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Multiple Vulnerabilities in Mozilla Thunderbird Could Allow for Arbitrary Code Execution

MS-ISAC ADVISORY NUMBER:

2017-075

DATE(S) ISSUED:

08/21/2017

OVERVIEW:

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 52.3

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:

Mozilla has confirmed the following vulnerabilities in Thunderbird versions prior to 52.3

  • A use-after-free vulnerability can occur in WebSockets when the object holding the connection is freed before the disconnection operation is finished. This results in an exploitable crash. (CVE-2017-7800)
  • A use-after-free vulnerability can occur while re-computing layout for a marquee element during window resizing where the updated style object is freed while still in use. This results in a potentially exploitable crash. CVE-2017-7801)
  • A use-after-free vulnerability can occur when an editor DOM node is deleted prematurely during tree traversal while still bound to the document. This results in a potentially exploitable crash. (CVE-2017-7809)
  • A use-after-free vulnerability can occur when reading an image observer during frame reconstruction after the observer has been freed. This results in a potentially exploitable crash. (CVE-2017-7784)
  • A use-after-free vulnerability can occur when manipulating the DOM during the resize event of an image element. If these elements have been freed due to a lack of strong references, a potentially exploitable crash may occur when the freed elements are accessed. CVE-2017-7802)
  • A buffer overflow can occur when manipulating Accessible Rich Internet Applications (ARIA) attributes within the DOM. This results in a potentially exploitable crash. (CVE-2017-7785)
  • A buffer overflow can occur when the image renderer attempts to paint non-displayable SVG elements. This results in a potentially exploitable crash. (CVE-2017-7786)
  • An out-of-bounds read occurs when applying style rules to pseudo-elements, such as ::first-line, using cached style data. (CVE-2017-7753)
  • Same-origin policy protections can be bypassed on pages with embedded iframes during page reloads, allowing the iframes to access content on the top level page, leading to information disclosure. (CVE-2017-7787)
  • A mechanism that uses AppCache to hijack a URL in a domain using fallback by serving the files from a sub-path on the domain. This has been addressed by requiring fallback files be inside the manifest directory. (CVE-2017-7807)
  • A buffer overflow will occur when viewing a certificate in the certificate manager if the certificate has an extremely long object identifier (OID). This results in a potentially exploitable crash. (CVE-2017-7792)
  • The destructor function for the WindowsDllDetourPatcher class can be re-purposed by malicious code in concert with another vulnerability to write arbitrary data to an attacker controlled location in memory. This can be used to bypass existing memory protections in this situation. (CVE-2017-7804)
  • On pages containing an iframe, the data: protocol can be used to create a modal alert that will render over arbitrary domains following page navigation, spoofing of the origin of the modal alert from the iframe content. (CVE-2017-7791)
  • An error in the WindowsDllDetourPatcher where a RWX ("Read/Write/Execute") 4k block is allocated but never protected, violating DEP protections. (CVE-2017-7782)
  • When a page’s content security policy (CSP) header contains a sandbox directive, other directives are ignored. This results in the incorrect enforcement of CSP. (CVE-2017-7803)
  • Memory safety bugs showed evidence of memory corruption and we presume that with enough effort that some of these could be exploited to run arbitrary code. (CVE-2017-7779)

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.

RECOMENDATIONS:

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:

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