CVE-2018-12392
📋 TL;DR
This vulnerability allows attackers to trigger a potentially exploitable crash in Firefox, Firefox ESR, and Thunderbird by manipulating user events in nested loops while opening documents through script. It affects all users running vulnerable versions of these applications, potentially leading to remote code execution.
💻 Affected Systems
- Mozilla Firefox
- Mozilla Firefox ESR
- Mozilla Thunderbird
📦 What is this software?
Firefox by Mozilla
Firefox by Mozilla
Thunderbird by Mozilla
Ubuntu Linux by Canonical
Ubuntu Linux by Canonical
Ubuntu Linux by Canonical
Ubuntu Linux by Canonical
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, data theft, or malware installation.
Likely Case
Application crash leading to denial of service or potential remote code execution in targeted attacks.
If Mitigated
Limited impact with proper patching and security controls in place.
🎯 Exploit Status
Exploitation requires user interaction (opening a malicious document), but no authentication is needed. The high CVSS score suggests significant impact potential.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Firefox 63, Firefox ESR 60.3, Thunderbird 60.3
Vendor Advisory: https://www.mozilla.org/en-US/security/advisories/mfsa2018-26/
Restart Required: Yes
Instructions:
1. Open the affected application (Firefox/Thunderbird). 2. Go to Help > About Firefox/Thunderbird. 3. Allow the application to check for and install updates. 4. Restart the application when prompted.
🔧 Temporary Workarounds
Disable JavaScript
allTemporarily disable JavaScript to prevent exploitation through malicious scripts.
In Firefox: about:config > javascript.enabled = false
Use alternative browser
allSwitch to an unaffected browser until patches can be applied.
🧯 If You Can't Patch
- Restrict user access to untrusted websites and documents
- Implement application whitelisting to prevent execution of vulnerable browser versions
🔍 How to Verify
Check if Vulnerable:
Check the application version in Help > About Firefox/Thunderbird and compare with affected versions.Check Version:
On Linux: firefox --version | head -1; On Windows: Check Help > About FirefoxVerify Fix Applied:
Verify the application version is Firefox ≥63, Firefox ESR ≥60.3, or Thunderbird ≥60.3.📡 Detection & Monitoring
Log Indicators:
- Application crash logs with memory access violations
- Unexpected browser/email client termination events
Network Indicators:
- Unusual outbound connections following browser crashes
- Downloads of suspicious documents preceding crashes
SIEM Query:
source="*firefox*" OR source="*thunderbird*" AND (event_type="crash" OR severity="critical")🔗 References
- http://www.securityfocus.com/bid/105718
- http://www.securityfocus.com/bid/105769
- http://www.securitytracker.com/id/1041944
- https://access.redhat.com/errata/RHSA-2018:3005
- https://access.redhat.com/errata/RHSA-2018:3006
- https://access.redhat.com/errata/RHSA-2018:3531
- https://access.redhat.com/errata/RHSA-2018:3532
- https://bugzilla.mozilla.org/show_bug.cgi?id=1492823
- https://lists.debian.org/debian-lts-announce/2018/11/msg00008.html
- https://lists.debian.org/debian-lts-announce/2018/11/msg00011.html
- https://security.gentoo.org/glsa/201811-04
- https://security.gentoo.org/glsa/201811-13
- https://usn.ubuntu.com/3801-1/
- https://usn.ubuntu.com/3868-1/
- https://www.debian.org/security/2018/dsa-4324
- https://www.debian.org/security/2018/dsa-4337
- https://www.mozilla.org/security/advisories/mfsa2018-26/
- https://www.mozilla.org/security/advisories/mfsa2018-27/
- https://www.mozilla.org/security/advisories/mfsa2018-28/
- http://www.securityfocus.com/bid/105718
- http://www.securityfocus.com/bid/105769
- http://www.securitytracker.com/id/1041944
- https://access.redhat.com/errata/RHSA-2018:3005
- https://access.redhat.com/errata/RHSA-2018:3006
- https://access.redhat.com/errata/RHSA-2018:3531
- https://access.redhat.com/errata/RHSA-2018:3532
- https://bugzilla.mozilla.org/show_bug.cgi?id=1492823
- https://lists.debian.org/debian-lts-announce/2018/11/msg00008.html
- https://lists.debian.org/debian-lts-announce/2018/11/msg00011.html
- https://security.gentoo.org/glsa/201811-04
- https://security.gentoo.org/glsa/201811-13
- https://usn.ubuntu.com/3801-1/
- https://usn.ubuntu.com/3868-1/
- https://www.debian.org/security/2018/dsa-4324
- https://www.debian.org/security/2018/dsa-4337
- https://www.mozilla.org/security/advisories/mfsa2018-26/
- https://www.mozilla.org/security/advisories/mfsa2018-27/
- https://www.mozilla.org/security/advisories/mfsa2018-28/
