CVE-2021-46145 in Civic
Summary
by MITRE • 01/06/2022
The keyfob subsystem in Honda Civic 2012 vehicles allows a replay attack for unlocking. This is related to a non-expiring rolling code and counter resynchronization.
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Analysis
by VulDB Data Team • 01/09/2022
The vulnerability identified as CVE-2021-46145 affects the keyfob subsystem of Honda Civic 2012 vehicles, representing a significant security flaw in the vehicle's access control mechanism. This issue stems from the implementation of a non-expiring rolling code system that fails to properly manage the cryptographic sequence used for vehicle authentication. The rolling code mechanism is designed to prevent replay attacks by incrementing a counter with each legitimate keyfob command, ensuring that previously used codes cannot be reused. However, in affected Honda Civic models, this counter resynchronization process is flawed, allowing malicious actors to capture and replay valid authentication sequences indefinitely.
The technical implementation of this vulnerability exposes a critical weakness in the automotive cybersecurity framework where the rolling code algorithm lacks proper expiration mechanisms and robust counter management. The non-expiring rolling code creates a persistent window of opportunity for attackers to record legitimate keyfob communications and subsequently replay them to gain unauthorized vehicle access. This flaw directly relates to CWE-327, which addresses the use of weak cryptographic algorithms and improper implementation of cryptographic functions. The counter resynchronization issue indicates a failure in maintaining proper state management within the authentication protocol, enabling attackers to manipulate the sequence counter to bypass security checks.
Operationally, this vulnerability presents a severe risk to vehicle owners as it allows for unauthorized access to vehicles without requiring physical possession of the keyfob or knowledge of the user's personal information. The replay attack capability means that an attacker with access to a captured signal can potentially unlock and gain entry to the vehicle at any time, even after the legitimate user has moved away from the vehicle. This creates a persistent threat vector that remains active until the underlying software flaw is addressed, making it particularly concerning for automotive security standards. The vulnerability impacts both the physical security of the vehicle and the potential for theft of personal belongings stored within.
Mitigation strategies for this vulnerability should focus on implementing proper counter synchronization mechanisms and ensuring that rolling codes have appropriate expiration intervals to prevent replay attacks. Vehicle manufacturers should consider updating the keyfob subsystem firmware to correct the counter resynchronization issue and implement stronger cryptographic protocols that prevent the reuse of previously transmitted codes. The remediation process must address the fundamental design flaw in the rolling code implementation while maintaining compatibility with existing keyfob hardware. Security measures should align with automotive industry standards such as ISO/SAE 21434 for cybersecurity and may require hardware-level modifications to ensure proper counter management and code expiration. Organizations implementing automotive security frameworks should consider this vulnerability as a critical risk requiring immediate attention and remediation to protect vehicle owners from potential unauthorized access.