CVE-2014-3471 in QEMU
Summary
by MITRE
Use-after-free vulnerability in hw/pci/pcie.c in QEMU (aka Quick Emulator) allows local guest OS users to cause a denial of service (QEMU instance crash) via hotplug and hotunplug operations of Virtio block devices.
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Analysis
by VulDB Data Team • 12/25/2024
The CVE-2014-3471 vulnerability represents a critical use-after-free flaw in the QEMU virtualization platform that specifically affects the PCI express device handling code in the hw/pci/pcie.c module. This vulnerability arises from improper memory management during hotplug and hotunplug operations of Virtio block devices within virtual machine environments, creating a scenario where freed memory regions are still accessed by subsequent operations. The flaw exists in the QEMU hypervisor implementation that manages virtual PCI express devices, making it particularly dangerous in virtualized environments where multiple guest operating systems may be running simultaneously.
The technical execution of this vulnerability occurs when a guest operating system performs a sequence of hotplug and hotunplug operations on Virtio block devices while QEMU manages the underlying PCI express hardware emulation. During these operations, the memory allocated to track device state becomes freed, but subsequent operations attempt to access this freed memory region without proper validation. This use-after-free condition manifests as a memory corruption error that ultimately leads to a segmentation fault or similar memory access violation, causing the QEMU instance to crash and terminate the virtual machine hosting the malicious guest OS. The vulnerability specifically targets the PCI express configuration space handling and device state management functions within QEMU's hardware emulation layer.
The operational impact of CVE-2014-3471 extends beyond simple denial of service, as it can be exploited to disrupt virtualized environments in production systems where QEMU serves as the primary hypervisor. Attackers with access to a guest operating system can leverage this vulnerability to crash the entire QEMU instance, potentially affecting multiple virtual machines running on the same host. This creates significant risk for cloud service providers, data centers, and enterprise environments that rely on QEMU for virtualization, as a single compromised guest could potentially cause cascading failures across multiple virtual machines. The vulnerability demonstrates the critical importance of proper memory management in hypervisor code, as even local guest users can achieve remote-like effects through carefully crafted device operations.
The vulnerability aligns with CWE-416, which describes the use of freed memory condition, and represents a classic example of improper resource management in virtualization software. From an ATT&CK framework perspective, this vulnerability could be categorized under privilege escalation and denial of service tactics, as it allows local guest users to execute actions that affect the host system's stability. Organizations should implement immediate mitigations including patching QEMU to version 2.1.0 or later, which addresses the memory management issues in the PCI express device handling code. Additional protective measures include implementing strict access controls on guest operating systems, monitoring for anomalous hotplug operations, and considering the use of alternative virtualization platforms where appropriate. System administrators should also consider implementing virtual machine isolation measures to prevent a single compromised guest from affecting other virtual machines on the same host, as the vulnerability could potentially be extended to more sophisticated attacks if combined with other exploitation techniques.