CVE-2008-2004 in QEMU
Summary
by MITRE
The drive_init function in QEMU 0.9.1 determines the format of a raw disk image based on the header, which allows local guest users to read arbitrary files on the host by modifying the header to identify a different format, which is used when the guest is restarted.
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Analysis
by VulDB Data Team • 08/10/2019
The vulnerability described in CVE-2008-2004 resides within the QEMU virtualization platform version 0.9.1 where the drive_init function fails to properly validate disk image headers during initialization. This flaw creates a critical security weakness that allows local guest users to exploit the system by manipulating the header of a raw disk image file. The vulnerability specifically targets the format detection mechanism that QEMU employs when determining how to interpret disk image data, enabling attackers to bypass normal file access controls and potentially read arbitrary files from the host system.
The technical implementation of this vulnerability stems from insufficient input validation within the drive_init function which relies on header information to determine disk image format. When a guest operating system modifies the header of a raw disk image to mimic another format type, QEMU accepts this modified header without proper verification. This allows the system to treat the modified image as a different format, causing the virtual machine to attempt to read and process the underlying host filesystem data through the modified image structure. The vulnerability is particularly dangerous because it operates at the virtualization layer where guest users should be isolated from host resources, yet the flawed format detection logic creates an unexpected pathway for information disclosure.
The operational impact of this vulnerability extends beyond simple information disclosure to represent a significant privilege escalation vector within virtualized environments. Local guest users who can modify disk image headers gain unauthorized access to host filesystem contents, potentially exposing sensitive data, configuration files, or system resources. This weakness undermines the fundamental security isolation that virtualization platforms are designed to provide, allowing attackers to perform reconnaissance and data exfiltration attacks without requiring elevated privileges on the host system. The vulnerability is particularly concerning in multi-tenant environments where multiple users share the same hypervisor infrastructure, as it could enable one user to access another user's data or system information.
The root cause of this vulnerability aligns with CWE-20, "Improper Input Validation," where the system fails to properly validate user-provided data before processing it. This flaw also relates to CWE-502, "Deserialization of Untrusted Data," as the system accepts potentially malicious header information without adequate sanitization. From an ATT&CK framework perspective, this vulnerability maps to T1059.001 "Command and Scripting Interpreter: PowerShell" and T1566.001 "Phishing: Spearphishing Attachment" as attackers could potentially leverage this weakness to escalate privileges or gain unauthorized access to host resources. The vulnerability also connects to T1078 "Valid Accounts" and T1005 "Data from Local System" as it allows unauthorized access to system data through legitimate system interfaces.
Mitigation strategies for this vulnerability should include immediate patching of QEMU to version 0.9.2 or later where the format detection logic has been corrected to properly validate disk image headers. System administrators should implement strict access controls on virtual disk images and ensure that guest users cannot modify disk image files. Additional protective measures include monitoring for unusual header modifications, implementing network segmentation to limit guest access to host resources, and deploying host-based intrusion detection systems to identify potential exploitation attempts. The virtualization platform should also enforce proper file permission controls and implement mandatory access controls to prevent unauthorized header modifications that could lead to privilege escalation. Organizations should conduct regular security assessments of their virtualization environments to identify similar validation weaknesses and ensure that all virtualization components are kept up to date with security patches.