within the software's own file system operations that bypasses normal security controls, making it particularly dangerous for systems where Nessus agents are deployed with elevated privileges.
The operational impact of this vulnerability extends beyond simple privilege escalation to potentially compromise entire systems where Nessus agents are deployed. Organizations running Nessus in agent mode on critical systems face significant risk, as local attackers can exploit this flaw to gain unauthorized access to sensitive data, system resources, and potentially establish persistent access. The vulnerability affects not just individual systems but entire network infrastructures where Nessus agents are used for security scanning and monitoring purposes. In enterprise environments, this could lead to data breaches, system compromise, and unauthorized access to critical infrastructure. The impact is particularly severe in environments where Nessus agents run with elevated privileges or where multiple users have access to the same systems. This vulnerability essentially undermines the security posture of organizations relying on Nessus for vulnerability assessment, as it creates an opportunity for attackers to bypass the very security tools designed to protect against threats. The vulnerability's impact is amplified by the widespread use of Nessus across enterprise environments, making it a prime target for exploitation by both malicious actors and advanced persistent threat groups.
Mitigation strategies for CVE-2017-7199 focus primarily on upgrading to Nessus version 6.10.4 or later, which contains the necessary patches to address the insecure permission issues. Organizations should immediately implement this upgrade across all systems running affected Nessus versions in agent mode. Additional mitigations include implementing strict access controls on systems running Nessus agents, ensuring that only authorized personnel have local access to these systems, and monitoring for unauthorized file system modifications. Security teams should also conduct thorough audits of Nessus agent configurations to identify any systems still running vulnerable versions. The implementation of proper file system monitoring and alerting mechanisms can help detect potential exploitation attempts. From a defensive standpoint, organizations should consider implementing network segmentation to limit the potential impact of privilege escalation attacks. This vulnerability highlights the importance of maintaining current security software versions and following patch management best practices. Organizations should also consider implementing additional security controls such as mandatory access controls, file integrity monitoring, and regular security assessments to detect and prevent similar vulnerabilities in other software components. The remediation process should include comprehensive testing to ensure that the patch does not introduce compatibility issues with existing Nessus configurations or scanning operations.