CVE-2017-9495 in MX011ANM
Summary
by MITRE
The Comcast firmware on Motorola MX011ANM (firmware version MX011AN_2.9p6s1_PROD_sey) devices allows physically proximate attackers to read arbitrary files by pressing "EXIT, Down, Down, 2" on an RF4CE remote to reach the diagnostic display, and then launching a Remote Web Inspector script.
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Analysis
by VulDB Data Team • 11/02/2019
The vulnerability described in CVE-2017-9495 represents a critical security flaw in the Comcast firmware running on Motorola MX011ANM set-top boxes. This issue stems from inadequate input validation and insufficient access controls within the device's diagnostic interface, which can be accessed through a specific sequence of remote control button presses. The vulnerability affects firmware version MX011AN_2.9p6s1_PROD_sey and demonstrates how physical proximity requirements can be bypassed through well-crafted user interaction sequences that expose sensitive system functionality.
The technical exploitation mechanism involves a precise sequence of button presses on an RF4CE remote control that navigates the device to a diagnostic display interface. This interface, which should be restricted to authorized maintenance personnel, can be accessed by any physically proximate attacker who knows the specific sequence of "EXIT, Down, Down, 2" to reach the hidden diagnostic menu. Once accessed, attackers can launch a Remote Web Inspector script that allows arbitrary file reading capabilities, effectively bypassing the device's normal security boundaries. This represents a classic case of insufficient authentication and authorization controls, where the diagnostic interface lacks proper access restrictions despite providing access to sensitive system information.
The operational impact of this vulnerability is significant as it enables attackers to extract sensitive data from the set-top box, potentially including configuration files, user credentials, network information, and other proprietary data stored on the device. The attack requires only physical proximity to the device and knowledge of the specific button sequence, making it particularly dangerous in environments where unauthorized individuals might gain access to the device. The ability to read arbitrary files creates opportunities for attackers to gather intelligence about the device's configuration, network topology, and potentially extract information that could be used for further attacks against the broader network infrastructure. This vulnerability directly maps to CWE-284, which addresses inadequate access control mechanisms, and aligns with ATT&CK technique T1059.007 for command and script interpreter usage.
Mitigation strategies for this vulnerability should focus on implementing proper access controls and authentication mechanisms for diagnostic interfaces. Device manufacturers should ensure that diagnostic menus require proper authentication credentials before granting access, and should implement time-based access restrictions or require physical security tokens for access. Network segmentation and monitoring of unusual file access patterns can help detect exploitation attempts. Additionally, regular firmware updates and security patches should be deployed to address such vulnerabilities. The solution should also include disabling or restricting access to unnecessary diagnostic interfaces when they are not actively required for maintenance operations, as recommended by security frameworks such as NIST SP 800-53. Organizations should also implement proper network monitoring to detect and alert on suspicious file access patterns that may indicate exploitation attempts.