CVE-2025-27812

Executive Summary

CVE-2025-27812 is a Time-of-Check Time-of-Use (TOCTOU) local privilege escalation vulnerability in MSI Center versions prior to 2.0.52.0. The flaw allows a low-privileged attacker to exploit a race condition between a security check and the actual use of a resource, potentially leading to arbitrary code execution with elevated privileges. The vulnerability has a CVSS score of 8.1, indicating high severity, but the EPSS score is 0.0%, suggesting no active exploitation in the wild at the time of analysis. No public proof-of-concept or exploit code is available, and the patch status remains unknown.

CVSS Breakdown & Threat Level

• CVSS Score: 8.1 (High)
• Attack Vector: Local (AV:L)
• Attack Complexity: High (AC:H)
• Privileges Required: Low (PR:L)
• User Interaction: None (UI:N)
• Scope: Unchanged (S:U)
• Confidentiality Impact: High (C:H)
• Integrity Impact: High (I:H)
• Availability Impact: High (A:H)

The high CVSS score reflects the potential for complete compromise of confidentiality, integrity, and availability, albeit requiring local access and high attack complexity. The TOCTOU nature of the vulnerability makes it challenging to exploit reliably but dangerous if successful.

Deep Dive & Mechanics

The vulnerability resides in MSI Center, a system management utility for MSI motherboards and laptops. The TOCTOU flaw occurs when the software checks a file or resource's state (e.g., permissions or existence) and then uses that resource without proper locking or atomic operations. An attacker can modify the resource between the check and the use, causing the software to operate on a different resource than intended.

For example, MSI Center may check if a configuration file is writable by the current user and then read it. An attacker could replace the file with a symbolic link to a privileged file (e.g., a system binary) after the check but before the read, leading to privilege escalation.

The vulnerability is classified under CWE-367 (TOCTOU Race Condition) and mapped to MITRE ATT&CK tactic T1055 (Process Injection) as a potential vector for code execution.

Vulnerable vs. Patched Code

No specific code diff is available due to the proprietary nature of MSI Center. However, the patched version (2.0.52.0) likely implements proper file locking, atomic operations, or re-validation of resource state after the check to eliminate the race condition.

Vulnerable Pattern (Conceptual):

if (access(file_path, W_OK) == 0) {
    // Race window: attacker can replace file_path here
    fd = open(file_path, O_RDONLY);
    read(fd, buffer, size);
}

Patched Pattern (Conceptual):

fd = open(file_path, O_RDONLY | O_NOFOLLOW);
if (fd != -1) {
    // Check permissions on the opened file descriptor
    struct stat st;
    fstat(fd, &st);
    if (st.st_uid == getuid() && (st.st_mode & S_IWUSR)) {
        read(fd, buffer, size);
    }
    close(fd);
}

Exploitation & Lab Setup

Red Team

Prerequisites:

• Local access to a system running MSI Center < 2.0.52.0
• Low-privileged user account

Exploitation Steps:

1. Identify a file or resource that MSI Center checks and then uses (e.g., a configuration file in %PROGRAMDATA%\MSI\MSI Center\).
2. Create a monitoring script that detects when MSI Center accesses the file.
3. Use a race condition exploit (e.g., a tight loop) to replace the file with a symbolic link to a privileged file (e.g., C:\Windows\System32\config\SAM) between the check and use.
4. Trigger MSI Center to perform the operation (e.g., by launching a specific feature).
5. If successful, MSI Center will read or write to the privileged file, leading to privilege escalation.

Example Race Condition Script (PowerShell):

while ($true) {
    Remove-Item -Path "C:\ProgramData\MSI\MSI Center\target.txt" -Force
    Start-Sleep -Milliseconds 1
    New-Item -ItemType SymbolicLink -Path "C:\ProgramData\MSI\MSI Center\target.txt" -Target "C:\Windows\System32\config\SAM"
    Start-Sleep -Milliseconds 1
}

Blue Team

Detection:

• Monitor for rapid file creation and deletion in MSI Center directories.
• Detect symbolic link creation to sensitive system files.
• Use Sysmon Event ID 11 (FileCreate) and Event ID 1 (ProcessCreate) to correlate suspicious activity.

Mitigation:

• Apply the latest MSI Center update (2.0.52.0 or later).
• Restrict write access to MSI Center directories to only trusted users.
• Enable Windows Defender Attack Surface Reduction (ASR) rules to block symbolic link creation from untrusted processes.

Indicators of Compromise (IOCs)

• File Paths:
  • C:\ProgramData\MSI\MSI Center\*
  • C:\Program Files (x86)\MSI\MSI Center\*
• Registry Keys:
  • HKLM\SOFTWARE\MSI\MSI Center
• Process Names:
  • MSI_Center.exe
  • MSI_Center_Service.exe
• Network Connections:
  • Outbound connections to *.msi.com (legitimate, but may be abused for C2)
• Event Logs:
  • Windows Security Event ID 4670 (Permissions on an object were changed)
  • Sysmon Event ID 11 (FileCreate) with symbolic link creation

Detection Engineering

YARA Rule

rule CVE_2025_27812_MSI_Center_TOCTOU {
    meta:
        description = "Detects potential TOCTOU exploitation attempts against MSI Center"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-27812"
    strings:
        $s1 = "MSI Center" nocase
        $s2 = "TOCTOU" nocase
        $s3 = "race" nocase
    condition:
        any of them
}

Sigma Rule

title: CVE-2025-27812 MSI Center TOCTOU Exploitation
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects symbolic link creation in MSI Center directories
author: Valters IT
date: 2025-04-10
logsource:
    product: windows
    service: sysmon
detection:
    selection:
        EventID: 11
        TargetFilename|contains: 'C:\ProgramData\MSI\MSI Center\'
        TargetFilename|endswith: '.lnk'
    condition: selection
falsepositives:
    - Legitimate MSI Center updates
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-27812 MSI Center Potential C2"; flow:to_server; content:"MSI Center"; nocase; classtype:trojan-activity; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate: Upgrade MSI Center to version 2.0.52.0 or later.
2. Workaround: If patching is not possible, restrict local access to the system and monitor MSI Center directories for suspicious file operations.
3. Long-term: Implement file integrity monitoring (FIM) on MSI Center directories and enforce least privilege principles for all users.
4. Detection: Deploy the provided YARA, Sigma, and Suricata rules to detect exploitation attempts.

Valters IT
Securing Digital Frontiers