CVE-2014-0148 in QEMU
Summary
by MITRE • 09/29/2022
Qemu before 2.0 block driver for Hyper-V VHDX Images is vulnerable to infinite loops and other potential issues when calculating BAT entries, due to missing bounds checks for block_size and logical_sector_size variables. These are used to derive other fields like 'sectors_per_block' etc. A user able to alter the Qemu disk image could ise this flaw to crash the Qemu instance resulting in DoS.
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Analysis
by VulDB Data Team • 09/29/2022
The vulnerability identified as CVE-2014-0148 resides within the QEMU virtualization platform's block driver implementation specifically for Hyper-V Virtual Hard Disk (VHDX) image formats. This flaw represents a critical security issue that affects QEMU versions prior to 2.0, where the software fails to properly validate input parameters during the processing of VHDX disk images. The vulnerability stems from inadequate bounds checking mechanisms that should validate the block_size and logical_sector_size variables before they are used to compute derived fields such as sectors_per_block. These variables serve as fundamental parameters that determine how the virtual disk's internal structure is interpreted and managed by the block driver.
The technical implementation of this vulnerability allows for a class of denial of service attacks through carefully crafted malicious disk images. When QEMU processes a VHDX image with malformed block_size or logical_sector_size values, the absence of proper validation leads to calculations that can result in infinite loops or other computational anomalies. The missing bounds checks create a scenario where an attacker with the ability to modify or inject disk image content can manipulate these critical parameters to cause the QEMU process to enter an infinite loop or consume excessive computational resources. This occurs because the derived values like sectors_per_block become invalid or extremely large, causing the block driver to attempt operations that never complete or consume all available system resources.
The operational impact of CVE-2014-0148 extends beyond simple denial of service conditions to potentially compromise entire virtualization environments. When a QEMU instance crashes due to this vulnerability, it affects the virtual machine hosting that instance, potentially causing guest operating systems to become unavailable or crash. This vulnerability is particularly dangerous in cloud computing environments or virtualization platforms where multiple virtual machines share the same hypervisor resources, as a single malicious disk image could affect the stability of the entire virtualization infrastructure. The vulnerability aligns with CWE-129, which addresses improper validation of array indices, and can be categorized under ATT&CK technique T1499.200, specifically targeting virtualization software to achieve denial of service conditions.
Mitigation strategies for CVE-2014-0148 require immediate patching of affected QEMU installations to version 2.0 or later, where proper bounds checking mechanisms have been implemented. System administrators should also implement strict image validation policies that prevent untrusted users from uploading or modifying disk images within virtualization environments. Network segmentation and access controls should be enforced to limit who can modify virtual disk content, and monitoring systems should be deployed to detect unusual resource consumption patterns that might indicate exploitation attempts. Additionally, virtualization platforms should implement automated image scanning mechanisms to identify potentially malicious disk images before they are mounted by QEMU instances, providing defense in depth against this class of vulnerability that affects the core block driver functionality of the virtualization platform.