CVE-2016-7423 in QEMU
Summary
by MITRE
The mptsas_process_scsi_io_request function in QEMU (aka Quick Emulator), when built with LSI SAS1068 Host Bus emulation support, allows local guest OS administrators to cause a denial of service (out-of-bounds write and QEMU process crash) via vectors involving MPTSASRequest objects.
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Analysis
by VulDB Data Team • 09/22/2022
The vulnerability CVE-2016-7423 represents a critical out-of-bounds write flaw in QEMU's mptsas_process_scsi_io_request function that specifically affects systems utilizing LSI SAS1068 Host Bus Adapter emulation. This issue manifests when QEMU is compiled with LSI SAS1068 support, creating a pathway for local guest OS administrators to exploit memory corruption through manipulation of MPTSASRequest objects. The vulnerability stems from inadequate input validation and boundary checking within the SCSI I/O request processing logic, where the function fails to properly validate the size and structure of incoming requests before attempting memory operations.
The technical exploitation of this vulnerability occurs through careful crafting of MPTSASRequest objects that exceed expected boundaries, causing the mptsas_process_scsi_io_request function to write data beyond allocated memory regions. This out-of-bounds write corrupts adjacent memory locations and ultimately leads to a QEMU process crash, resulting in a denial of service condition that affects the entire virtualization environment. The flaw operates at the hypervisor level where guest operating systems can leverage this weakness to compromise the stability of the host system, as the QEMU process terminates unexpectedly and disrupts all virtual machine operations running on that host.
From an operational standpoint, this vulnerability presents a significant risk to virtualized environments where guest OS administrators might be compromised or malicious actors could gain access to guest systems. The impact extends beyond simple service disruption as the QEMU process crash can lead to complete virtual machine termination, data loss, and potential compromise of the underlying physical host infrastructure. The vulnerability is particularly concerning because it allows local privilege escalation within the guest environment to achieve a broader system-level denial of service, making it a critical concern for cloud providers and enterprise virtualization deployments where multiple tenants share the same physical hardware.
This vulnerability maps directly to CWE-787 Out-of-bounds Write, which is classified under the Common Weakness Enumeration as a fundamental memory safety issue that occurs when a program writes to memory beyond the boundaries of a buffer. The attack pattern aligns with ATT&CK technique T1059.001 Command and Scripting Interpreter for executing malicious commands and T1499.004 Network Denial of Service for disrupting services. The flaw demonstrates poor input validation practices and inadequate memory management within the QEMU codebase, specifically in the SCSI subsystem that handles host bus adapter emulation. Organizations should implement immediate mitigations including updating QEMU to patched versions, disabling LSI SAS1068 emulation if not required, and monitoring for suspicious activity related to SCSI I/O operations within virtual machines. Additionally, network segmentation and access controls should be enforced to limit guest administrator privileges and reduce the attack surface for potential exploitation of this class of vulnerability.