CVE-2018-0182 in IOS XE
Summary
by MITRE
Multiple vulnerabilities in the CLI parser of Cisco IOS XE Software could allow an authenticated, local attacker to inject arbitrary commands into the CLI of the affected software, which could allow the attacker to gain access to the underlying Linux shell of an affected device and execute commands with root privileges on the device. The vulnerabilities exist because the affected software does not sufficiently sanitize command arguments before passing commands to the Linux shell for execution. An attacker could exploit these vulnerabilities by submitting a malicious CLI command to the affected software. A successful exploit could allow the attacker to break from the CLI of the affected software, which could allow the attacker to gain access to the underlying Linux shell on an affected device and execute arbitrary commands with root privileges on the device. Cisco Bug IDs: CSCuz03145, CSCuz56419, CSCva31971, CSCvb09542.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 01/17/2020
The vulnerability identified as CVE-2018-0182 represents a critical command injection flaw within the Command Line Interface parser of Cisco IOS XE Software, demonstrating a fundamental failure in input validation and sanitization. This vulnerability affects multiple Cisco devices running IOS XE software and stems from insufficient sanitization of command arguments before they are passed to the underlying Linux shell for execution. The flaw exists in the way the software processes user input through the CLI interface, creating a pathway for malicious command injection that bypasses normal security controls. The vulnerability is particularly concerning because it requires only local authentication to exploit, meaning an attacker with legitimate access to the device's CLI can leverage this weakness to escalate privileges and gain root access to the underlying operating system. This represents a classic case of insufficient input validation that directly enables privilege escalation through command injection, aligning with CWE-77 and CWE-89 categories that address command injection vulnerabilities.
The operational impact of CVE-2018-0182 extends far beyond simple privilege escalation, as successful exploitation provides attackers with complete control over affected devices through root-level access to the underlying Linux shell. Attackers can execute arbitrary commands with the highest possible privileges, potentially leading to data exfiltration, system compromise, network reconnaissance, and lateral movement within the affected network. The vulnerability affects Cisco devices including but not limited to Cisco Catalyst 9000 series switches, Cisco ISR 4000 series routers, and other network equipment running IOS XE software versions that contain the vulnerable CLI parser implementation. The exploitation process involves crafting malicious CLI commands that bypass normal input validation, allowing the attacker to break out of the restricted CLI environment and gain access to the underlying Linux shell where full system control is possible. This vulnerability creates a persistent backdoor for attackers who can maintain access even after initial compromise, as the root-level access enables them to modify system files, install malware, or establish covert communication channels.
Security practitioners must understand that this vulnerability directly maps to several ATT&CK techniques including T1059 Command and Scripting Interpreter and T1068 Exploitation for Privilege Escalation, which describes how attackers can leverage software vulnerabilities to execute commands with elevated privileges. The vulnerability also aligns with ATT&CK's T1078 Valid Accounts and T1059.007 Unix Shell which demonstrates how authenticated access combined with command injection can enable attackers to establish persistent access through shell execution. Organizations should implement comprehensive monitoring for unusual CLI activity, particularly commands that might indicate privilege escalation attempts or shell command execution. The vulnerability's exploitation requires minimal skill and can be automated, making it attractive to both malicious actors and security researchers. Network segmentation and least privilege principles become critical in mitigating the impact of such vulnerabilities, as attackers who gain access to one device can potentially use it as a pivot point to compromise other systems. Cisco has released multiple bug IDs including CSCuz03145, CSCuz56419, CSCva31971, and CSCvb09542 to track different aspects of this vulnerability across various affected software versions and device types.
Mitigation strategies for CVE-2018-0182 primarily focus on immediate software updates and patches provided by Cisco, as the vulnerability requires a software fix to address the underlying CLI parser sanitization issues. Organizations should prioritize patching all affected devices, particularly those running vulnerable IOS XE software versions, and verify that the patches have been successfully applied. Network administrators should implement strict access controls and monitoring for CLI usage, particularly monitoring for commands that might indicate exploitation attempts such as shell command execution or unusual privilege escalation patterns. The vulnerability's nature suggests that organizations should also consider implementing network access controls to limit local access to network devices, reducing the attack surface for authenticated local attackers. Regular security assessments and vulnerability scanning should be conducted to identify other potential command injection vulnerabilities in network infrastructure. Additionally, implementing robust logging and monitoring of CLI sessions can help detect exploitation attempts, while regular security training for network administrators can reduce the risk of social engineering attacks that might lead to authenticated access. The vulnerability's classification as a local privilege escalation issue also emphasizes the importance of maintaining secure administrative practices and regularly reviewing access controls to prevent unauthorized local access to network devices.