CVE-2016-5105 in QEMU
Summary
by MITRE
The megasas_dcmd_cfg_read function in hw/scsi/megasas.c in QEMU, when built with MegaRAID SAS 8708EM2 Host Bus Adapter emulation support, uses an uninitialized variable, which allows local guest administrators to read host memory via vectors involving a MegaRAID Firmware Interface (MFI) command.
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Analysis
by VulDB Data Team • 09/14/2022
The vulnerability identified as CVE-2016-5105 represents a critical security flaw within the QEMU virtualization platform that specifically affects systems utilizing MegaRAID SAS 8708EM2 Host Bus Adapter emulation capabilities. This issue stems from improper initialization of variables within the megasas_dcmd_cfg_read function located in the hw/scsi/megasas.c source file, creating a potential pathway for unauthorized memory access that could be exploited by malicious actors within the guest operating system environment. The flaw manifests when QEMU is compiled with MegaRAID SAS 8708EM2 Host Bus Adapter emulation support, making it particularly concerning for virtualized environments that rely on this specific storage controller emulation.
The technical implementation of this vulnerability involves the megasas_dcmd_cfg_read function failing to properly initialize a variable before utilizing its contents in memory operations. This uninitialized variable contains unpredictable data from previous memory operations, which then gets processed through the MegaRAID Firmware Interface (MFI) command vectors. When local guest administrators execute specific commands through the emulated storage controller, they can leverage this uninitialized variable to craft memory read operations that traverse into host memory space. The MFI command interface serves as the communication pathway between the guest operating system and the emulated storage controller, making it a prime target for exploitation.
The operational impact of CVE-2016-5105 extends beyond simple information disclosure, as it creates a persistent threat vector that allows attackers with local administrative privileges in the guest environment to potentially access sensitive data residing in host memory. This vulnerability fundamentally undermines the isolation guarantees that virtualization platforms are designed to provide, enabling a form of privilege escalation that operates at the hypervisor level. Attackers could potentially extract confidential information, system configuration details, or other sensitive data that should remain isolated between guest and host environments. The implications are particularly severe in multi-tenant cloud environments where guest administrators might exploit this vulnerability to access data belonging to other customers.
From a cybersecurity perspective, this vulnerability aligns with CWE-457, which addresses the use of uninitialized variables, and demonstrates characteristics consistent with ATT&CK technique T1059.001 for command and scripting interpreter usage. The flaw represents a classic case of information leakage through improper memory handling that could be exploited to bypass virtualization security boundaries. Mitigation strategies should include immediate patching of affected QEMU versions, disabling MegaRAID SAS 8708EM2 Host Bus Adapter emulation when not required, and implementing strict access controls within guest operating systems to minimize the attack surface. Additionally, organizations should consider network segmentation and monitoring for unusual memory access patterns that could indicate exploitation attempts, as the vulnerability requires local guest administrator privileges to exploit but can potentially provide extensive host memory access capabilities.