CVE-2020-28656 in Polo
Summary
by MITRE • 11/16/2020
The update functionality of the Discover Media infotainment system in Volkswagen Polo 2019 vehicles allows physically proximate attackers to execute arbitrary code because some unsigned parts of a metainfo file are parsed, which can cause attacker-controlled files to be written to the infotainment system and executed as root.
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Analysis
by VulDB Data Team • 12/07/2020
The vulnerability identified as CVE-2020-28656 represents a critical security flaw within the Discover Media infotainment system of 2019 Volkswagen Polo vehicles, classified under the Common Weakness Enumeration category CWE-436. This vulnerability stems from insufficient validation of update metadata within the system's software update mechanism, creating an attack surface that allows malicious actors with physical proximity to the vehicle to gain complete system control. The flaw specifically manifests in the parsing of metainfo files during the update process, where unsigned components are processed without proper integrity verification, enabling attackers to manipulate the update procedure and execute arbitrary code with root privileges.
The technical implementation of this vulnerability exploits the trust model inherent in the infotainment system's update protocol, where the system assumes that any data received during the update process is legitimate and safe to execute. When an attacker places a maliciously crafted update file within the vehicle's update directory, the system's parser processes the unsigned metainfo components without validating their authenticity or integrity. This parsing behavior creates a path for attackers to inject executable code that will be executed with the highest privileges available within the system, effectively granting them root access to the infotainment system's core operations.
From an operational perspective, this vulnerability presents a significant risk to vehicle security and user privacy, as it allows attackers with physical access to the vehicle to gain complete control over the infotainment system and potentially extend their attack surface to other vehicle components. The attack requires only physical proximity to the vehicle, making it particularly concerning for automotive environments where unauthorized access might occur in parking lots, garages, or other public spaces. The root-level execution capability means that attackers could potentially access sensitive data, modify system configurations, or even use the infotainment system as a pivot point to target other vehicle systems that may be connected to the same network infrastructure.
The implications of this vulnerability extend beyond simple code execution, as it represents a fundamental failure in the automotive cybersecurity framework for vehicle infotainment systems. According to the ATT&CK framework for automotive systems, this vulnerability maps to techniques involving privilege escalation and persistence mechanisms, as the attacker gains root access and can establish long-term control over the vehicle's entertainment system. The vulnerability also highlights the importance of secure update mechanisms in automotive environments, where traditional software security practices must be adapted to account for the physical attack surface that vehicles present. Organizations implementing automotive cybersecurity measures should consider this vulnerability when developing their threat modeling and risk assessment frameworks, particularly focusing on the need for robust code signing and integrity verification processes in all system components that handle software updates. The vulnerability underscores the necessity of applying defense-in-depth strategies that protect not only the software components themselves but also the update mechanisms that govern how these components are modified or replaced.