MS-ISAC CYBERSECURITY ADVIOSRY – Multiple Vulnerabilities in Mozilla Firefox Could Allow for Arbitrary Code Execution – PATCH: NOW – TLP: WHITE

MS-ISAC ADVISORY NUMBER:

2018-139

DATE(S) ISSUED:

12/11/2018

OVERVIEW:

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. 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 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 Firefox versions prior to 64
• Mozilla Firefox ESR version prior to 60.4

RISK:

TECHNICAL 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. Details of the vulnerabilities are as follows:

• A buffer overflow and out-of-bounds read can occur in TextureStorage11 within the ANGLE graphics library, used for WebGL content. This results in a potentially exploitable crash. (CVE-2018-17466)
• A buffer overflow can occur in the Skia library during buffer offset calculations with hardware accelerated canvas 2D actions due to the use of 32-bit calculations instead of 64-bit. This results in a potentially exploitable crash. (CVE-2018-18493)
• A buffer overflow occurs when drawing and validating elements with the ANGLE graphics library, used for WebGL content, when working with the VertexBuffer11 module. This results in a potentially exploitable crash. (CVE-2018-12407)
• A potential vulnerability leading to an integer overflow can occur during buffer size calculations for images when a raw value is used instead of the checked value. This can lead to an out-of-bounds write. (CVE-2018-18498)
• A potential vulnerability leading to an integer overflow can occur during buffer size calculations for images when a raw value is used instead of the checked value. This leads to a possible out-of-bounds write. (CVE-2018-18498)
• A same-origin policy violation allowing the theft of cross-origin URL entries when using the Javascript location property to cause a redirection to another site using performance.getEntries(). This is a same-origin policy violation and could allow for data theft. (CVE-2018-18494)
• A use-after-free vulnerability can occur after deleting a selection element due to a weak reference to the select element in the options collection. This results in a potentially exploitable crash. (CVE-2018-18492)
• Mozilla developers and community members Alex Gaynor, André Bargull, Boris Zbarsky, Christian Holler, Jan de Mooij, Jason Kratzer, Jed Davis, Philipp, Ronald Crane, Natalia Csoregi, and Paul Theriault reported memory safety bugs present in Firefox 63. Some of these 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-2018-12406)
• Mozilla developers and community members Christian Holler, Diego Calleja, Andrew McCreight, Jon Coppeard, Natalia Csoregi, Nicolas B. Pierron, and Tyson Smith reported memory safety bugs present in Firefox 63 and Firefox ESR 60.3. Some of these 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-2018-12405)
• Limitations on the URIs allowed to WebExtensions by the browser.windows.create API can be bypassed when a pipe in the URL field is used within the extension to load multiple pages as a single argument. This could allow a malicious WebExtension to opened privileged about: or file: locations. (CVE-2018-18497)
• WebExtension content scripts can be loaded into about: pages in some circumstances, in violation of the permissions granted to extensions. This could allow an extension to interfere with the loading and usage of these pages and use capabilities that were intended to be restricted from extensions. (CVE-2018-18495)
• When the RSS Feed preview about:feeds page is framed within another page, it can be used in concert with scripted content for a clickjacking attack that confuses users into downloading and executing an executable file from a temporary directory. Note: This issue only affects Windows operating systems. Other operating systems are not affected. (CVE-2018-18496)

Successful exploitation of the most severe of these vulnerabilities could allow for arbitrary code execution. Depending on the privileges associated with the usergrep 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.

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