CVE-2018-0481 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.
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Analysis
by VulDB Data Team • 05/22/2023
The vulnerability identified as CVE-2018-0481 represents a critical command injection flaw within the Command Line Interface parser of Cisco IOS XE Software, specifically affecting devices running this operating system. This issue arises from insufficient input validation mechanisms that fail to properly sanitize command arguments passed to the underlying Linux shell. The flaw exists at the intersection of privilege escalation and command execution, creating a pathway for authenticated local attackers to gain unauthorized root-level access to affected network devices. The vulnerability is particularly concerning because it leverages existing privileged access within the system to bypass normal security controls and execute arbitrary code with the highest possible privileges.
The technical implementation of this vulnerability stems from improper argument sanitization within the CLI processing layer of IOS XE software. When legitimate administrative users execute CLI commands with specific argument patterns, the system fails to adequately filter or escape special characters that could be interpreted by the underlying Linux shell. This parsing deficiency allows attackers with privilege level 15 access to craft malicious command sequences that inadvertently invoke shell execution contexts. The vulnerability is categorized under CWE-78 as a "Improper Neutralization of Special Elements used in a Command" which directly relates to the failure to properly sanitize input before shell command execution. This type of flaw enables attackers to manipulate the command parsing mechanism to achieve unintended behavior.
From an operational impact perspective, this vulnerability presents a severe threat to network infrastructure security as it requires only authenticated access at the highest privilege level to exploit. Network administrators who maintain legitimate access to devices through privileged EXEC mode can leverage this weakness to execute arbitrary commands with root privileges, effectively compromising the entire device. The attack surface includes all Cisco devices running affected versions of IOS XE software, particularly those with CLI interfaces that process user input. Successful exploitation could lead to complete device compromise, data exfiltration, network disruption, and potential lateral movement within the network infrastructure. The vulnerability essentially transforms a legitimate administrative interface into a backdoor for privilege escalation attacks.
Mitigation strategies for CVE-2018-0481 should prioritize immediate patching of affected devices through official Cisco software updates and security advisories. Organizations must ensure all IOS XE devices are updated to versions that address the command argument sanitization issues. Network segmentation and access control measures should be implemented to limit the potential impact of compromised devices, including restricting physical and logical access to privileged accounts. Monitoring systems should be configured to detect unusual CLI command patterns that might indicate exploitation attempts, particularly focusing on command sequences that could trigger shell execution. The ATT&CK framework categorizes this vulnerability under T1059.004 for "Command and Scripting Interpreter: PowerShell" and T1068 for "Exploitation for Privilege Escalation" as the attack patterns align with these techniques for executing commands and escalating privileges within compromised systems. Regular security assessments and input validation reviews should be conducted to prevent similar vulnerabilities from emerging in other components of the network infrastructure.