CVE-2019-20546 in Samsung
Summary
by MITRE
An issue was discovered on Samsung mobile devices with N(7.x), O(8.x), and P(9.0) (Broadcom Wi-Fi chipsets) software. A denial-of-service attack can leverage a shared interface between Broadcom Bluetooth and Broadcom Wi-Fi. The Samsung ID is SVE-2019-15350 (November 2019).
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Analysis
by VulDB Data Team • 10/04/2020
This vulnerability affects Samsung mobile devices running Android versions 7.x, 8.x, and 9.0 that utilize Broadcom Wi-Fi chipsets. The issue stems from a shared interface architecture between the Broadcom Bluetooth and Broadcom Wi-Fi components within the device's wireless communication stack. The fundamental flaw occurs when the Bluetooth and Wi-Fi subsystems share common hardware resources or software interfaces without proper isolation mechanisms, creating a potential attack vector that can be exploited by malicious actors to disrupt normal device operations.
The technical implementation of this vulnerability involves the exploitation of resource contention and interface sharing between the two wireless subsystems. When a malicious entity crafts specific Bluetooth packets or triggers particular Wi-Fi operations, the shared interface can become overwhelmed or corrupted, leading to system instability. This shared resource model creates a scenario where a denial-of-service condition can be triggered simply by manipulating one wireless subsystem to affect the other. The vulnerability represents a classic case of insufficient hardware abstraction and software isolation between critical system components, allowing cross-contamination of resources that should remain logically separated.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise the overall reliability and security posture of affected Samsung devices. Users may experience unexpected device reboots, complete wireless communication failure, or the inability to establish secure connections to networks. In a broader security context, this vulnerability could serve as a stepping stone for more sophisticated attacks, as the device's wireless capabilities become unreliable and potentially exploitable. The shared interface nature means that attackers could potentially use this weakness to create persistent service disruptions or to mask other malicious activities by overwhelming the device's wireless stack.
From a cybersecurity perspective, this vulnerability aligns with CWE-362, which addresses concurrent execution using shared resource access, and represents a significant concern for mobile device security. The ATT&CK framework would categorize this under T1499.002, which involves network denial of service attacks. Mitigation strategies should focus on implementing proper isolation between wireless subsystems through firmware updates, ensuring that Bluetooth and Wi-Fi components maintain separate resource allocation, and applying patches that address the shared interface implementation. Samsung's response included firmware updates that modified the interface sharing mechanisms to prevent cross-contamination between the two wireless subsystems, effectively addressing the root cause of the vulnerability.
The broader implications of this vulnerability highlight the challenges inherent in mobile device security architecture, particularly when multiple wireless technologies must coexist within a single hardware platform. This case demonstrates how seemingly minor architectural decisions regarding shared resources can create significant security risks that affect millions of devices. The vulnerability also underscores the importance of proper security testing during the development lifecycle, particularly for integrated wireless subsystems where interface sharing is common but not adequately protected against malicious exploitation. Organizations should prioritize regular security assessments of wireless interfaces and maintain robust patch management processes to address similar architectural weaknesses that may exist in other device components or third-party integrations.