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CVE-2019-8539

7.8 HIGH

📋 TL;DR

CVE-2019-8539 is a memory initialization vulnerability in macOS that allows a malicious application to execute arbitrary code with system privileges. This affects macOS Sierra, High Sierra, and Mojave systems. Successful exploitation gives attackers complete control over the affected system.

💻 Affected Systems

Products:
  • macOS
Versions: macOS Sierra, High Sierra, and Mojave prior to security updates
Operating Systems: macOS
Default Config Vulnerable: ⚠️ Yes
Notes: All default configurations of affected macOS versions are vulnerable. No special configuration required for exploitation.

📦 What is this software?

Mac Os X by Apple

View all CVEs affecting Mac Os X →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Full system compromise with root-level access, allowing installation of persistent malware, data theft, and lateral movement across the network.

🟠

Likely Case

Local privilege escalation where a user with standard privileges runs a malicious application that gains system-level access to the device.

🟢

If Mitigated

Limited impact if systems are fully patched, applications are from trusted sources only, and proper endpoint protection is in place.

🌐 Internet-Facing: LOW - This requires local application execution, not directly exploitable over the network.
🏢 Internal Only: MEDIUM - Risk exists from malicious applications executed by users on vulnerable macOS systems within the organization.

🎯 Exploit Status

Public PoC: ✅ No
Weaponized: UNKNOWN
Unauthenticated Exploit: ✅ No
Complexity: MEDIUM

Exploitation requires user interaction to execute a malicious application. No public exploit code was widely available at disclosure.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: macOS Mojave 10.14.6, Security Update 2019-004 High Sierra, Security Update 2019-004 Sierra

Vendor Advisory: https://support.apple.com/en-us/HT210348

Restart Required: Yes

Instructions:

1. Open System Preferences > Software Update. 2. Install available security updates. 3. Restart the system when prompted.

🔧 Temporary Workarounds

Application Whitelisting

all

Restrict application execution to only approved, signed applications from trusted sources

🧯 If You Can't Patch

  • Implement strict application control policies to prevent execution of untrusted applications
  • Isolate vulnerable systems from critical network segments and monitor for suspicious activity

🔍 How to Verify

Check if Vulnerable:

Check macOS version: If running Sierra, High Sierra, or Mojave without the 2019-004 security updates, the system is vulnerable.

Check Version:

sw_vers

Verify Fix Applied:

Verify macOS version is at least: Mojave 10.14.6, High Sierra with Security Update 2019-004, or Sierra with Security Update 2019-004

📡 Detection & Monitoring

Log Indicators:

  • Unexpected privilege escalation events in system logs
  • Processes running with unexpected root privileges

Network Indicators:

  • Unusual outbound connections from macOS systems following local application execution

SIEM Query:

source="macos_system_logs" AND (event="privilege_escalation" OR process="root")

📊 Metadata

CVE ID: CVE-2019-8539
CVSS v3 Score: 7.8 (HIGH)
CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Published: October 27, 2020
Last Updated: November 21, 2024

🔗 References

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