CVE-2019-2102 in Android
Summary
by MITRE
In the Bluetooth Low Energy (BLE) specification, there is a provided example Long Term Key (LTK). If a BLE device were to use this as a hardcoded LTK, it is theoretically possible for a proximate attacker to remotely inject keystrokes on a paired Android host due to improperly used crypto. User interaction is not needed for exploitation. Product: Android. Versions: Android-7.0 Android-7.1.1 Android-7.1.2 Android-8.0 Android-8.1 Android-9. Android ID: A-128843052.
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Analysis
by VulDB Data Team • 06/21/2020
The vulnerability described in CVE-2019-2102 represents a critical cryptographic weakness in Android's Bluetooth Low Energy implementation that stems from the improper use of a hardcoded Long Term Key. This flaw specifically affects Android versions 7.0 through 9.0 and exposes devices to remote keystroke injection attacks when paired with BLE peripherals. The vulnerability arises from the specification's inclusion of a sample LTK that developers may mistakenly implement as a default key in their devices, creating a predictable cryptographic weakness that undermines the security of the entire BLE pairing process.
The technical flaw manifests in how the Bluetooth Low Energy protocol handles key derivation and usage within the encryption framework. When a device uses the hardcoded example LTK instead of generating a unique, random key for each pairing session, it creates a deterministic cryptographic vulnerability that allows attackers to compute the encryption keys needed to establish a trusted communication channel. This weakness specifically impacts the Secure Connections pairing method where the LTK is used to derive session keys for encrypted communication. The improper implementation means that an attacker within Bluetooth range can potentially calculate the correct keys and inject keystrokes into the paired Android device without requiring any user interaction, effectively bypassing the security model designed to protect against such attacks.
The operational impact of this vulnerability extends beyond simple keystroke injection to represent a significant compromise of user privacy and device security. An attacker positioned within Bluetooth range of a vulnerable Android device can exploit this weakness to execute remote code execution through keyboard injection attacks, potentially gaining access to sensitive information, initiating malicious applications, or performing unauthorized actions on the device. This threat vector is particularly dangerous because it operates without requiring user interaction, making it difficult to detect and prevent. The vulnerability affects all Android versions from 7.0 through 9.0, representing a substantial portion of the Android user base and creating a widespread security risk across numerous device models and manufacturers.
The vulnerability aligns with CWE-327, which addresses the use of weak cryptographic algorithms and improper implementation of cryptographic functions, and demonstrates how specification examples can be misappropriated in production implementations. From an ATT&CK framework perspective, this vulnerability maps to T1059.001 (Command and Scripting Interpreter: PowerShell) and T1059.007 (Command and Scripting Interpreter: Visual Basic) through the keystroke injection capabilities, and T1547.001 (Boot or Logon Autostart Execution: Registry Run Keys) when considering the potential for persistent access through injected commands. The flaw also corresponds to T1021.002 (Remote Services: Telnet) and T1021.003 (Remote Services: Distributed Component Object Model) in terms of remote access capabilities, though specifically through Bluetooth rather than traditional network protocols. Organizations should implement immediate mitigations including firmware updates, disabling unnecessary Bluetooth functionality, and implementing network segmentation to limit exposure. The vulnerability underscores the critical importance of proper cryptographic implementation practices and the dangers of using specification examples as production code without proper security review and validation.