CVE-2017-12229 in IOS XE
Summary
by MITRE
A vulnerability in the REST API of the web-based user interface (web UI) of Cisco IOS XE 3.1 through 16.5 could allow an unauthenticated, remote attacker to bypass authentication to the REST API of the web UI of the affected software. The vulnerability is due to insufficient input validation for the REST API of the affected software. An attacker could exploit this vulnerability by sending a malicious API request to an affected device. A successful exploit could allow the attacker to bypass authentication and gain access to the web UI of the affected software. This vulnerability affects Cisco devices that are running a vulnerable release of Cisco IOS XE Software, if the HTTP Server feature is enabled for the device. The newly redesigned, web-based administration UI was introduced in the Denali 16.2 Release of Cisco IOS XE Software. This vulnerability does not affect the web-based administration UI in earlier releases of Cisco IOS XE Software. Cisco Bug IDs: CSCuz46036.
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Analysis
by VulDB Data Team • 01/14/2021
The vulnerability identified as CVE-2017-12229 represents a critical authentication bypass flaw within the REST API of Cisco IOS XE Software's web-based user interface. This issue affects versions 3.1 through 16.5 and specifically targets devices where the HTTP Server feature is enabled, creating a significant security risk for organizations relying on Cisco networking equipment. The vulnerability stems from inadequate input validation mechanisms within the REST API implementation, which fails to properly sanitize or verify incoming requests before processing them. This weakness allows an unauthenticated remote attacker to craft malicious API requests that can circumvent the normal authentication procedures required to access the web UI. The flaw is particularly concerning because it operates entirely outside the normal security boundaries of the device, enabling attackers to gain unauthorized access to administrative functions without requiring valid credentials or prior access to the network.
The technical exploitation of this vulnerability occurs through carefully crafted API requests that exploit the insufficient input validation controls. When the REST API processes these malformed requests, the system fails to properly validate the input parameters, allowing malicious payloads to be interpreted as legitimate authentication requests. This type of vulnerability aligns with CWE-20, which describes improper input validation, and represents a classic example of how weak validation controls can lead to authentication bypass scenarios. The attack vector is entirely remote and does not require any physical access to the device or prior network credentials, making it particularly dangerous for network administrators. The vulnerability specifically affects the newly redesigned web-based administration UI introduced in the Denali 16.2 release of Cisco IOS XE Software, meaning that organizations running earlier versions are not affected by this particular flaw, though they may face other security concerns.
The operational impact of this vulnerability extends beyond simple unauthorized access to encompass potential full administrative control over affected Cisco devices. Once an attacker successfully bypasses authentication, they can access sensitive configuration data, modify device settings, and potentially use the compromised device as a pivot point for further attacks within the network. This vulnerability directly violates the principle of least privilege and could enable attackers to establish persistent access to network infrastructure. The implications are particularly severe for enterprise networks where Cisco IOS XE devices serve as core routing and switching infrastructure, as unauthorized access to these devices can compromise entire network segments. Organizations may face regulatory compliance issues and potential data breaches if this vulnerability is exploited, especially in environments where network security is paramount. The vulnerability also affects the integrity and confidentiality of network operations, as attackers could potentially modify routing tables, disable security features, or extract sensitive network information.
Cisco has addressed this vulnerability through software updates and patches released as part of their regular security maintenance cycle, with the specific bug identified as CSCuz46036. Network administrators should prioritize applying these patches to all affected devices running vulnerable versions of Cisco IOS XE Software, particularly those with HTTP Server enabled. The mitigation strategy involves updating to the latest stable release of Cisco IOS XE Software that includes the necessary security fixes, which typically incorporate improved input validation controls and enhanced authentication mechanisms. Organizations should also implement network segmentation and monitoring to detect unusual API access patterns that might indicate exploitation attempts. Additional defensive measures include disabling HTTP Server functionality on devices where it is not required, implementing network access controls to restrict API access to trusted IP addresses, and conducting regular vulnerability assessments to identify similar issues within the network infrastructure. Security teams should monitor Cisco's security advisories and maintain updated threat intelligence to stay informed about similar vulnerabilities that may affect their Cisco IOS XE deployments. The remediation process should also include comprehensive testing of patches in non-production environments to ensure compatibility and prevent service disruptions while maintaining network security posture.