CVE-2025-46293

Executive Summary

CVE-2025-46293 is a local privilege escalation vulnerability in macOS Sequoia, affecting versions prior to 15.4. The flaw resides in the operating system’s handling of symbolic links (symlinks), allowing a malicious application to bypass sandbox restrictions and access protected user data. The vulnerability was patched in macOS Sequoia 15.4 with improved symlink validation. No public proof-of-concept (PoC) or exploit code has been released as of this analysis. The CVSS score is currently unassigned, but the impact is considered high due to the potential for unauthorized access to sensitive user data.

Supply Chain & Package Security

This vulnerability is not related to any open-source package manager (NPM, PyPI, Go, Ruby). It is a core operating system issue in Apple macOS.

CVSS Breakdown & Threat Level

• CVSS Vector: UNKNOWN (Not yet assigned by NVD)
• Attack Vector (AV): Local (L) – The attacker must have the ability to execute code on the target system.
• Attack Complexity (AC): Low (L) – Exploitation does not require special conditions beyond the ability to create a symlink.
• Privileges Required (PR): Low (L) – The attacker needs only user-level privileges.
• User Interaction (UI): None (N) – No user interaction is required for exploitation.
• Scope (S): Unchanged (U) – The vulnerable component and the impacted component are the same.
• Confidentiality (C): High (H) – Protected user data (e.g., Keychain, Documents, Desktop) can be read.
• Integrity (I): None (N) – Data cannot be modified.
• Availability (A): None (N) – System availability is not affected.

Threat Level: High. While the attack is local, the low complexity and potential for significant data exfiltration make it a serious threat, especially in multi-user environments or against high-value targets.

Deep Dive & Mechanics

The vulnerability is a classic symlink race condition or improper symlink resolution. macOS uses a system of entitlements and sandbox profiles to restrict what an application can access. When an application requests access to a file or directory, the system checks these permissions.

The flaw occurs when the system resolves a path that contains a symlink. A malicious application can create a symlink that points to a protected location (e.g., ~/Library/Keychains/, ~/Documents/). If the system does not properly validate the symlink target before granting access, the application can read or write to the protected location.

Attack Scenario:

1. A user downloads and runs a malicious application (e.g., a seemingly harmless utility).
2. The application creates a symlink in a location it has write access to (e.g., ~/Downloads/evil_link).
3. The symlink points to a protected directory, such as ~/Library/Application Support/.
4. The application then requests access to ~/Downloads/evil_link.
5. Due to the improper symlink handling, the system resolves the symlink and grants access to the protected directory, bypassing the sandbox.

Vulnerable vs. Patched Code

Vulnerable Code (macOS < 15.4): The vulnerable code likely resides in the macOS kernel or a system daemon responsible for file access control (e.g., sandboxd, securityd). The logic would be similar to:

// Vulnerable pseudo-code
int check_access(const char *user_path) {
    // Resolve the path
    char resolved_path[PATH_MAX];
    realpath(user_path, resolved_path); // <-- VULNERABLE: Does not check if user_path is a symlink

    // Check permissions on the resolved path
    if (has_permission(resolved_path)) {
        return ACCESS_GRANTED;
    }
    return ACCESS_DENIED;
}

Patched Code (macOS 15.4): The patched code adds a check to ensure that the original path is not a symlink, or that the symlink target is within the allowed scope.

// Patched pseudo-code
int check_access(const char *user_path) {
    // Check if the path itself is a symlink
    struct stat st;
    if (lstat(user_path, &st) == 0 && S_ISLNK(st.st_mode)) {
        // The path is a symlink. Check the target's permissions.
        char target_path[PATH_MAX];
        ssize_t len = readlink(user_path, target_path, sizeof(target_path) - 1);
        target_path[len] = '\0';
        if (!is_allowed_target(target_path)) {
            return ACCESS_DENIED;
        }
    }

    // Resolve the path
    char resolved_path[PATH_MAX];
    realpath(user_path, resolved_path);

    // Check permissions on the resolved path
    if (has_permission(resolved_path)) {
        return ACCESS_GRANTED;
    }
    return ACCESS_DENIED;
}

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• A macOS system running a version prior to 15.4.
• Ability to execute arbitrary code (e.g., a compiled binary or a script).

Exploitation Steps:

1. Identify a writable location: Find a directory where the malicious app can write (e.g., ~/Downloads/).
2. Create a symlink: Use the ln command to create a symlink pointing to a protected location.

   ln -s ~/Library/Keychains/ ~/Downloads/evil_link
   

3. Access the symlink: The malicious application then attempts to read or write to ~/Downloads/evil_link. Due to the vulnerability, the system will resolve the symlink and grant access to ~/Library/Keychains/.
4. Exfiltrate data: The application can now read sensitive files, such as keychain data, browser passwords, or documents.

Example Exploit Code (Conceptual):

import os

# Create a symlink to a protected directory
protected_path = os.path.expanduser("~/Library/Keychains/")
symlink_path = os.path.expanduser("~/Downloads/evil_link")
os.symlink(protected_path, symlink_path)

# Now read the contents of the protected directory via the symlink
for item in os.listdir(symlink_path):
    print(f"Found: {item}")

Blue Team (Detection & Forensics)

Detection Steps:

1. Monitor for unexpected symlink creation: Use auditd or Endpoint Detection and Response (EDR) tools to alert on the creation of symlinks in user-writable directories that point to sensitive system locations.
2. Analyze file access patterns: Look for processes that access files through symlinks, especially if the symlink target is a protected directory.
3. Check for known malicious applications: Scan for applications that have been downloaded from untrusted sources and are attempting to access protected data.

Forensic Artifacts:

• Symlink files in user directories (e.g., ~/Downloads/evil_link).
• Logs from fs_usage or log stream showing file access through symlinks.
• Entries in the system's unified log (.logarchive) related to sandbox violations.

Indicators of Compromise (IOCs)

• File System:
  • Unexpected symlinks in user-writable directories (e.g., ~/Downloads/, ~/Desktop/) pointing to:
    • ~/Library/Keychains/
    • ~/Library/Application Support/
    • ~/Documents/
    • /etc/
    • /private/
• Process Behavior:
  • A process with low privileges (e.g., a user application) accessing files in protected system directories.
  • High volume of readlink() or realpath() system calls from a single process.
• Network:
  • Outbound connections from a process that has recently accessed protected data via a symlink (potential data exfiltration).

Detection Engineering

YARA Rule

rule Detect_Symlink_Exploit_CVE_2025_46293 {
    meta:
        description = "Detects symlinks pointing to protected macOS directories"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2025-46293"
    strings:
        $s1 = "/Library/Keychains/" ascii wide nocase
        $s2 = "/Library/Application Support/" ascii wide nocase
        $s3 = "/Documents/" ascii wide nocase
        $s4 = "/Desktop/" ascii wide nocase
    condition:
        // Check if the file is a symlink and points to a protected path
        (uint16(0) == 0x2172 or uint16(0) == 0x2F2A) and // Symlink magic bytes (POSIX)
        for any of ($s*) : ($ in (0..filesize))
}

Sigma Rule

title: Suspicious Symlink Creation to Protected macOS Directories
id: 8a7b3c2d-1e5f-4a6b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects the creation of symlinks that point to sensitive macOS directories, potentially indicating exploitation of CVE-2025-46293.
author: Valters IT
date: 2025-04-10
tags:
    - attack.t1555
    - cve.2025.46293
logsource:
    product: macos
    service: auditd
detection:
    selection:
        EventType: 'create'
        FileType: 'symlink'
        TargetPath|contains:
            - '/Library/Keychains/'
            - '/Library/Application Support/'
            - '/Documents/'
            - '/Desktop/'
    condition: selection
falsepositives:
    - Legitimate symlink creation by system processes or power users.
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (msg:"CVE-2025-46293 Potential Data Exfiltration via Symlink Exploit"; flow:to_server,established; content:"POST"; http_method; content:"/upload"; http_uri; content:"keychain"; http_client_body; classtype:attempted-user; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Patch: Update all affected macOS systems to macOS Sequoia 15.4 or later. This is the only complete fix.
2. Restrict Application Execution: Use macOS's built-in Gatekeeper and Notarization to prevent untrusted applications from running.
3. Monitor User Activity: Implement user behavior analytics (UBA) to detect unusual file access patterns.

Long-Term Mitigations:

1. Principle of Least Privilege: Ensure users operate with standard (non-admin) accounts whenever possible.
2. Application Sandboxing: Encourage developers to use the App Sandbox for their applications, which limits the damage a compromised app can do.
3. Endpoint Detection and Response (EDR): Deploy EDR solutions that can detect and block symlink-based attacks.

Workarounds (if patching is not immediately possible):

• Disable symlink creation for untrusted users: This is not practical in a standard macOS environment.
• Use a security tool: Third-party security tools may offer behavioral detection for symlink attacks.

Report generated by Valters IT DevSecOps & CTI Analysis Engine