CVE-2024-11467

Executive Summary

CVE-2024-11467 is a Local Privilege Escalation (LPE) vulnerability in Omnissa Horizon Client for macOS. The flaw stems from a logic error in the client’s privilege management, allowing an attacker with standard user access to escalate to root privileges. With a CVSS score of 7.8 (High), this vulnerability poses a significant risk in enterprise environments where Horizon Client is deployed on macOS endpoints. No public proof-of-concept (PoC) or exploit code has been released, and no patch is currently available. The EPSS score is 0.0%, indicating low exploitation likelihood in the wild, but the impact is severe if exploited.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It is a native macOS application (Omnissa Horizon Client) and does not involve package manager supply chain risks.

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 a standard user account.
• User Interaction: None (UI:N) – no user action required beyond initial access.
• Scope: Unchanged (S:U) – the vulnerable component and the impacted component are the same.
• Confidentiality, Integrity, Availability: All High (C:H/I:H/A:H) – full system compromise.

Threat Level: High. While no active exploitation has been observed, the ability to escalate from user to root on macOS endpoints in enterprise environments makes this a critical risk for organizations using Omnissa Horizon Client.

Deep Dive & Mechanics

The vulnerability resides in the Omnissa Horizon Client for macOS, which is used to connect to virtual desktops and applications. The logic flaw likely occurs during privilege separation or when the client performs operations that require elevated permissions (e.g., installing updates, modifying system files, or accessing protected resources). The client may incorrectly handle authorization checks, allowing a non-privileged process to invoke privileged functions.

Technical Details:

• The flaw is categorized under CWE-269 (Improper Privilege Management).
• The attack surface is local; an attacker must have a user account on the macOS system.
• The vulnerability may be triggered via a crafted IPC message, a symlink attack, or by exploiting a race condition in the client’s privilege escalation mechanism.
• Since no patch exists, the exact vulnerable code path is unknown, but typical macOS LPE vectors involve:
  • XPC Services: Misconfigured XPC services that allow arbitrary code execution as root.
  • Authorization Bypass: Flawed use of AuthorizationExecuteWithPrivileges or similar APIs.
  • Dylib Hijacking: Loading malicious dynamic libraries due to insecure @rpath or LC_LOAD_DYLIB entries.

Vulnerable vs. Patched Code

No patch is available, so a direct code comparison cannot be made. However, based on the vulnerability type, the following hypothetical example illustrates the flaw:

Vulnerable Code (Conceptual):

// Vulnerable: No validation of caller's entitlement
- (void)performPrivilegedOperation:(NSDictionary *)params {
    // Directly executes with root privileges without checking caller
    AuthorizationExecuteWithPrivileges(authRef, "/usr/bin/somecommand", kAuthorizationFlagDefaults, args, NULL);
}

Patched Code (Hypothetical):

// Patched: Validate caller's entitlement and audit
- (void)performPrivilegedOperation:(NSDictionary *)params {
    // Check if caller has proper entitlement
    if (![self validateCallerEntitlement]) {
        [self logSecurityEvent:@"Unauthorized privilege escalation attempt"];
        return;
    }
    // Use sandboxed helper tool with limited privileges
    [self.helperTool performOperationWithParams:params];
}

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• macOS system with Omnissa Horizon Client installed (any version).
• A standard user account (non-admin).

Exploitation Steps:

1. Reconnaissance: Identify the Horizon Client process and its XPC services.

   ps aux | grep -i horizon
   ls /Applications/Omnissa\ Horizon\ Client.app/Contents/MacOS/
   

2. Identify Vulnerable Service: Look for XPC services running as root.

   launchctl list | grep -i horizon
   

3. Craft Exploit: Since no public PoC exists, a typical approach would be to:
   • Create a malicious dylib that hooks a function in the Horizon Client.
   • Use DYLD_INSERT_LIBRARIES to inject it.
   • Trigger the privileged operation via IPC.
4. Escalate Privileges: Once the exploit runs, the attacker gains a root shell.

   # Example: After successful exploitation
   id
   uid=0(root) gid=0(wheel)
   

Note: This is a conceptual lab setup. Actual exploitation requires reverse engineering the client binary.

Blue Team (Defensive)

Detection & Prevention:

• Monitor for unusual child processes spawned by Horizon Client (e.g., bash, sh, python).
• Audit XPC service connections using log stream or osquery.
• Restrict user permissions – ensure users do not have unnecessary write access to application directories.
• Enable System Integrity Protection (SIP) – prevents dylib injection in protected paths.
• Use endpoint detection and response (EDR) tools to alert on privilege escalation attempts.

Hunting Query (osquery):

SELECT * FROM processes WHERE parent LIKE '%Horizon%' AND name IN ('bash','sh','python','perl');

Indicators of Compromise (IOCs)

• File Hashes (SHA256): (None available – no known malware samples)
• Process Names: Horizon Client, VMwareHorizonClient (or similar)
• Network Connections: Unusual outbound connections from Horizon Client to non-standard ports.
• File System Changes: Creation of files in /tmp/ or /Library/LaunchDaemons/ by non-root users.
• Log Entries: macOS Unified Log entries showing AuthorizationExecuteWithPrivileges calls from unexpected PIDs.

Example Log Entry (Unified Log):

2024-12-01 10:00:00.000+0000 localhost kernel[0] (Security): AuthorizationExecuteWithPrivileges called by PID 1234 (Horizon Client)

Detection Engineering

YARA Rule

rule CVE_2024_11467_Horizon_LPE {
    meta:
        description = "Detects potential exploitation of CVE-2024-11467 in Omnissa Horizon Client for macOS"
        author = "Valters IT"
        date = "2024-12-01"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2024-11467"
    strings:
        $s1 = "AuthorizationExecuteWithPrivileges" ascii wide nocase
        $s2 = "Horizon Client" ascii wide nocase
        $s3 = "performPrivilegedOperation" ascii wide nocase
    condition:
        all of them
}

Sigma Rule

title: CVE-2024-11467 - Omnissa Horizon Client LPE Attempt
id: 8a3f7c2e-5d1b-4a9f-8c6e-2b1d3f4a5c6d
status: experimental
description: Detects potential exploitation of CVE-2024-11467 via suspicious child processes spawned by Horizon Client
author: Valters IT
date: 2024-12-01
logsource:
    category: process_creation
    product: macos
detection:
    selection:
        ParentImage|endswith: '/Horizon Client'
        Image|endswith:
            - '/bash'
            - '/sh'
            - '/python'
            - '/perl'
    condition: selection
falsepositives:
    - Legitimate administrative scripts run by admin users
level: high

Suricata Rule

alert ip any any -> any any (msg:"CVE-2024-11467 - Omnissa Horizon Client LPE Attempt"; flow:to_server; content:"AuthorizationExecuteWithPrivileges"; nocase; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Restrict user accounts – limit standard users from installing or modifying applications.
2. Monitor for suspicious activity using the provided detection rules.
3. Apply principle of least privilege – ensure Horizon Client runs with minimal necessary permissions.

Long-term Fix:

• Await an official patch from Omnissa. Monitor their security advisory page.
• If possible, disable the vulnerable feature or use application whitelisting to block unauthorized execution.

Workaround:

• Use macOS Parental Controls or MDM policies to prevent non-admin users from running Horizon Client.
• Consider using a virtualized environment or containerized Horizon Client to isolate the vulnerability.

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Expert