CVE-2009-0637 in IOS
Summary
by MITRE
The SCP server in Cisco IOS 12.2 through 12.4, when Role-Based CLI Access is enabled, does not enforce the CLI view configuration for file transfers, which allows remote authenticated users with an attached CLI view to (1) read or (2) overwrite arbitrary files via an SCP command.
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Analysis
by VulDB Data Team • 05/03/2025
The vulnerability identified as CVE-2009-0637 represents a critical authorization bypass flaw in Cisco IOS software versions 12.2 through 12.4. This issue specifically affects devices configured with Role-Based CLI Access controls, which are designed to restrict user privileges and limit access to specific command sets within the router or switch interface. The vulnerability stems from a fundamental failure in the Secure Copy Protocol server implementation where the system does not properly validate file access permissions against the configured CLI view restrictions. When Role-Based CLI Access is enabled, users are typically confined to specific command hierarchies and view configurations that should govern their operational capabilities. However, this flaw allows authenticated users who have been assigned to a particular CLI view to circumvent these restrictions during file transfer operations.
The technical exploitation of this vulnerability occurs through the Secure Copy Protocol which is commonly used for secure file transfers between network devices and hosts. When an authenticated user with a limited CLI view attempts to perform file operations via SCP, the system fails to enforce the view-based restrictions that should normally prevent access to files outside the user's designated scope. This creates two distinct attack vectors: the ability to read arbitrary files that should be restricted to higher privilege users, and the capability to overwrite files that could potentially include system configuration files or critical operational data. The flaw essentially allows privilege escalation through file system access manipulation, bypassing the intended security boundaries established by the Role-Based CLI configuration.
The operational impact of this vulnerability extends beyond simple unauthorized file access, as it fundamentally undermines the principle of least privilege that network administrators rely upon for device security. An attacker with legitimate access to a restricted CLI view could potentially extract sensitive configuration data, system files, or operational information that should remain protected within the network infrastructure. Additionally, the ability to overwrite arbitrary files could lead to system instability, service disruption, or even complete device compromise if critical system files are modified. This vulnerability is particularly concerning in enterprise environments where multiple users with varying privilege levels access network devices through CLI interfaces, as it allows for persistent unauthorized access to critical network resources.
Organizations should implement immediate mitigations including disabling SCP functionality when Role-Based CLI Access is enabled, applying the latest Cisco IOS patches that address this specific vulnerability, and reviewing all CLI view configurations to ensure proper privilege separation. Network administrators should also consider implementing additional access controls such as SSH key-based authentication with restricted command execution, and establishing more granular file access controls outside of the CLI environment. From a compliance perspective, this vulnerability violates security standards such as those outlined in the NIST SP 800-53 controls related to access control and system configuration management. The flaw aligns with CWE-284 (Improper Access Control) and can be mapped to ATT&CK technique T1078.004 (Valid Accounts: SSH) where attackers leverage legitimate credentials to perform unauthorized operations. Organizations should also consider implementing network segmentation and monitoring solutions to detect anomalous SCP activity patterns that might indicate exploitation attempts.