CVE-2018-0477 in IOS XE
Summary
by MITRE
A vulnerability in the CLI parser of Cisco IOS XE Software could allow an authenticated, local attacker to execute commands on the underlying Linux shell of an affected device with root privileges. The vulnerability exist because the affected software improperly sanitizes command arguments, failing to prevent access to certain internal data structures on an affected device. An attacker who has privileged EXEC mode (privilege level 15) access to an affected device could exploit these vulnerabilities on the device by executing CLI commands that contain custom arguments. A successful exploit could allow the attacker to execute arbitrary commands with root privileges on the affected device.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 05/22/2023
The vulnerability identified as CVE-2018-0477 represents a critical command injection flaw within Cisco IOS XE Software that undermines the security boundaries of network infrastructure devices. This vulnerability specifically targets the Command Line Interface parser implementation, which serves as the primary administrative interface for configuring and managing Cisco network devices. The flaw manifests when the system fails to properly sanitize user-supplied arguments passed to CLI commands, creating an avenue for malicious input to bypass normal security controls and access underlying system components. The vulnerability affects multiple Cisco IOS XE Software versions and impacts a wide range of network equipment including routers and switches that utilize this operating system. The root cause of this issue stems from inadequate input validation and sanitization practices within the CLI processing pipeline, allowing attackers to manipulate command arguments in ways that were not anticipated by the software design.
The technical exploitation of this vulnerability requires an attacker to possess privileged EXEC mode access with privilege level 15, which represents the highest administrative level within Cisco IOS XE systems. This prerequisite significantly limits the attack surface but does not eliminate the severity of the flaw, as obtaining such access through legitimate means such as administrative credentials or social engineering presents a realistic threat scenario. When an authenticated attacker executes specific CLI commands containing maliciously crafted arguments, the system's insufficient sanitization allows these inputs to be interpreted by the underlying Linux shell without proper validation. This creates a direct path for arbitrary command execution with root privileges, effectively granting the attacker complete control over the device's operating system. The vulnerability is classified as a command injection flaw and aligns with CWE-77 and CWE-88 categories, which specifically address improper input handling and command execution vulnerabilities. The flaw essentially allows attackers to escalate their privileges from administrative user level to system root level, bypassing all normal security controls and access restrictions.
The operational impact of CVE-2018-0477 extends far beyond simple privilege escalation, as it provides attackers with complete system compromise capabilities that can be leveraged for network reconnaissance, lateral movement, and persistent access. Once an attacker achieves root-level access through this vulnerability, they can modify system configurations, install malicious software, steal sensitive data, or establish backdoor access points for future exploitation. The vulnerability's impact is particularly concerning because it affects the fundamental management interface of network infrastructure devices, potentially allowing attackers to disrupt network operations, redirect traffic, or create denial of service conditions. From an attacker's perspective, this vulnerability represents a gold mine for network penetration testing and advanced persistent threat campaigns, as it provides a reliable method for achieving system-level control without requiring physical access or complex exploitation techniques. The vulnerability also aligns with ATT&CK technique T1059.004, which covers command and scripting interpreter execution, and T1068, which addresses local privilege escalation, making it a valuable target for threat actors seeking to maintain persistent access within network environments.
Organizations affected by this vulnerability should implement immediate mitigations including applying the latest security patches provided by Cisco, which address the input sanitization issues in the CLI parser. Network segmentation and privilege minimization strategies should be enforced to reduce the potential impact of successful exploitation, ensuring that administrative access is limited to only necessary personnel with proper authorization. Regular monitoring of device logs for suspicious CLI activity and command execution patterns can help detect potential exploitation attempts, while implementing network access controls and secure configuration practices can further reduce the attack surface. The vulnerability highlights the critical importance of proper input validation and sanitization in system design, particularly for administrative interfaces that handle user-supplied data. Security teams should conduct thorough vulnerability assessments to identify any other similar issues in their network infrastructure and implement comprehensive monitoring solutions that can detect anomalous command execution patterns. Additionally, organizations should review their administrative access controls and ensure that privilege levels are properly managed to minimize the potential impact of such vulnerabilities, as the requirement for privilege level 15 access means that successful exploitation can occur through legitimate administrative accounts that have not been properly secured.