Multiple Vulnerabilities in Mozilla Firefox Could Allow for Arbitrary Code Execution

Summary

Multiple vulnerabilities have been discovered in Mozilla Firefox and Firefox Extended Support Release (ESR), the most severe of which could allow for arbitrary code execution. Successful exploitation of the most severe of these vulnerabilities could allow for arbitrary code execution. Depending on the privileges associated with the user, an attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. Users whose accounts are configured to have fewer user rights on the system could be less impacted than those who operate with administrative user rights.

Threat Intelligence

Mozilla reports that these two vulnerabilities are being exploited in the wild.

Systems Affected

• Firefox versions prior to 74.0.1
• Firefox ESR versions prior to 68.6.1

Risk

Government:

• Large and medium government entities: High
• Small government entities: Medium

Businesses:

• Large and medium government entities: High
• Small government entities: Medium

Home users: Low

Technical Details

Multiple vulnerabilities have been discovered in Mozilla Firefox and Firefox Extended Support Release (ESR), the most severe of which could allow for arbitrary code execution. Details of the vulnerabilities are as follows:

• Under certain conditions, when running the nsDocShell destructor, a race condition can cause a use-after-free. (CVE-2020-6819)
• Under certain conditions, when handling a ReadableStream, a race condition can cause a use-after-free. (CVE-2020-6820)

Recommendations

We recommend the following actions be taken:

• Apply appropriate updates provided by Mozilla to vulnerable systems, immediately after appropriate testing. 
• Run all software as a non-privileged user (one without administrative privileges) to diminish the effects of a successful attack. 
• Remind users not to visit un-trusted websites or follow links provided by unknown or un-trusted sources. 
• Inform and educate users regarding the threats posed by hypertext links contained in emails or attachments especially from un-trusted sources. 
• Apply the Principle of Least Privilege to all systems and services.

References

Mozilla

Bleeping Computer

CVE: visit here and here

Reporting

The NJCCIC encourages recipients who discover signs of malicious cyber activity to contact the NJCCIC via the cyber incident report form by clicking here.

Please do not hesitate to contact the NJCCIC at njccic@cyber.nj.gov with any questions.