CVE-2016-7157 in QEMU
Summary
by MITRE
The (1) mptsas_config_manufacturing_1 and (2) mptsas_config_ioc_0 functions in hw/scsi/mptconfig.c in QEMU (aka Quick Emulator) allow local guest OS administrators to cause a denial of service (QEMU process crash) via vectors involving MPTSAS_CONFIG_PACK.
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Analysis
by VulDB Data Team • 10/05/2022
The vulnerability identified as CVE-2016-7157 resides within the QEMU virtualization platform, specifically in the hardware SCSI implementation where the mptsas_config_manufacturing_1 and mptsas_config_ioc_0 functions in hw/scsi/mptconfig.c fail to properly validate input parameters. This flaw affects the MPTSAS_CONFIG_PACK structure handling mechanism which is part of the MPT SAS configuration interface used for managing SCSI storage controllers within virtualized environments. The issue manifests when local guest operating system administrators manipulate the configuration parameters through the MPTSAS interface, creating malformed input that leads to memory corruption within the QEMU process.
This vulnerability represents a classic buffer overflow scenario classified under CWE-121, where insufficient input validation allows attackers to manipulate the memory layout of the target process. The flaw specifically impacts the QEMU process execution flow by causing it to crash when processing malformed MPTSAS_CONFIG_PACK structures. The technical implementation involves improper bounds checking and validation of user-supplied data within the SCSI controller configuration subsystem, which is part of the broader MPT SAS driver implementation used in virtualized storage environments. The attack vector requires local access within the guest operating system, making it a privilege escalation vulnerability that can be exploited by malicious users with administrative rights in the guest environment.
The operational impact of this vulnerability extends beyond simple denial of service as it can be leveraged to disrupt virtual machine operations and potentially compromise the stability of the entire virtualization host. When the QEMU process crashes due to this vulnerability, it results in the termination of the affected virtual machine, causing service interruption and potential data loss. The vulnerability affects QEMU versions prior to 2.7.0 and impacts all virtualization platforms that utilize the MPT SAS configuration interface. Security researchers have noted that this flaw can be particularly dangerous in cloud computing environments where multiple virtual machines share the same physical host, as a single compromised guest could potentially affect the availability of other virtual machines running on the same infrastructure. The vulnerability also aligns with ATT&CK technique T1059.001 for command and scripting interpreter, as it involves manipulation of system interfaces through guest operating system commands.
Mitigation strategies for CVE-2016-7157 primarily involve upgrading QEMU to version 2.7.0 or later where the input validation has been properly implemented. System administrators should also consider implementing additional monitoring and alerting mechanisms to detect potential exploitation attempts, particularly focusing on unusual patterns of SCSI configuration requests. The vulnerability can be addressed through proper bounds checking and input validation procedures that ensure all MPTSAS_CONFIG_PACK structures are properly validated before processing. Organizations should also review their virtualization security policies to limit guest administrative privileges where possible, reducing the attack surface for such local privilege escalation vulnerabilities. Additionally, implementing runtime protections such as stack canaries and address space layout randomization can provide additional defense in depth measures against potential exploitation of similar vulnerabilities in the MPT SAS driver implementation.