CVE-2017-16873 in vagrant-vmware-fusion
Summary
by MITRE
It is possible to exploit an unsanitized PATH in the suid binary that ships with vagrant-vmware-fusion 4.0.25 through 5.0.4 in order to escalate to root privileges.
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Analysis
by VulDB Data Team • 01/18/2020
The vulnerability identified as CVE-2017-16873 represents a critical privilege escalation flaw within the vagrant-vmware-fusion virtualization plugin ecosystem. This issue affects versions 4.0.25 through 5.0.4 of the vagrant-vmware-fusion provider, which is commonly used by developers and system administrators to create and manage virtual machine environments. The vulnerability stems from improper handling of the PATH environment variable within a setuid binary, creating a dangerous condition that allows unprivileged users to gain root privileges through carefully crafted exploitation techniques. This flaw directly violates fundamental security principles by enabling arbitrary code execution with elevated privileges, potentially compromising entire systems.
The technical implementation of this vulnerability occurs within the setuid binary that is part of the vagrant-vmware-fusion plugin. When users execute vagrant commands that require elevated privileges, the system invokes a setuid binary that fails to properly sanitize the PATH environment variable before executing system commands. This unsanitized PATH variable allows attackers to manipulate the execution flow by pre-pending malicious directories to the PATH, causing the system to execute attacker-controlled binaries instead of legitimate system utilities. The vulnerability aligns with CWE-78, which describes improper neutralization of special elements used in OS commands, and CWE-250, which addresses execution with unnecessary privileges. The flaw exists because the setuid binary does not properly validate or restrict the PATH environment variable, creating an environment where attacker-controlled executables can be invoked with root privileges.
The operational impact of CVE-2017-16873 is severe and far-reaching, particularly in development environments where vagrant-vmware-fusion is commonly deployed. An attacker with access to a low-privileged user account can exploit this vulnerability to gain root access on the system, potentially leading to complete system compromise. This privilege escalation capability enables attackers to modify system files, install persistent backdoors, exfiltrate sensitive data, and establish footholds for further lateral movement within network environments. The vulnerability is particularly dangerous in enterprise settings where developers and administrators frequently use vagrant for development and testing purposes, as it can be exploited through legitimate user activities. The attack vector is relatively straightforward, requiring only that an attacker manipulate the PATH environment variable to redirect execution to malicious binaries, making this a highly exploitable flaw that aligns with ATT&CK technique T1068, which covers exploit for privilege escalation.
Mitigation strategies for CVE-2017-16873 must address both immediate remediation and long-term security posture improvements. The most effective immediate solution is to upgrade to vagrant-vmware-fusion versions that have patched this vulnerability, specifically versions beyond 5.0.4. Organizations should also implement proper PATH sanitization practices within their setuid binaries, ensuring that environment variables are properly validated and restricted to prevent manipulation. System administrators should conduct comprehensive security audits to identify all instances of setuid binaries that may exhibit similar vulnerabilities, implementing principle of least privilege where possible. Additionally, monitoring and logging should be enhanced to detect suspicious PATH manipulations or unauthorized privilege escalation attempts. The vulnerability demonstrates the critical importance of proper environment variable handling in privileged contexts and serves as a reminder that even seemingly benign security flaws can provide attackers with complete system compromise. Organizations should also consider implementing additional security controls such as mandatory access controls, capability-based security models, and regular security assessments to prevent similar vulnerabilities from being introduced in future software deployments.