CVE-2017-13908
📋 TL;DR
This vulnerability allows a local attacker to execute non-executable text files via an SMB share on macOS systems. The issue involves improper file permission handling that could lead to arbitrary code execution. Affected systems include macOS High Sierra, Sierra, and El Capitan before specific security updates.
💻 Affected Systems
- macOS
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Local privilege escalation leading to full system compromise and persistent backdoor installation.
Likely Case
Local attacker gains unauthorized code execution with user-level privileges on vulnerable systems.
If Mitigated
No impact if systems are fully patched or SMB sharing is disabled.
🎯 Exploit Status
Requires local network access and ability to interact with SMB shares. No public exploit code available.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: macOS High Sierra 10.13.1, Security Update 2017-001 Sierra, Security Update 2017-004 El Capitan
Vendor Advisory: https://support.apple.com/en-us/HT208144
Restart Required: Yes
Instructions:
1. Open System Preferences > Software Update. 2. Install available security updates. 3. Restart the system when prompted.
🔧 Temporary Workarounds
Disable SMB Sharing
macOSDisable SMB file sharing to prevent exploitation via network attack vector.
sudo launchctl unload -w /System/Library/LaunchDaemons/com.apple.smbd.plist
Restrict SMB Access
macOSConfigure firewall to restrict SMB access to trusted networks only.
sudo /usr/libexec/ApplicationFirewall/socketfilterfw --setblockall on
sudo /usr/libexec/ApplicationFirewall/socketfilterfw --add /usr/sbin/smbd
🧯 If You Can't Patch
- Disable SMB file sharing completely on affected systems
- Implement network segmentation to isolate vulnerable systems from untrusted networks
🔍 How to Verify
Check if Vulnerable:
Check macOS version: if running High Sierra 10.13, Sierra, or El Capitan without security updates, system is vulnerable.Check Version:
sw_versVerify Fix Applied:
Verify macOS version is 10.13.1 or later for High Sierra, or confirm Security Update 2017-001/004 is installed.📡 Detection & Monitoring
Log Indicators:
- Unusual SMB connection attempts
- Failed authentication attempts on SMB shares
- Execution of unexpected text files via SMB
Network Indicators:
- Unusual SMB traffic patterns
- SMB connections from unexpected sources
- File transfers followed by execution attempts
SIEM Query:
source="*smbd*" AND (event="authentication_failure" OR event="file_execution")