CVE-2019-12671 in IOS XE
Summary
by MITRE
A vulnerability in the CLI of Cisco IOS XE Software could allow an authenticated, local attacker to gain shell access on an affected device and execute commands on the underlying operating system (OS). The vulnerability is due to insufficient enforcement of the consent token in authorizing shell access. An attacker could exploit this vulnerability by authenticating to the CLI and requesting shell access on an affected device. A successful exploit could allow the attacker to gain shell access on the affected device and execute commands on the underlying OS.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 12/28/2023
This vulnerability resides in the command line interface of Cisco IOS XE software, representing a critical authorization flaw that enables local attackers to escalate privileges and execute arbitrary commands on the underlying operating system. The issue stems from inadequate validation of consent tokens during the shell access authorization process, creating a pathway for authenticated users to bypass normal security controls. The vulnerability specifically affects devices running Cisco IOS XE Software where the CLI component fails to properly enforce token-based authorization mechanisms that should prevent unauthorized shell access.
The technical implementation of this flaw involves the CLI subsystem's failure to adequately validate consent tokens when users attempt to escalate privileges to shell access level. When an authenticated user requests shell access through the CLI, the system should verify proper authorization tokens before granting elevated privileges. However, the insufficient enforcement allows attackers to proceed with shell access requests without proper validation, effectively bypassing the intended security boundaries between standard user access and privileged shell execution. This represents a clear violation of the principle of least privilege and proper access control enforcement.
Operationally, this vulnerability presents a severe risk to network infrastructure security as it allows an attacker who has already established authentication credentials to escalate their privileges without additional authorization checks. The impact extends beyond simple command execution to full system compromise, enabling attackers to manipulate network configurations, access sensitive data, install malicious software, or establish persistent access points within the network. The local nature of the attack means that any user with valid CLI credentials can potentially exploit this vulnerability, making it particularly dangerous in environments where multiple users have administrative access or where credentials may be compromised through social engineering or other means.
From a cybersecurity framework perspective, this vulnerability aligns with CWE-284 (Improper Access Control) and represents a failure in the authorization mechanism that should prevent privilege escalation. The ATT&CK framework categorizes this as a privilege escalation technique where an attacker leverages a weakness in the system's access control to gain elevated privileges. Organizations should implement immediate mitigations including applying the relevant Cisco security patches, reviewing and tightening CLI access controls, implementing strict monitoring of shell access requests, and conducting comprehensive access reviews to ensure that only authorized personnel have the necessary privileges to request shell access. Additionally, network segmentation and monitoring solutions should be deployed to detect and alert on suspicious shell access patterns that may indicate exploitation attempts.