CVE-2024-29943
📋 TL;DR
This vulnerability allows an attacker to perform out-of-bounds memory reads or writes on JavaScript objects by exploiting a flaw in Firefox's range-based bounds check elimination. This affects all Firefox users running versions below 124.0.1, potentially leading to arbitrary code execution.
💻 Affected Systems
- Mozilla Firefox
📦 What is this software?
Firefox by Mozilla
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution with the same privileges as the Firefox process, potentially leading to full system compromise.
Likely Case
Browser crash (denial of service) or limited information disclosure through memory reads.
If Mitigated
No impact if Firefox is fully patched or if exploit attempts are blocked by security controls.
🎯 Exploit Status
Exploitation requires JavaScript execution but no authentication. The vulnerability is in the JavaScript engine, making reliable exploitation possible.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 124.0.1
Vendor Advisory: https://www.mozilla.org/security/advisories/mfsa2024-15/
Restart Required: Yes
Instructions:
1. Open Firefox. 2. Click menu → Help → About Firefox. 3. Firefox will check for updates and install version 124.0.1. 4. Restart Firefox when prompted.
🔧 Temporary Workarounds
Disable JavaScript
allTemporarily disable JavaScript execution in Firefox to prevent exploitation.
about:config → javascript.enabled = false
Use Alternative Browser
allSwitch to a different, updated browser until Firefox is patched.
🧯 If You Can't Patch
- Restrict Firefox to only trusted websites using browser policies or extensions.
- Implement network filtering to block known malicious domains and JavaScript sources.
🔍 How to Verify
Check if Vulnerable:
Check Firefox version: about:support → Application Basics → Version. If version is less than 124.0.1, system is vulnerable.Check Version:
firefox --version | grep -o '[0-9]\+\.[0-9]\+\.[0-9]\+'Verify Fix Applied:
Confirm Firefox version is 124.0.1 or higher in about:support.📡 Detection & Monitoring
Log Indicators:
- Firefox crash reports with memory access violation errors
- Unexpected JavaScript execution patterns
Network Indicators:
- Requests to known exploit domains
- Unusual JavaScript payloads in web traffic
SIEM Query:
source="firefox.logs" AND (event="crash" OR event="memory_violation")🔗 References
- http://www.openwall.com/lists/oss-security/2024/03/23/1
- https://bugzilla.mozilla.org/show_bug.cgi?id=1886849
- https://www.mozilla.org/security/advisories/mfsa2024-15/
- http://www.openwall.com/lists/oss-security/2024/03/23/1
- https://bugzilla.mozilla.org/show_bug.cgi?id=1886849
- https://www.mozilla.org/security/advisories/mfsa2024-15/
