CVE-2025-14303 Overview
CVE-2025-14303 affects certain MSI motherboard models that fail to properly enable the Input-Output Memory Management Unit (IOMMU) during the pre-boot phase. An unauthenticated attacker with physical access can connect a Direct Memory Access (DMA) capable PCIe device and read or write arbitrary physical memory. The attack occurs before the operating system kernel and its security features are loaded, bypassing OS-level protections entirely. The vulnerability is classified under [CWE-693] Protection Mechanism Failure and requires physical access to the target system.
Critical Impact
A DMA-capable PCIe device connected to an affected MSI motherboard can read and write arbitrary physical memory before the OS boots, enabling credential theft, disk encryption key extraction, and pre-boot code injection.
Affected Products
- MSI motherboards (specific models identified in vendor advisory)
- Systems booting on affected MSI firmware without IOMMU enforcement
- Endpoints exposing external PCIe interfaces such as Thunderbolt or ExpressCard
Discovery Timeline
- 2025-12-17 - CVE-2025-14303 published to the National Vulnerability Database (NVD)
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-14303
Vulnerability Analysis
The flaw resides in how affected MSI motherboard firmware initializes the platform's DMA remapping hardware. IOMMU (Intel VT-d or AMD-Vi) translates and restricts DMA transactions from PCIe devices to specific memory regions. When IOMMU is not enabled or not locked in the pre-boot environment, any bus-mastering PCIe device can issue DMA read and write operations directly against system RAM. Because this occurs before the OS kernel loads, host-based defenses such as Kernel DMA Protection cannot intervene. The condition maps to [CWE-693] because a security control that was expected to be present is absent or misconfigured.
Root Cause
The firmware does not activate the DMA remapping engine before enumerating PCIe devices or exposing hot-plug capable ports. The Advanced Configuration and Power Interface (ACPI) DMAR/IVRS tables that inform the OS of IOMMU state may also be inconsistent. As a result, the trust boundary that isolates peripheral devices from host memory is never established during boot.
Attack Vector
An attacker with brief physical access connects a DMA-capable device to an external PCIe interface, such as Thunderbolt, M.2, ExpressCard, or an internal PCIe slot. Tools such as PCILeech interact with the FPGA-based DMA device to scan memory for LSASS credential structures, BitLocker Volume Master Keys, or kernel structures. The attacker can then patch memory to disable authentication, inject a bootkit, or exfiltrate sensitive data. No user interaction or valid credentials are required.
See the MSI Product Security Advisories and the TWCERT Cybersecurity Report for model-specific technical details.
Detection Methods for CVE-2025-14303
Indicators of Compromise
- Unrecognized PCIe devices enumerated in Windows Event Log source Microsoft-Windows-Kernel-PnP shortly after boot or resume
- Unexpected Thunderbolt or ExpressCard device connections logged in HKLM\SYSTEM\CurrentControlSet\Enum\PCI
- BitLocker recovery events or unexpected credential access patterns following physical access to the host
Detection Strategies
- Audit firmware settings across the fleet to confirm VT-d or AMD-Vi is enabled and locked in BIOS/UEFI
- Query Windows systems for DmaGuardPolicy and AllowedBuses under HKLM\SYSTEM\CurrentControlSet\Control\DmaSecurity to verify Kernel DMA Protection status
- Cross-reference msinfo32 output for Virtualization-based security and Kernel DMA Protection: On to identify non-compliant hosts
Monitoring Recommendations
- Alert on PCIe device insertions on systems in secure areas, especially outside of maintenance windows
- Monitor for unauthorized firmware configuration changes using vendor management tooling
- Correlate physical access badge logs with boot events on high-value endpoints
How to Mitigate CVE-2025-14303
Immediate Actions Required
- Apply the firmware update published on the MSI Product Security Advisories page for each affected motherboard model
- Enable VT-d (Intel) or IOMMU/AMD-Vi (AMD) in BIOS/UEFI and set an administrator password to prevent modification
- Enable Kernel DMA Protection on Windows 10/11 systems and verify status through msinfo32
Patch Information
MSI has published firmware updates through its Product Security Advisories portal. Administrators should identify the affected motherboard model, download the corresponding BIOS release, and follow the vendor's flashing procedure. Consult the TWCERT Cybersecurity Press Release for the coordinated disclosure summary.
Workarounds
- Disable unused external PCIe interfaces such as Thunderbolt in BIOS/UEFI where the workflow permits
- Enforce full-disk encryption with pre-boot authentication so memory does not contain unlockable keys at rest
- Restrict physical access to endpoints storing sensitive data and enable chassis intrusion alerts where supported
- Configure Windows Group Policy to block new DMA devices when the system is locked
# Verify Kernel DMA Protection status on Windows
powershell -Command "(Get-CimInstance -ClassName Win32_DeviceGuard -Namespace root\Microsoft\Windows\DeviceGuard).VirtualizationBasedSecurityStatus"
# Check IOMMU/VT-d status on Linux
dmesg | grep -e DMAR -e IOMMU
# Group Policy path to block new DMA devices when locked
# Computer Configuration > Administrative Templates > System > Kernel DMA Protection
# Setting: "Enumeration policy for external devices incompatible with Kernel DMA Protection" = Block All
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
