CVE-2016-1714 in QEMU
Summary
by MITRE
The (1) fw_cfg_write and (2) fw_cfg_read functions in hw/nvram/fw_cfg.c in QEMU before 2.4, when built with the Firmware Configuration device emulation support, allow guest OS users with the CAP_SYS_RAWIO privilege to cause a denial of service (out-of-bounds read or write access and process crash) or possibly execute arbitrary code via an invalid current entry value in a firmware configuration.
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Analysis
by VulDB Data Team • 07/06/2022
The vulnerability identified as CVE-2016-1714 represents a critical security flaw in QEMU's firmware configuration device emulation functionality, specifically affecting versions prior to 2.4. This issue resides within the fw_cfg_write and fw_cfg_read functions located in the hw/nvram/fw_cfg.c file, which are responsible for managing firmware configuration operations within virtualized environments. The vulnerability stems from inadequate validation of the current entry value during firmware configuration operations, creating a potential attack vector that could be exploited by malicious actors within the guest operating system.
The technical flaw manifests as a lack of proper bounds checking and input validation in the firmware configuration device implementation. When QEMU is compiled with Firmware Configuration device emulation support, guest operating systems with the CAP_SYS_RAWIO privilege can manipulate the firmware configuration entries through the vulnerable functions. This privilege allows processes to bypass normal access controls and directly interact with hardware devices, making the guest environment a potential attack surface for privilege escalation. The absence of validation for the current entry value enables attackers to specify invalid memory addresses that fall outside the legitimate firmware configuration boundaries, leading to out-of-bounds read or write operations.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, potentially enabling arbitrary code execution within the virtualized environment. An attacker with sufficient privileges in the guest OS can leverage this flaw to corrupt memory regions, cause process crashes, or even execute malicious code with the privileges of the QEMU process. This represents a significant escalation risk since QEMU typically runs with elevated privileges to manage virtual hardware, and any compromise of the hypervisor layer can affect the entire virtualization infrastructure. The vulnerability affects the integrity and confidentiality of virtual machine operations, potentially allowing attackers to access sensitive data or manipulate the virtual environment in ways that could compromise other virtual machines running on the same host.
The vulnerability maps directly to CWE-125: "Out-of-bounds Read" and CWE-787: "Out-of-bounds Write" within the Common Weakness Enumeration framework, highlighting the fundamental memory safety issues in the firmware configuration implementation. From an adversarial perspective, this vulnerability aligns with ATT&CK technique T1055: "Process Injection" and T1068: "Exploitation for Privilege Escalation" as attackers could exploit the out-of-bounds memory access to escalate privileges within the guest environment and potentially gain control over the host system. Mitigation strategies should include immediate patching to QEMU version 2.4 or later, where proper bounds checking and input validation have been implemented. Additional protective measures include restricting CAP_SYS_RAWIO privileges for guest operating systems, implementing network segmentation, and monitoring for unusual memory access patterns that might indicate exploitation attempts. Organizations should also consider implementing hypervisor-level security controls and regular vulnerability assessments to identify similar issues in other virtualization components.