CVE-2019-8840
📋 TL;DR
CVE-2019-8840 is an out-of-bounds read vulnerability in Xcode that could allow arbitrary code execution when compiling untrusted source code. This affects developers using Xcode versions before 11.3 to compile projects from untrusted sources. Successful exploitation could lead to compromise of the developer's system with user privileges.
💻 Affected Systems
- Xcode
📦 What is this software?
Xcode by Apple
⚠️ Risk & Real-World Impact
Worst Case
Attackers could execute arbitrary code on the developer's machine with user privileges, potentially leading to full system compromise through privilege escalation.
Likely Case
Developers who compile untrusted source code (e.g., from open source repositories, third-party libraries) could have their development systems compromised.
If Mitigated
If developers only compile trusted source code and have proper security controls, the risk is minimal.
🎯 Exploit Status
Exploitation requires convincing a developer to compile malicious source code. No public exploit code is known.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Xcode 11.3 and later
Vendor Advisory: https://support.apple.com/en-us/HT210796
Restart Required: No
Instructions:
1. Open App Store on macOS 2. Search for Xcode updates 3. Install Xcode 11.3 or later 4. Verify installation by checking Xcode version
🔧 Temporary Workarounds
Avoid Untrusted Source Compilation
allOnly compile source code from trusted, verified sources. Review all third-party dependencies before compilation.
Use Sandboxed Development Environment
linuxCompile untrusted code in isolated containers or virtual machines to limit potential damage.
docker run --rm -v $(pwd):/src -w /src gcc:latest make
🧯 If You Can't Patch
- Implement strict source code review processes for all compiled code
- Isolate development environments from production systems and sensitive data
🔍 How to Verify
Check if Vulnerable:
Check Xcode version: xcodebuild -version. If version is earlier than 11.3, the system is vulnerable.Check Version:
xcodebuild -versionVerify Fix Applied:
Run xcodebuild -version and confirm version is 11.3 or later.📡 Detection & Monitoring
Log Indicators:
- Unusual compilation processes from untrusted sources
- Xcode crashes during compilation
Network Indicators:
- Downloads of suspicious source code repositories
SIEM Query:
process_name="xcodebuild" AND (source="untrusted_repo" OR parent_process="curl" OR parent_process="wget")