CVE-2017-9496 in MX011ANM
Summary
by MITRE
The Comcast firmware on Motorola MX011ANM (firmware version MX011AN_2.9p6s1_PROD_sey) devices allows physically proximate attackers to access an SNMP server by connecting a cable to the Ethernet port, and then establishing communication with the device's link-local IPv6 address.
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Analysis
by VulDB Data Team • 11/02/2019
The vulnerability described in CVE-2017-9496 represents a critical security flaw in Comcast's firmware implementation for Motorola MX011ANM gateway devices. This issue stems from inadequate network security configuration that exposes sensitive management services to unauthorized physical access. The vulnerability specifically affects firmware version MX011AN_2.9p6s1_PROD_sey and demonstrates how poorly configured network services can create significant attack vectors for physically proximate adversaries. The flaw allows attackers to gain access to the Simple Network Management Protocol (SNMP) server without requiring any authentication credentials, making it particularly dangerous as it bypasses traditional authentication mechanisms entirely.
The technical implementation of this vulnerability occurs through a combination of weak network configuration and insufficient access controls. When an attacker physically connects to the device via Ethernet cable, they can establish communication with the device's link-local IPv6 address, which serves as the primary entry point for accessing the exposed SNMP service. This approach leverages the fact that the device's SNMP server is configured to listen on all available network interfaces without proper authentication or access restriction mechanisms. The link-local IPv6 address provides a direct communication channel that does not require complex network traversal or sophisticated attack techniques, making the exploit straightforward for adversaries with physical access to the device. This configuration violates fundamental security principles regarding service exposure and access control enforcement.
The operational impact of this vulnerability extends beyond simple unauthorized access to encompass potential network compromise and data exposure. An attacker with physical proximity can access sensitive network management information, potentially gaining insights into network topology, device configurations, and management credentials. The SNMP protocol typically provides extensive access to network device management functions, including configuration data, performance metrics, and operational parameters that could be exploited for further attacks. This vulnerability creates a pathway for attackers to escalate privileges and potentially gain control over the entire network infrastructure managed by the affected device, particularly when combined with other network reconnaissance activities. The low barrier to entry for exploitation means that even non-technical adversaries can potentially exploit this vulnerability effectively.
Mitigation strategies for CVE-2017-9496 should focus on restricting access to the SNMP service and implementing proper network segmentation controls. The primary recommendation involves configuring the device to disable or restrict SNMP access to only trusted management networks, ensuring that the service is not exposed through physical network interfaces. Network administrators should implement proper access control lists and firewall rules that prevent unauthorized access to the SNMP port from untrusted network segments. Additionally, the device firmware should be updated to a version that properly configures the SNMP service with appropriate authentication mechanisms and access restrictions. This vulnerability aligns with CWE-284, which addresses inadequate access control, and represents a clear violation of the principle of least privilege in network security. Organizations should also consider implementing network monitoring solutions that can detect unauthorized SNMP access attempts and alert security personnel to potential exploitation activities. The ATT&CK framework categorizes this vulnerability under network service scanning and unauthorized access techniques, emphasizing the importance of physical security controls in preventing such attacks.