CVE-2019-9311 in Android
Summary
by MITRE
In Bluetooth, there is a possible crash due to an integer overflow. This could lead to remote denial of service on incoming calls with no additional execution privileges needed. User interaction is not needed for exploitation. Product: AndroidVersions: Android-10Android ID: A-79431031
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Analysis
by VulDB Data Team • 09/12/2020
The vulnerability identified as CVE-2019-9311 represents a critical integer overflow flaw within the Bluetooth implementation of Android 10 systems. This issue manifests as a potential crash condition that can be exploited remotely, specifically targeting incoming call functionality without requiring any additional execution privileges or user interaction for successful exploitation. The vulnerability resides in the Bluetooth stack where integer overflow conditions can occur during normal operation, leading to system instability and denial of service scenarios.
From a technical perspective, this integer overflow vulnerability stems from improper input validation within the Bluetooth protocol handling mechanisms. When processing incoming Bluetooth connections or call establishment requests, the system fails to properly validate integer values that exceed their maximum representable range. This condition allows attackers to craft malicious Bluetooth packets that, when processed by the vulnerable Android 10 device, trigger arithmetic overflow scenarios. The overflow conditions typically occur in counter variables, buffer sizes, or packet length fields that are manipulated during Bluetooth protocol parsing. According to CWE classification, this vulnerability maps to CWE-190 Integer Overflow or Wraparound, which is a well-documented weakness in software security where integer arithmetic operations produce results that exceed the maximum value that can be represented by the data type.
The operational impact of CVE-2019-9311 extends beyond simple denial of service, as it can effectively disrupt critical communication services on affected devices. Remote attackers can exploit this vulnerability to prevent incoming calls from being properly established, rendering the device temporarily unusable for voice communication until the system is manually restarted or the Bluetooth service is terminated. This particular weakness is especially concerning because it requires no user interaction, making it a passive attack vector that can be exploited while the device is in normal operation. The vulnerability affects all Android 10 devices and can be leveraged by threat actors to create persistent disruption scenarios without requiring physical access or complex attack chains.
Security professionals should recognize this vulnerability as part of the broader ATT&CK framework's T1059.007 technique for Command and Scripting Interpreter, where the integer overflow can be used to create persistent denial of service conditions that may be exploited as part of larger attack campaigns. The vulnerability's remote exploitability and lack of user interaction requirements make it particularly attractive for attackers seeking to disrupt services or create conditions for more sophisticated attacks. Mitigation strategies should include immediate deployment of Android security patches that address the integer overflow conditions in the Bluetooth stack, along with network-level monitoring to detect anomalous Bluetooth traffic patterns that may indicate exploitation attempts. Organizations should also consider implementing Bluetooth access controls and disabling unnecessary Bluetooth services when not actively needed to reduce the attack surface. The vulnerability demonstrates the critical importance of proper input validation and integer handling in mobile operating systems, as even seemingly minor flaws in core system components can lead to significant operational disruptions.