CVE-2017-6718 in IOS XR
Summary
by MITRE
A vulnerability in the CLI of Cisco IOS XR Software could allow an authenticated, local attacker to elevate privileges to the root level. More Information: CSCvb99384. Known Affected Releases: 6.2.1.BASE. Known Fixed Releases: 6.2.11.3i.ROUT 6.2.1.29i.ROUT 6.2.1.26i.ROUT.
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Analysis
by VulDB Data Team • 12/29/2020
The vulnerability identified as CVE-2017-6718 represents a critical privilege escalation flaw within Cisco IOS XR Software's command line interface implementation. This security weakness affects the authentication and authorization mechanisms that govern local system access, creating a pathway for authenticated attackers to gain elevated privileges that should otherwise be restricted. The vulnerability specifically targets the CLI component of the operating system, which serves as the primary interface for system administration and configuration tasks. Attackers exploiting this flaw can leverage their existing local authentication credentials to escalate their privileges to the root level, effectively granting them complete control over the affected device. The impact is particularly severe because it undermines the fundamental security model of the system, where local access should be carefully controlled and limited to appropriate administrative functions.
The technical nature of this vulnerability stems from improper privilege validation within the CLI subsystem of Cisco IOS XR Software. When an authenticated user executes specific commands through the command line interface, the system fails to properly verify whether the user has sufficient authorization levels to perform certain administrative operations. This flaw allows malicious users to bypass normal access controls and escalate their privileges without requiring additional authentication factors or elevated permissions. The vulnerability is particularly concerning because it exists at the core operational layer of the system, making it difficult to detect and remediate without comprehensive system analysis. The affected versions demonstrate that this was not a transient issue but rather a persistent flaw that required specific software updates to address the underlying authorization mechanism failures.
The operational impact of CVE-2017-6718 extends far beyond simple privilege escalation, as it fundamentally compromises the security posture of network devices running affected IOS XR software versions. Once an attacker achieves root-level access, they can manipulate system configurations, install malicious software, modify network routing tables, and potentially use the compromised device as a pivot point for attacking other systems within the network infrastructure. This vulnerability directly violates the principle of least privilege and can enable attackers to maintain persistent access to critical network components. The security implications are particularly severe in enterprise environments where IOS XR devices often serve as core routers and switches, making them prime targets for attackers seeking to disrupt network operations or gain unauthorized access to sensitive data. The vulnerability's presence in the CLI interface also means that traditional network monitoring tools may not immediately detect the privilege escalation activity, as it occurs within legitimate administrative channels.
Mitigation strategies for this vulnerability require immediate deployment of the patched software versions provided by Cisco, specifically versions 6.2.11.3i.ROUT, 6.2.1.29i.ROUT, and 6.2.1.26i.ROUT. Organizations should prioritize patching all affected devices within their network infrastructure to prevent exploitation attempts. Additionally, network administrators should implement comprehensive monitoring of CLI access patterns and privilege escalation activities, as the vulnerability may be used to establish persistent backdoors. The implementation of multi-factor authentication for administrative access, along with regular security audits of system configurations, can help detect and prevent exploitation attempts. This vulnerability aligns with CWE-284, which addresses improper access control in software systems, and represents a classic example of how insufficient privilege validation can create severe security implications. Organizations should also consider implementing network segmentation and access control policies that limit local administrative access to only essential personnel, reducing the attack surface for such privilege escalation vulnerabilities. The ATT&CK framework categorizes this vulnerability under privilege escalation techniques, specifically targeting the use of system vulnerabilities to gain elevated access rights.