CVE-2017-7843 : Security Advisory and Response

A security vulnerability in Firefox ESR and Firefox versions allowed web workers to save data to IndexedDB during Private Browsing mode, compromising user privacy.

Understanding CVE-2017-7843

By utilizing Private Browsing mode, a web worker could store lasting information to IndexedDB, potentially identifying users uniquely.

What is CVE-2017-7843?

This vulnerability impacted Firefox ESR versions prior to 52.5.2 and Firefox versions prior to 57.0.1, allowing stored data to persist across multiple Private Browsing mode sessions.

The Impact of CVE-2017-7843

The flaw enabled web workers to write persistent data to IndexedDB, compromising user privacy and potentially allowing user fingerprinting.

Technical Details of CVE-2017-7843

This section provides more in-depth technical insights into the vulnerability.

Vulnerability Description

When Private Browsing mode was used, web workers could write persistent data to IndexedDB, violating the expected behavior of Private Browsing mode.

Affected Systems and Versions

Firefox ESR versions prior to 52.5.2
Firefox versions prior to 57.0.1

Exploitation Mechanism

The vulnerability allowed web workers to bypass the restrictions of Private Browsing mode, storing data in IndexedDB that persisted across sessions.

Mitigation and Prevention

Protecting systems from CVE-2017-7843 requires immediate actions and long-term security practices.

Immediate Steps to Take

Update Firefox ESR to version 52.5.2 or later
Update Firefox to version 57.0.1 or later
Clear IndexedDB data after each Private Browsing session

Long-Term Security Practices

Regularly update browsers to the latest versions
Educate users on the importance of clearing browsing data

Patching and Updates

Apply security patches provided by Mozilla to address the vulnerability