CVE-2015-8613 in QEMU
Summary
by MITRE
Stack-based buffer overflow in the megasas_ctrl_get_info function in QEMU, when built with SCSI MegaRAID SAS HBA emulation support, allows local guest users to cause a denial of service (QEMU instance crash) via a crafted SCSI controller CTRL_GET_INFO command.
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Analysis
by VulDB Data Team • 08/29/2020
The vulnerability CVE-2015-8613 represents a stack-based buffer overflow in QEMU's megasas_ctrl_get_info function that occurs when the virtualization platform is compiled with SCSI MegaRAID SAS HBA emulation support. This flaw exists within the virtual machine monitoring software that emulates storage hardware for guest operating systems, creating a critical security risk in virtualized environments where multiple users or processes interact with the hypervisor. The vulnerability specifically targets the management interface of the MegaRAID SAS HBA controller emulation, which is commonly used in enterprise virtualization deployments to provide storage functionality to virtual machines.
The technical implementation of this vulnerability stems from improper bounds checking within the megasas_ctrl_get_info function, which processes SCSI controller commands sent from guest operating systems. When a malicious guest user crafts a specially formatted CTRL_GET_INFO command, the function fails to validate the size of incoming data before copying it to a fixed-size stack buffer. This classic buffer overflow condition allows an attacker to overwrite adjacent stack memory, potentially corrupting program execution flow and causing the QEMU instance to crash. The vulnerability is classified as CWE-121 Stack-based Buffer Overflow, which is a well-documented weakness in software security that occurs when data is copied to a stack buffer without proper size validation.
The operational impact of this vulnerability extends beyond simple denial of service, as it can be exploited to compromise the stability and availability of virtualized environments. Local guest users who have access to the virtual machine can leverage this flaw to crash the QEMU process, effectively terminating the virtual machine instance and potentially disrupting services running within it. In enterprise environments where multiple virtual machines share the same hypervisor host, such an attack could lead to cascading failures and significant service disruption. The vulnerability demonstrates a fundamental flaw in privilege separation within virtualization platforms, where guest users can affect the host system's stability through crafted commands.
Mitigation strategies for CVE-2015-8613 should focus on immediate patching of affected QEMU versions, which typically involves updating to versions that contain proper bounds checking in the affected function. System administrators should also implement network segmentation and access controls to limit guest user privileges, reducing the attack surface available to potential exploiters. Additional defensive measures include monitoring for unusual SCSI command patterns and implementing intrusion detection systems that can identify crafted CTRL_GET_INFO commands. The vulnerability aligns with ATT&CK technique T1059.001 Command and Scripting Interpreter: PowerShell, as it involves crafting specific command sequences to exploit the buffer overflow. Organizations should also consider implementing virtual machine isolation measures and regular security audits of their virtualization infrastructure to prevent similar vulnerabilities from being exploited in production environments.