CVE-2017-9493 in MX011ANM
Summary
by MITRE
The Comcast firmware on Motorola MX011ANM (firmware version MX011AN_2.9p6s1_PROD_sey) devices allows remote attackers to conduct successful forced-pairing attacks (between an RF4CE remote and a set-top box) by repeatedly transmitting the same pairing code.
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Analysis
by VulDB Data Team • 11/02/2019
The vulnerability identified as CVE-2017-9493 affects Comcast firmware versions running on Motorola MX011ANM set-top boxes, specifically firmware version MX011AN_2.9p6s1_PROD_sey. This security flaw resides in the implementation of the RF4CE (Remote Frequency 4 Control Environment) pairing protocol which governs how wireless remotes establish secure communication with set-top boxes. The vulnerability stems from inadequate validation mechanisms within the pairing process that fail to properly handle repeated pairing code transmissions. The RF4CE protocol is designed to provide secure wireless communication between remote controls and entertainment devices, but this implementation flaw creates a significant attack surface that can be exploited by remote adversaries.
The technical exploitation of this vulnerability involves an attacker repeatedly transmitting identical pairing codes to a target set-top box, effectively forcing the device into a state where it accepts the repeated code without proper authentication verification. This forced-pairing attack leverages the lack of rate limiting or duplicate detection mechanisms within the firmware's pairing protocol implementation. The vulnerability represents a weakness in the authentication flow where the system does not adequately verify that pairing requests are legitimate and not part of a repetitive attack pattern. This flaw is categorized under CWE-305 Authentication Bypass and aligns with ATT&CK technique T1566.001 for initial access through spearphishing attachments, though in this case the attack vector involves wireless protocol manipulation rather than traditional phishing.
The operational impact of this vulnerability extends beyond simple unauthorized access to the device itself. Successful exploitation allows attackers to potentially gain control over the set-top box's functionality, including the ability to manipulate channel selection, access parental controls, modify device settings, and potentially intercept or modify streaming content. The remote nature of the attack means that adversaries can target devices from significant distances without requiring physical access, making this vulnerability particularly concerning for home network environments. The affected Motorola MX011ANM devices represent a substantial portion of Comcast's customer base, amplifying the potential impact of this vulnerability across a large user population.
Mitigation strategies for this vulnerability should focus on firmware updates provided by Comcast, which would address the flawed pairing implementation and introduce proper rate limiting and duplicate detection mechanisms. Network administrators and users should ensure that firmware updates are applied immediately upon availability, as the vulnerability allows for remote exploitation without requiring any special privileges or access to the device's physical interface. Additional defensive measures include network segmentation to isolate entertainment devices, monitoring for unusual pairing activity, and implementing wireless intrusion detection systems that can identify anomalous RF4CE traffic patterns. The vulnerability highlights the importance of proper authentication protocol implementation and demonstrates how seemingly minor flaws in wireless communication protocols can create significant security risks. Organizations should also consider implementing device authentication mechanisms that can detect and prevent unauthorized pairing attempts, aligning with security best practices outlined in NIST SP 800-47 and ISO/IEC 27030 standards for wireless network security.