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 ReadableStreamCloseInternal out-of-bounds access attempt

Rule Explanation

This rule looks for a certain sequence of JavaScript operations that are designed to cause a state inconsistency bug to manifest, leading to an out-of-bounds read. This bug could be exploited to corrupt memory, potentially leading to arbitrary remote code execution.

What To Look For

This rule alerts when a specifically formatted web page designed to exploit CVE-2020-6806 is detected. CVE-2020-6806 is a memory corruption bug in Mozilla Firefox.

Known Usage

No public information

False Positives

No known false positives


Cisco Talos Intelligence Group

Rule Groups

No rule groups


Additional Links

Rule Vulnerability

CVE Additional Information

This product uses data from the NVD API but is not endorsed or certified by the NVD.
Loading description

MITRE ATT&CK Framework

Tactic: Initial Access

Technique: Drive-by Compromise

For reference, see the MITRE ATT&CK vulnerability types here: