CVE-2019-1682 in Application Policy Infrastructure Controller
Summary
by MITRE
A vulnerability in the FUSE filesystem functionality for Cisco Application Policy Infrastructure Controller (APIC) software could allow an authenticated, local attacker to escalate privileges to root on an affected device. The vulnerability is due to insufficient input validation for certain command strings issued on the CLI of the affected device. An attacker with write permissions for files within a readable folder on the device could alter certain definitions in the affected file. A successful exploit could allow an attacker to cause the underlying FUSE driver to execute said crafted commands, elevating the attacker's privileges to root on an affected device.
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Analysis
by VulDB Data Team • 09/12/2023
The vulnerability identified as CVE-2019-1682 resides within the FUSE filesystem functionality of Cisco Application Policy Infrastructure Controller (APIC) software, representing a critical privilege escalation flaw that fundamentally undermines system security. This vulnerability specifically targets the command-line interface of the APIC device, where insufficient input validation creates a dangerous attack surface for authenticated local adversaries. The flaw manifests when the system processes command strings through the FUSE driver mechanism, which executes commands without adequate sanitization or verification of user input. The vulnerability is particularly concerning because it requires only local authentication and write permissions within a readable directory, making it accessible to attackers who have already gained some level of system access. The exploitation process leverages the FUSE driver's trust in command execution, allowing crafted inputs to be interpreted and executed with elevated privileges.
The technical exploitation of CVE-2019-1682 follows a well-defined attack pattern that aligns with common privilege escalation methodologies and maps directly to CWE-78, which describes improper neutralization of special elements used in OS commands. Attackers can manipulate specific files within the system where they possess write permissions, particularly targeting configuration or definition files that are subsequently processed by the FUSE driver. When these modified files are accessed or processed, the FUSE subsystem executes the malicious command strings contained within them, effectively bypassing normal access controls and privilege boundaries. The underlying mechanism relies on the FUSE driver's design to interpret and execute commands directly from file content, creating a direct path from file manipulation to root privilege execution. This vulnerability demonstrates a classic case of command injection within a filesystem context where the FUSE subsystem acts as an intermediary between file content and system execution.
The operational impact of CVE-2019-1682 extends beyond simple privilege escalation, as it provides attackers with complete control over the affected Cisco APIC device, which serves as a critical infrastructure component in network policy management. The compromised device could then be used to monitor network traffic, modify access policies, disable security controls, or serve as a pivot point for further attacks within the network infrastructure. This vulnerability particularly affects organizations that rely heavily on Cisco APIC for application policy management, as the compromise of such a device can lead to widespread network security degradation. The attack vector is relatively straightforward for skilled adversaries who can gain local access through legitimate means, making the vulnerability particularly dangerous in environments where local access controls are not strictly enforced. The impact is amplified by the fact that APIC devices often maintain sensitive network policy information and control critical network functions, making them attractive targets for attackers seeking persistent access to enterprise networks.
Mitigation strategies for CVE-2019-1682 must address both the immediate vulnerability and broader security posture of affected systems. Cisco has released patches and software updates specifically addressing this vulnerability, which should be deployed immediately across all affected APIC installations. Organizations should implement strict file access controls and monitoring of directories where FUSE operations occur, ensuring that only authorized users can modify critical system files. The principle of least privilege should be enforced rigorously, limiting write permissions to only those users and processes that absolutely require them. Network segmentation and monitoring solutions should be employed to detect unusual command execution patterns or unauthorized file modifications that could indicate exploitation attempts. Additionally, regular security assessments should be conducted to identify and remediate similar input validation flaws in other system components, as this vulnerability type represents a common class of security weaknesses. The remediation process should also include comprehensive testing to ensure that the applied patches do not disrupt legitimate network operations while effectively closing the privilege escalation pathway. Security teams should consider implementing behavioral monitoring and anomaly detection systems specifically designed to identify suspicious FUSE driver activity or command execution patterns that could indicate exploitation attempts.