Rule Category

BROWSER-FIREFOX -- Snort has detected traffic known to exploit vulnerabilities present in the Firefox browser, or products that have the "Gecko" engine (Thunderbird email client, etc.).

Alert Message

BROWSER-FIREFOX Mozilla Firefox Custom Elements write-after-free attempt

Rule Explanation

A bug exists in Mozilla Firefox Custom Elements where a malicious JavaScript file can cause a write-after-free in the browser. Impact: Attempted User Privilege Gain Details: Ease of Attack:

What To Look For

No information provided

Known Usage

No public information

False Positives

No known false positives

Contributors

Cisco Talos Intelligence Group

Rule Groups

No rule groups

CVE

Rule Vulnerability

CVE Additional Information

CVE-2018-18500
A use-after-free vulnerability can occur while parsing an HTML5 stream in concert with custom HTML elements. This results in the stream parser object being freed while still in use, leading to a potentially exploitable crash. This vulnerability affects Thunderbird < 60.5, Firefox ESR < 60.5, and Firefox < 65.
Details
Severity Base Score9.8
Impact Score5.9 Exploit Score3.9
Confidentiality ImpactHIGH Integrity ImpactHIGH
Availability ImpactHIGH Attack VectorNETWORK
ScopeUNCHANGED User InteractionNONE
Authentication Ease of AccessLOW
Privileges RequiredNONE