CVE-2016-1366 in IOS XR
Summary
by MITRE
The SCP and SFTP modules in Cisco IOS XR 5.0.0 through 5.2.5 on Network Convergence System 6000 devices use weak permissions for system files, which allows remote authenticated users to cause a denial of service (overwrite) via unspecified vectors, aka Bug ID CSCuw75848.
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Analysis
by VulDB Data Team • 07/11/2022
The vulnerability identified as CVE-2016-1366 affects Cisco IOS XR software versions 5.0.0 through 5.2.5 running on Network Convergence System 6000 devices. This issue specifically targets the Secure Copy Protocol and Secure File Transfer Protocol modules, which are critical components for secure file operations within network infrastructure. The vulnerability stems from improper file permission settings that create exploitable conditions for authenticated remote attackers. According to the bug ID CSCuw75848, the weakness manifests in how system files are configured with insufficient access controls, allowing malicious actors with valid credentials to manipulate critical system resources.
The technical flaw involves the SCP and SFTP modules failing to implement proper file permission controls for system files, creating a path for unauthorized file modifications. This weakness enables authenticated attackers to potentially overwrite critical system files, leading to service disruption and system instability. The unspecified vectors suggest that the attack surface encompasses multiple potential entry points within the file transfer mechanisms, making the vulnerability particularly concerning for network administrators. The weak permissions essentially create a backdoor for file manipulation that bypasses normal security controls, allowing attackers to compromise the integrity of system files without requiring elevated privileges beyond standard authentication.
Operationally, this vulnerability poses a significant risk to network infrastructure stability and security posture. Remote authenticated attackers can leverage the weak file permissions to perform denial of service attacks by overwriting critical system files, potentially causing device crashes, service interruptions, or complete system failure. The impact extends beyond simple service disruption as corrupted system files could lead to extended downtime, requiring manual intervention for system recovery and potentially necessitating complete device reinstallation. Network convergence system 6000 devices that rely on these protocols for configuration management, software updates, and operational file transfers become particularly vulnerable, as attackers could compromise the entire network infrastructure through targeted file overwrites.
Organizations should implement immediate mitigations including applying the latest Cisco security patches and updates to address the weak file permission settings in the affected IOS XR versions. Network administrators must also consider implementing additional access controls and monitoring for unusual file modification activities within the SCP and SFTP modules. The vulnerability aligns with CWE-732, which addresses inadequate permissions for critical resources, and represents a significant concern under the ATT&CK framework's privilege escalation and defense evasion techniques. Regular security assessments should verify that file permissions have been properly configured and that no unauthorized modifications have occurred. Additionally, network segmentation and access control policies should be strengthened to limit the potential impact of such vulnerabilities, particularly in environments where multiple users have access to network device management interfaces.