CVE-2013-4875 in Wireless Network Extender
Summary
by MITRE
The Uboot bootloader on the Verizon Wireless Network Extender SCS-2U01 allows physically proximate attackers to bypass the intended boot process and obtain a login prompt by connecting a crafted HDMI cable and sending a SysReq interrupt.
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Analysis
by VulDB Data Team • 08/16/2024
The vulnerability identified as CVE-2013-4875 represents a critical security flaw in the Uboot bootloader implementation of the Verizon Wireless Network Extender SCS-2U01 device. This issue stems from inadequate physical security measures within the bootloader's boot process, creating an exploitable pathway that allows attackers with physical proximity to bypass normal authentication mechanisms. The device in question serves as a critical component in wireless network infrastructure, facilitating communication between cellular networks and local networks, making its security implications particularly severe.
The technical exploitation of this vulnerability relies on the attacker's ability to physically connect a specially crafted HDMI cable to the device while simultaneously triggering a SysReq interrupt sequence. This interrupt mechanism, typically used for system debugging and emergency procedures, becomes weaponized in this context to manipulate the bootloader's execution flow. The flaw exists because the Uboot implementation does not properly validate the legitimacy of interrupt sources or verify the authenticity of the connection attempt, allowing malicious input to override the intended boot sequence. This represents a classic example of insufficient input validation and improper privilege handling, categorized under CWE-254 in the Common Weakness Enumeration framework.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it provides attackers with direct access to the device's login prompt without requiring knowledge of valid credentials or network authentication details. This physical attack vector significantly reduces the barrier to exploitation compared to network-based attacks, as it eliminates the need for remote access capabilities or complex network reconnaissance. The device's role as a network extender means that successful exploitation could potentially provide attackers with access to internal network traffic, device configuration, or even serve as a foothold for broader network infiltration activities. This aligns with ATT&CK technique T1059.001 for command and control through system shell access and T1072 for application deployment via physical access.
Mitigation strategies for this vulnerability must address both the immediate physical security concerns and the underlying bootloader implementation weaknesses. The most effective approach involves firmware updates that properly validate interrupt sources and implement proper authentication checks during the boot process. Network administrators should also implement physical security controls such as restricted access to device locations, cable management solutions, and monitoring for unauthorized physical connections. Additionally, the device should be configured to disable unnecessary physical interfaces when not actively in use, and regular security assessments should be conducted to identify similar vulnerabilities in other network infrastructure components. The vulnerability demonstrates the critical importance of secure boot implementation and highlights how physical security measures must be integrated into the overall security architecture of network devices to prevent such bypass scenarios from occurring.