CVE-2020-0159 in Android
Summary
by MITRE
In rw_mfc_writeBlock of rw_mfc.cc, there is a possible out of bounds read due to an incorrect bounds check. This could lead to local information disclosure with System execution privileges needed. User interaction is needed for exploitation.Product: AndroidVersions: Android-10Android ID: A-140768035
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Analysis
by VulDB Data Team • 06/12/2020
The vulnerability identified as CVE-2020-0159 resides within the Android system's NFC (Near Field Communication) subsystem, specifically in the rw_mfc_writeBlock function located in the rw_mfc.cc source file. This flaw represents a classic out-of-bounds read condition that occurs when the system performs incorrect bounds checking during NFC memory operations. The vulnerability is classified under CWE-129 as an Improper Validation of Array Index, which directly relates to the insufficient validation of memory access boundaries. The issue manifests when the Android system processes NFC memory write operations, particularly those involving MIFARE Classic cards which are commonly used in access control systems and contactless payment applications.
The technical implementation of this vulnerability stems from a flaw in the memory validation logic within the NFC stack's memory management component. When the rw_mfc_writeBlock function processes incoming data for writing to NFC memory blocks, it fails to properly validate the boundaries of the memory access operation. This incorrect bounds checking allows an attacker to potentially read memory locations beyond the intended buffer boundaries. The vulnerability requires system execution privileges to exploit, indicating that it operates at a privileged level within the Android operating system, likely within the NFC service or HAL (Hardware Abstraction Layer). The fact that user interaction is required for exploitation suggests that a malicious actor would need to initiate an NFC transaction or provide specific input that triggers the vulnerable code path.
The operational impact of this vulnerability extends beyond simple information disclosure, as it could potentially enable attackers to extract sensitive data from the device's memory. In the context of Android security, this type of local information disclosure could expose cryptographic keys, authentication tokens, or other sensitive system data that might be stored in adjacent memory regions. The vulnerability affects Android 10 systems and is tracked under Android ID A-140768035, indicating it was properly catalogued within Google's internal vulnerability tracking system. From an ATT&CK framework perspective, this vulnerability aligns with techniques such as T1059.001 (Command and Scripting Interpreter: PowerShell) and T1003 (Credential Dumping) when exploited by malicious actors who can leverage the information disclosure to gain deeper access to system resources. The local nature of the exploitation requirement means that physical proximity to the target device is typically necessary, though the system privilege requirement suggests that even a compromised user account could potentially leverage this vulnerability.
Mitigation strategies for CVE-2020-0159 should focus on both immediate patching and defensive measures. Android device manufacturers and carriers should prioritize the deployment of security updates that correct the bounds checking logic in the NFC subsystem. The fix typically involves implementing proper array index validation before any memory access operations occur, ensuring that all memory access boundaries are properly validated against the actual allocated buffer sizes. Organizations should also consider implementing NFC access controls and monitoring for unusual NFC activity patterns that might indicate exploitation attempts. Additionally, security teams should review their incident response procedures to ensure they can quickly detect and respond to potential exploitation attempts targeting NFC subsystem vulnerabilities. The vulnerability's classification as a local information disclosure means that physical security measures should also be considered, particularly in environments where NFC-enabled devices are used for sensitive applications such as access control or financial transactions.