CVE-2018-19665 in QEMU
Summary
by MITRE
The Bluetooth subsystem in QEMU mishandles negative values for length variables, leading to memory corruption.
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Analysis
by VulDB Data Team • 04/18/2020
The vulnerability identified as CVE-2018-19665 resides within the Bluetooth subsystem of QEMU virtualization software, representing a critical memory corruption issue that stems from improper handling of negative length values. This flaw exists in the hypervisor environment where QEMU serves as a widely deployed virtualization platform for various operating systems and hardware configurations. The vulnerability specifically manifests when the Bluetooth implementation processes length parameters that contain negative values, which should never occur in legitimate Bluetooth protocol communications but can be exploited through crafted malicious inputs.
The technical root cause of this vulnerability aligns with CWE-128, which addresses "Wrap or Overflow" conditions in integer handling, and more specifically relates to CWE-129, "Improper Validation of Array Index." The flaw occurs because the Bluetooth subsystem fails to validate that length parameters remain within acceptable positive bounds before using them in memory allocation or buffer operations. When negative values are processed, they can cause integer underflow conditions that result in unexpected memory access patterns, potentially leading to heap corruption, stack corruption, or arbitrary code execution. This type of vulnerability falls under the ATT&CK technique T1059.007 for "Command and Scripting Interpreter: PowerShell" and T1059.001 for "Command and Scripting Interpreter: JavaScript" when considering how attackers might exploit such memory corruption to execute malicious code within the virtualized environment.
The operational impact of CVE-2018-19665 extends beyond simple memory corruption, as it represents a potential path to complete system compromise within virtualized environments. Attackers could leverage this vulnerability to execute arbitrary code with the privileges of the QEMU process, which typically runs with elevated permissions to manage virtual machine operations. In cloud computing and enterprise virtualization deployments where QEMU is extensively used, this vulnerability could enable attackers to escape virtual machine boundaries and potentially compromise the host system or other virtual machines running on the same infrastructure. The vulnerability's exploitation potential increases significantly in environments where virtual machines are configured with Bluetooth passthrough capabilities or where Bluetooth devices are emulated within the virtual environment.
Mitigation strategies for CVE-2018-19665 should prioritize immediate patching of QEMU installations to the latest versions that contain the necessary fixes for the Bluetooth subsystem. Organizations should also implement network segmentation and access controls to limit exposure of Bluetooth functionality within virtualized environments where possible. The vulnerability highlights the importance of proper input validation and integer overflow protection in virtualization software components, as outlined in security standards such as those defined by the Common Weakness Enumeration and the MITRE ATT&CK framework. Additional defensive measures include monitoring for anomalous Bluetooth protocol behavior, implementing memory protection mechanisms such as stack canaries and address space layout randomization, and conducting regular security assessments of virtualization environments to identify similar vulnerabilities in other subsystems.