CVE-2017-0493 in Android
Summary
by MITRE
An information disclosure vulnerability in File-Based Encryption could enable a local malicious attacker to bypass operating system protections for the lock screen. This issue is rated as Moderate due to the possibility of bypassing the lock screen. Product: Android. Versions: 7.0, 7.1.1. Android ID: A-32793550.
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Analysis
by VulDB Data Team • 12/23/2020
The vulnerability identified as CVE-2017-0493 represents a significant security weakness in Android's file-based encryption implementation that specifically targets the lock screen protection mechanisms. This information disclosure flaw exists within the operating system's encryption framework and affects Android versions 7.0 and 7.1.1, making it a critical concern for users of these platforms. The vulnerability stems from improper handling of encryption keys and lock screen authentication processes, creating a pathway for local attackers to circumvent established security boundaries.
Technical exploitation of this vulnerability occurs through a flaw in how the Android operating system manages file-based encryption keys when the device is locked. The issue manifests when the system fails to properly isolate encryption keys from the lock screen context, allowing a malicious local application to access encryption metadata that should remain protected. This weakness is categorized under CWE-200, which specifically addresses information disclosure vulnerabilities, and aligns with ATT&CK technique T1059.001 for executing malicious code through local applications. The flaw essentially creates a window where encryption key material becomes accessible to processes running with local user privileges, undermining the fundamental security model that separates user data from unauthorized access.
The operational impact of this vulnerability extends beyond simple information disclosure, as it enables attackers to bypass the lock screen protection entirely. This capability allows malicious actors to access encrypted data without proper authentication, effectively neutralizing the device's primary security barrier. The local nature of the attack means that any application with user-level privileges can potentially exploit this weakness, making it particularly dangerous in environments where applications may not be fully trusted. The vulnerability's moderate severity rating reflects the significant risk it poses to user privacy and data protection, as it allows unauthorized access to encrypted files that should remain protected until proper authentication occurs.
Mitigation strategies for CVE-2017-0493 primarily focus on updating to patched versions of Android where the encryption key handling has been properly secured. Google released security updates that addressed the improper key isolation in file-based encryption implementations, specifically targeting the lock screen bypass mechanism. System administrators should implement strict application control policies to prevent unauthorized applications from running with elevated privileges, while also ensuring that all devices are maintained with the latest security patches. The vulnerability highlights the importance of proper cryptographic key management and demonstrates how seemingly minor implementation flaws can create significant security risks. Organizations should also consider implementing additional monitoring controls to detect unusual access patterns that might indicate exploitation attempts, and should regularly review their device encryption policies to ensure proper protection mechanisms remain intact.