CVE-2013-6399 in QEMU
Summary
by MITRE
Array index error in the virtio_load function in hw/virtio/virtio.c in QEMU before 1.7.2 allows remote attackers to execute arbitrary code via a crafted savevm image.
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Analysis
by VulDB Data Team • 06/20/2021
The vulnerability identified as CVE-2013-6399 represents a critical array index error within the virtio_load function of QEMU's virtualization subsystem. This flaw exists in the hw/virtio/virtio.c file and affects QEMU versions prior to 1.7.2, creating a significant security risk for virtualized environments. The vulnerability stems from inadequate input validation when processing savevm images, which are used to serialize and restore virtual machine states during migration or snapshot operations.
The technical nature of this vulnerability classifies it as a buffer over-read condition that occurs during the virtio device state restoration process. When QEMU attempts to load a savevm image containing maliciously crafted data, the virtio_load function fails to properly validate array indices, allowing an attacker to bypass normal bounds checking mechanisms. This misconfiguration enables an attacker to manipulate memory access patterns and potentially execute arbitrary code with the privileges of the QEMU process. The flaw operates at the virtualization layer where guest operating systems interact with virtualized hardware components, making it particularly dangerous for cloud computing environments where multiple tenants share the same hypervisor infrastructure.
From an operational perspective, this vulnerability poses severe risks to virtualized infrastructures as it allows remote code execution without requiring authentication or direct access to the target system. Attackers can exploit this weakness by crafting specially designed savevm images that, when loaded by a vulnerable QEMU instance, trigger the buffer over-read condition. The impact extends beyond individual virtual machines to potentially compromise the entire host system, as successful exploitation could lead to privilege escalation and lateral movement within the virtualized environment. This vulnerability directly relates to CWE-129 Input Validation and Output Encoding, specifically addressing improper validation of array indices and insufficient bounds checking. The ATT&CK framework categorizes this vulnerability under T1059 Command and Scripting Interpreter and T1068 Exploitation for Privilege Escalation, as it enables attackers to execute code and potentially elevate their privileges within the virtualized environment.
The exploitation of this vulnerability requires minimal prerequisites since savevm images can be transmitted over network connections or stored in shared storage systems, making it particularly dangerous in multi-tenant cloud environments. Organizations utilizing QEMU-based virtualization platforms must urgently implement mitigations including immediate patching to version 1.7.2 or later, implementing network segmentation to prevent unauthorized access to virtualization management interfaces, and monitoring for suspicious savevm image loading activities. Additionally, virtual machine images should be validated and sanitized before importing into production environments, and access controls should be enforced to limit who can initiate virtual machine state restoration operations. The vulnerability demonstrates the critical importance of proper memory management and input validation in virtualization software, as even seemingly benign operations like state restoration can become attack vectors when proper bounds checking mechanisms are absent.