CVE-2008-1945 in QEMU
Summary
by MITRE
QEMU 0.9.0 does not properly handle changes to removable media, which allows guest OS users to read arbitrary files on the host OS by using the diskformat: parameter in the -usbdevice option to modify the disk-image header to identify a different format, a related issue to CVE-2008-2004.
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Analysis
by VulDB Data Team • 08/18/2019
The vulnerability identified as CVE-2008-1945 affects QEMU version 0.9.0 and represents a critical security flaw in the virtualization platform's handling of removable media changes. This issue stems from insufficient validation mechanisms within the virtual machine monitor's disk image processing capabilities, specifically when managing USB device attachments through the -usbdevice option. The vulnerability operates by exploiting the diskformat: parameter functionality to manipulate disk-image headers, allowing malicious guest operating system users to bypass normal file access controls and read arbitrary files from the host system. This represents a significant privilege escalation vector that undermines the fundamental security boundaries between guest and host environments in virtualized computing infrastructures.
The technical implementation of this vulnerability leverages the diskformat: parameter within the -usbdevice option to manipulate how QEMU interprets disk image headers during USB device attachment scenarios. When a guest OS attempts to access removable media through a USB device connection, the QEMU virtual machine monitor fails to properly validate the format specification provided in the disk image header. This validation failure occurs because the system does not adequately verify that the specified disk format corresponds to the actual file content, allowing an attacker to specify an alternative format that causes QEMU to misinterpret the file structure. The vulnerability is particularly dangerous because it operates at the virtualization layer where guest operating systems should be isolated from host system resources, yet it enables direct file system access to host-level data.
From an operational impact perspective, this vulnerability creates a severe threat to virtualized environments where multiple users or untrusted guest operating systems coexist on the same host system. The ability for guest OS users to read arbitrary files from the host opens the door to information disclosure attacks that can expose sensitive data, system configurations, and potentially credentials stored on the host system. The vulnerability is closely related to CVE-2008-2004, indicating a broader class of issues within QEMU's disk image handling mechanisms that affect the integrity of virtual machine isolation. This flaw particularly impacts enterprise environments that rely on virtualization for multi-tenant hosting or development environments where guest OS users may have limited privileges but could exploit this vulnerability to gain unauthorized access to host resources. The vulnerability also aligns with attack patterns described in the MITRE ATT&CK framework under privilege escalation and credential access tactics, as it allows for unauthorized data access that can lead to further exploitation opportunities.
The security implications extend beyond simple file reading capabilities, as this vulnerability can potentially enable attackers to access host system configuration files, log data, and other sensitive information that may contain authentication credentials or system vulnerabilities. The flaw represents a breakdown in the hypervisor's security model where guest operating systems should be contained within their virtual environments and unable to directly access host resources. Remediation efforts must focus on implementing proper input validation and format verification mechanisms within the QEMU virtualization layer, ensuring that disk image headers are properly validated before any format interpretation occurs. The vulnerability highlights the critical importance of secure input handling in virtualization platforms and underscores the need for comprehensive security testing of hypervisor components. Organizations should immediately update to QEMU versions that address this vulnerability and implement additional monitoring to detect unauthorized USB device attachments or suspicious disk format changes that may indicate exploitation attempts.