Mozilla Thunderbird Could Allow for Arbitrary Code Execution

Fortify Security Team
Oct 15, 2021

Multiple vulnerabilities have been identified in Mozilla Thunderbird, the most severe of which could allow for arbitrary code execution. Mozilla Thunderbird is an email client. 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: There are currently no reports of these vulnerabilities being exploited in the wild.

SYSTEMS AFFECTED:

  • Mozilla Thunderbird versions prior to 91.2

RISK:

Government:

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

Businesses:

  • Large and medium business entities: Medium
  • Small business entities: Medium

Home users: Low

TECHNICAL SUMMARY:

Multiple vulnerabilities have been identified in Mozilla Thunderbird, the most severe of which could allow for arbitrary code execution. In general, these flaws cannot be exploited through email in the Thunderbird product because scripting is disabled when reading mail, but are potentially risks in browser or browser-like contexts. Details of the vulnerabilities are as follows:

  • Two vulnerabilities that could be exploited to run arbitrary code (CVE-2021-38500, CVE-2021-38501)
  • A downgrade attack that could allow a MITM to take control of the authenticated session to execute SMTP commands (CVE-2021-38502)
  • Two vulnerabilities that could result in memory corruption and a potentially exploitable crash (CVE-2021-38496, CVE-2021-38498)
  • A vulnerability that allowed for spoofing attacks (CVE-2021-38497)
  • A vulnerability that allowed for a potential memory leak (CVE-2021-32810)

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.

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.
  • 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 Foundation:

https://www.mozilla.org/en-US/security/advisories/mfsa2021-47/

CVE:

https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-38502

https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-38501

https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-38500

https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-38498

https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-38497

https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-38496

https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-32810

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