CVE-2024-53845 in ESP-IDF
Summary
by MITRE • 12/12/2024
ESPTouch is a connection protocol for internet of things devices. In the ESPTouchV2 protocol, while there is an option to use a custom AES key, there is no option to set the IV (Initialization Vector) prior to versions 5.3.2, 5.2.4, 5.1.6, and 5.0.8. The IV is set to zero and remains constant throughout the product's lifetime. In AES/CBC mode, if the IV is not properly initialized, the encrypted output becomes deterministic, leading to potential data leakage. To address the aforementioned issues, the application generates a random IV when activating the AES key starting in versions 5.3.2, 5.2.4, 5.1.6, and 5.0.8. This IV is then transmitted along with the provision data to the provision device. The provision device has also been equipped with a parser for the AES IV. The upgrade is applicable for all applications and users of ESPTouch v2 component from ESP-IDF. As it is implemented in the ESP Wi-Fi stack, there is no workaround for the user to fix the application layer without upgrading the underlying firmware.
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Analysis
by VulDB Data Team • 12/12/2024
The ESPTouch protocol represents a critical connectivity framework for internet of things devices, enabling seamless network configuration and provisioning of embedded systems. This protocol operates within the ESP-IDF ecosystem and serves as a foundational component for wireless device management in IoT deployments. The vulnerability identified in ESPTouchV2 protocol stems from improper implementation of cryptographic parameters, specifically the initialization vector handling within AES encryption operations. The protocol's design flaw becomes particularly significant when considering that many IoT devices rely on this standardized provisioning mechanism for secure network establishment and device management.
The technical vulnerability manifests in the deterministic nature of AES/CBC encryption operations due to the constant zero initialization vector. When an IV is set to zero and remains static throughout the product lifecycle, it fundamentally compromises the security guarantees inherent to CBC mode encryption. This deterministic behavior creates predictable ciphertext patterns that can be exploited by adversaries to infer sensitive information about the encrypted data. The absence of proper IV initialization directly violates established cryptographic best practices and represents a clear violation of the principle that initialization vectors must be unique and unpredictable for each encryption operation. This vulnerability is classified under CWE-329 which specifically addresses the lack of entropy in cryptographic operations and aligns with ATT&CK technique T1552.001 related to credentials in files and T1552.006 for unsecured cryptographic keys.
The operational impact of this vulnerability extends across numerous IoT deployments where ESPTouchV2 protocol is implemented, potentially exposing sensitive provisioning data to various attack vectors. When the IV remains constant at zero, attackers can perform pattern analysis on encrypted communications, potentially reconstructing sensitive information such as device identifiers, network credentials, or configuration parameters. The deterministic encryption behavior creates a scenario where identical plaintext messages produce identical ciphertext outputs, undermining the core security properties of encryption. This vulnerability affects all versions prior to 5.3.2, 5.2.4, 5.1.6, and 5.0.8, representing a widespread issue across multiple release branches of the ESP-IDF framework. The attack surface is particularly concerning given that many IoT devices depend on this provisioning mechanism for initial network setup and ongoing device management.
The remediation implemented in versions 5.3.2, 5.2.4, 5.1.6, and 5.0.8 addresses the core issue by introducing proper random IV generation during AES key activation. This solution ensures that each encryption operation uses a unique initialization vector, eliminating the deterministic behavior that previously existed. The fix requires the application to generate a random IV upon activation of the AES key and transmit this IV alongside the provisioning data to the target device. The provision device must also be updated to properly parse and utilize the transmitted IV, ensuring end-to-end cryptographic integrity. This approach aligns with established cryptographic standards and represents a fundamental improvement in the security posture of the ESPTouch protocol. The upgrade mechanism is comprehensive, covering all applications and users of the ESPTouch v2 component within ESP-IDF, though it requires firmware-level changes that cannot be bypassed at the application layer. This limitation underscores the importance of proper dependency management and security patching in embedded systems development, where the underlying framework security directly impacts application-level functionality and protection.