CVE-2024-0068

Executive Summary

CVE-2024-0068 is a local privilege escalation vulnerability affecting HYPR Workforce Access on macOS. The flaw is classified as an Improper Link Resolution Before File Access ('Link Following') vulnerability (CWE-59). A low-privileged attacker can exploit a symbolic link to manipulate files owned by the HYPR process, potentially leading to arbitrary file writes or privilege escalation. The CVSS score is 5.5 (Medium), and the attack vector is local. No public exploit code or proof-of-concept has been released, and the EPSS score is 0.0%, indicating low exploitation activity in the wild. The vendor has released a fix in version 8.7.1.

Supply Chain & Package Security

This vulnerability is not related to an open-source package manager (NPM, PyPI, Go, Ruby). It is a proprietary macOS application (HYPR Workforce Access). Supply chain risk is limited to the integrity of the vendor's update distribution channel.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
• Base Score: 5.5 (Medium)
• Attack Vector (AV): Local (L) – The attacker must have local access to the macOS system.
• Attack Complexity (AC): Low (L) – No special conditions are required.
• Privileges Required (PR): Low (L) – The attacker needs a standard user account.
• User Interaction (UI): None (N) – No user action is required beyond the attacker's own actions.
• Scope (S): Unchanged (U) – The vulnerability does not affect resources beyond the HYPR process.
• Confidentiality (C): None (N) – No data exposure.
• Integrity (I): High (H) – The attacker can modify files, potentially leading to privilege escalation or application compromise.
• Availability (A): None (N) – No denial-of-service impact.

Threat Level: Medium. The local attack vector and low privileges required make it a realistic threat for post-exploitation scenarios or insider threats. However, the lack of public exploits and low EPSS score reduce immediate risk.

Deep Dive & Mechanics

The vulnerability resides in how HYPR Workforce Access handles file operations on macOS. The application creates or accesses files in a directory that is writable by the user (e.g., /tmp or a user-specific directory). A low-privileged attacker can create a symbolic link (symlink) pointing from the expected file path to a sensitive file (e.g., a configuration file owned by root or another user). When the HYPR process follows the symlink, it performs file operations (read/write) on the target file, allowing the attacker to manipulate files they would not normally have access to.

Root Cause: The application does not verify that the file path is a regular file (not a symlink) before performing operations. This is a classic "Time-of-Check Time-of-Use" (TOCTOU) issue, but here it is exploited via a symlink race condition.

Attack Scenario:

1. Attacker gains a low-privileged shell on the macOS system.
2. Attacker identifies a file path that the HYPR process will access (e.g., a log file or temporary file).
3. Attacker removes the legitimate file and creates a symlink pointing to a target file (e.g., /etc/passwd or a HYPR configuration file).
4. When the HYPR process runs (e.g., during authentication or update), it follows the symlink and writes data to the target file.
5. The attacker can overwrite configuration files to escalate privileges or disrupt the service.

Vulnerable vs. Patched Code

No specific code snippets are available from the vendor. However, the fix in version 8.7.1 likely involves:

• Vulnerable: The application uses open() or fopen() without checking if the path is a symlink.
• Patched: The application uses O_NOFOLLOW flag (on macOS) or calls lstat() before open() to detect and reject symlinks.

Conceptual Example (Vulnerable):

// Vulnerable: follows symlinks
int fd = open("/tmp/hypr_temp.log", O_WRONLY | O_CREAT, 0644);
write(fd, data, len);
close(fd);

Conceptual Example (Patched):

// Patched: rejects symlinks
struct stat st;
if (lstat("/tmp/hypr_temp.log", &st) == 0 && S_ISLNK(st.st_mode)) {
    // Reject symlink
    return -1;
}
int fd = open("/tmp/hypr_temp.log", O_WRONLY | O_CREAT | O_NOFOLLOW, 0644);
if (fd == -1) {
    // Handle error
}
write(fd, data, len);
close(fd);

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Local access to a macOS system with HYPR Workforce Access < 8.7.1.
• A low-privileged user account.

Steps:

1. Identify the target file path used by HYPR (e.g., via fs_usage or lsof).
2. Create a symlink:

   # Assume HYPR writes to /tmp/hypr_update.log
   ln -sf /etc/passwd /tmp/hypr_update.log
   

3. Trigger the HYPR process (e.g., by initiating an authentication request or waiting for a scheduled task).
4. The HYPR process will write to /etc/passwd, potentially allowing the attacker to add a new user or modify existing entries.

Note: No public exploit code is available. The above is a conceptual demonstration.

Blue Team (Detection & Hardening)

Detection:

• Monitor for symlink creation in directories writable by low-privileged users (e.g., /tmp, /var/tmp).
• Use endpoint detection and response (EDR) to alert on processes following symlinks to sensitive files.

Hardening:

• Apply the vendor patch (upgrade to 8.7.1).
• Restrict write access to /tmp and other world-writable directories using macOS security policies (e.g., sandbox-exec).
• Use macOS's sanbox or TCC to limit HYPR's file access.

Indicators of Compromise (IOCs)

• File System Artifacts:
  • Unexpected symlinks in /tmp or /var/tmp pointing to system files (e.g., /etc/passwd, /etc/sudoers).
  • Modified system configuration files (e.g., /etc/passwd with new entries).
• Process Behavior:
  • HYPR process (hyprd or similar) accessing files outside its expected scope.
  • Unusual file write operations by the HYPR process to sensitive paths.
• Logs:
  • macOS unified logs showing symlink-related errors or file access denials.
  • Audit logs (if enabled) showing open calls with symlink targets.

Detection Engineering

YARA Rule

rule CVE_2024_0068_Symlink_Exploit {
    meta:
        description = "Detects symlink creation targeting HYPR Workforce Access"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-0068"
    strings:
        $symlink_cmd = "ln -sf" ascii wide nocase
        $hypr_path = "/tmp/hypr" ascii wide nocase
        $target_system = "/etc/passwd" ascii wide nocase
    condition:
        $symlink_cmd and ($hypr_path or $target_system)
}

Sigma Rule

title: CVE-2024-0068 - Symlink Exploitation Against HYPR Workforce Access
id: 8a9b3c2d-1e5f-4a7b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects creation of symlinks in world-writable directories targeting HYPR files
author: Valters IT
date: 2025-04-10
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2024-0068
logsource:
    category: process_creation
    product: macos
detection:
    selection:
        Image|endswith: '/ln'
        CommandLine|contains|all:
            - '-sf'
            - '/tmp/hypr'
    condition: selection
falsepositives:
    - Legitimate administrative scripts
level: high

Suricata Rule

alert file_info any any -> any any (msg:"CVE-2024-0068 - Symlink to HYPR temp file"; file.name:/tmp/hypr.*; file.is_symlink:true; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Upgrade: Update HYPR Workforce Access to version 8.7.1 or later.
2. Workaround: If patching is not possible, restrict write access to /tmp and /var/tmp for non-admin users using macOS's chmod or sandbox profiles.

Long-term Measures:

• Implement file integrity monitoring (FIM) for critical system files.
• Use macOS's Endpoint Security Framework to monitor symlink creation.
• Conduct regular security audits of third-party applications.

Valters IT Signature:

Valters IT
Senior DevSecOps Engineer
Cyber Threat Intelligence Expert