CVE-2014-7840 in QEMU
Summary
by MITRE
The host_from_stream_offset function in arch_init.c in QEMU, when loading RAM during migration, allows remote attackers to execute arbitrary code via a crafted (1) offset or (2) length value in savevm data.
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Analysis
by VulDB Data Team • 02/27/2022
The vulnerability described in CVE-2014-7840 resides within the QEMU virtualization platform's memory management subsystem, specifically in the arch_init.c file where the host_from_stream_offset function handles RAM loading operations during migration processes. This flaw represents a critical security issue that enables remote attackers to execute arbitrary code on systems running vulnerable QEMU versions. The vulnerability occurs during the savevm data processing phase when QEMU attempts to restore virtual machine state by loading RAM contents from migration streams. The function fails to properly validate offset and length parameters provided in the savevm data, creating a potential code execution vector that can be exploited by malicious actors.
The technical implementation of this vulnerability stems from inadequate input validation within the host_from_stream_offset function which processes stream offsets and lengths without sufficient bounds checking or sanitization. When QEMU receives migration data containing crafted offset or length values, the function processes these parameters directly without verifying their legitimacy or ensuring they remain within acceptable memory boundaries. This lack of validation creates a classic buffer overflow condition that can be leveraged to overwrite critical memory locations, potentially leading to arbitrary code execution. The vulnerability is particularly dangerous because it occurs during the migration process, which is a legitimate operational function that must be performed in production environments, making the attack surface more extensive than typical security flaws.
Operationally, this vulnerability poses significant risks to virtualized environments where QEMU is used for hosting multiple virtual machines. Attackers can exploit this flaw by sending specially crafted savevm data to a QEMU instance during migration operations, potentially gaining complete control over the host system. The impact extends beyond individual virtual machines to affect the entire host infrastructure, as successful exploitation could allow attackers to escalate privileges, access other VMs running on the same host, or even compromise the underlying physical hardware. This vulnerability particularly affects cloud computing environments, data centers, and any infrastructure relying on QEMU-based virtualization for their operations, making it a critical concern for security administrators and system operators.
Mitigation strategies for CVE-2014-7840 should focus on immediate patching of affected QEMU versions, with the implementation of proper input validation and bounds checking mechanisms. Organizations should ensure that all QEMU installations are updated to versions that address this vulnerability, typically those released after the vulnerability disclosure. Network segmentation and access controls should be implemented to limit exposure of QEMU migration endpoints to trusted networks only. The vulnerability aligns with CWE-129 Input Validation and Output Encoding, and can be mapped to ATT&CK technique T1059 Command and Scripting Interpreter for executing malicious code. Additionally, monitoring and logging should be enhanced to detect suspicious savevm data patterns, and regular security assessments should be conducted to verify the integrity of virtualization environments. Organizations should also consider implementing network-based intrusion detection systems that can identify and block malicious savevm data traffic.