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Multiple Vulnerabilities in Mozilla Firefox Could Allow for Remote Code Execution

MS-ISAC ADVISORY NUMBER:

2020-061

DATE(S) ISSUED:

05/06/2020

OVERVIEW:

Multiple vulnerabilities have been discovered in Mozilla Firefox and Mozilla Firefox ESR, the most severe of which could allow for remote code execution. Mozilla Firefox is a web browser used to access the Internet. Mozilla Firefox ESR is a version of the web browser intended to be deployed in large organizations. Successful exploitation of the most severe of these vulnerabilities could allow for remote code execution in the context of the logged-on user. 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:

There are currently no reports of these vulnerabilities being exploited in the wild.

SYSTEMS AFFECTED:

  • Mozilla Firefox prior to 76
  • Mozilla Firefox ESR prior to 68.8

RISK:

Government:
  • Large and medium government entities: HIGH
  • Small government entities: MEDIUM
Businesses:
  • Large and medium business entities: HIGH
  • Small business entities: MEDIUM
Home Users:
LOW

TECHNICAL SUMMARY:

Multiple vulnerabilities have been discovered in Mozilla Firefox and Mozilla Firefox ESR, the most severe of which could allow for remote code execution. These vulnerabilities can be exploited if a user visits a specially crafted web page. Details of these vulnerabilities are as follows:

  • One user-after-free vulnerability exists when shutdown code for Web Worker was used. (CVE-2020-12387)
  • Two sandbox escape vulnerabilities exist with Firefox’s content processes that did not sufficiently lockdown access control. (CVE-2020-12388, CVE-2020-12389)
  • One buffer overflow vulnerability exists wen parsing and validating SCTP chunks in WebRTC. (CVE-2020-6831)
  • One security check vulnerability exits that could cause incorrect security checks with incorrect origin serialization of URLs with IPv6 (CVE-2020-12390)
  • One vulnerability exits that allows for execution of blocked scripts for documents formed using data: URLs. (CVE-2020-12391)
  • Two vulnerabilities exist within the ‘Copy as cURL’ feature within Firefox that can cause local file access and command injection. (CVE-2020-12393, CVE-2020-12392)
  • One spoofing vulnerability exists within Firefox’s location bar implementation. (CVE-2020-12394)
  • Two memory corruption vulnerabilities exist that could cause memory corruption and execution of arbitrary code. (CVE-2020-12395, CVE-2020-12396)

Successful exploitation of the most severe of these vulnerabilities could allow for remote code execution in the context of the logged-on user. 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.

RECOMMENDATIONS:

We recommend the following actions be taken:

  • Apply appropriate patches 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.
  • Apply the Principle of Least Privilege to all systems and services

REFERENCES:

Information Hub : Advisories


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Pencil Media mention 27 May 2020
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