CVE-2019-9386 in Android
Summary
by MITRE
In NFC server, there is a possible out of bounds write due to a missing bounds check. This could lead to local escalation of privilege in the system server with no additional execution privileges needed. User interaction is needed for exploitation. Product: AndroidVersions: Android-10Android ID: A-122361874
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Analysis
by VulDB Data Team • 09/13/2020
The vulnerability identified as CVE-2019-9386 resides within the NFC server component of Android operating systems, specifically affecting Android 10 and earlier versions. This issue represents a critical security flaw that could potentially enable local privilege escalation without requiring additional execution privileges. The vulnerability manifests as an out-of-bounds write condition that occurs due to a missing bounds check within the NFC server implementation, making it a prime example of a memory safety issue that can be exploited to gain elevated system privileges.
The technical flaw in CVE-2019-9386 stems from insufficient input validation and bounds checking within the NFC server's processing logic. When the system receives NFC-related data, it fails to properly validate the size or boundaries of incoming data structures before writing to memory locations. This missing bounds check creates an opportunity for attackers to craft malicious NFC data that, when processed by the server, results in writing data beyond the allocated memory buffer. The vulnerability is classified under CWE-129 as "Improper Validation of Array Index" and falls within the broader category of memory corruption vulnerabilities that can lead to privilege escalation.
The operational impact of this vulnerability is significant as it enables local privilege escalation within the system server context. An attacker who can interact with the NFC subsystem can potentially exploit this flaw to gain elevated privileges without requiring additional execution privileges or user interaction beyond the initial NFC data reception. This represents a serious security risk because the NFC server typically operates with high privileges, and any vulnerability within this component can be leveraged to compromise the entire system. The requirement for user interaction to initiate exploitation means that social engineering or physical proximity attacks could be employed to deliver malicious NFC data.
Exploitation of CVE-2019-9386 aligns with ATT&CK technique T1068 which covers "Local Privilege Escalation" and specifically addresses the path to gaining elevated privileges through system service vulnerabilities. The attack surface for this vulnerability is primarily through NFC data transmission, making it particularly concerning for mobile devices where NFC functionality is commonly enabled and used. The vulnerability's classification as a local privilege escalation means that successful exploitation could allow an attacker to gain system-level access, potentially enabling them to install malicious applications, access sensitive data, or modify system configurations. The Android ID A-122361874 indicates this vulnerability was tracked within Google's internal security tracking system, highlighting its significance in the Android security landscape.
Mitigation strategies for CVE-2019-9386 should include immediate deployment of security patches provided by Google for Android 10 and earlier versions. System administrators should disable NFC functionality when not required and ensure that all devices are running the latest security updates. Additionally, implementing network segmentation and access controls can help reduce the attack surface, while monitoring for unusual NFC data processing patterns can aid in early detection of potential exploitation attempts. The vulnerability underscores the importance of robust input validation and bounds checking in system services, particularly those with elevated privileges, and serves as a reminder of the critical nature of memory safety in mobile operating systems.