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Multiple Vulnerabilities in Mozilla Firefox Could Allow for Arbitrary Code Execution

MS-ISAC ADVISORY NUMBER:

2017-056

DATE(S) ISSUED:

06/13/2017

OVERVIEW:

Multiple vulnerabilities have been identified in Mozilla Firefox and Firefox Extended Support Release (ESR), 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 is no evidence of these vulnerabilities being exploited in the wild.

SYSTEMS AFFECTED:

  • Mozilla Firefox versions prior to 54
  • Firefox ESR versions prior to 52.2

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 Firefox and Firefox Extended Support Release (ESR).

  • A use-after-free vulnerability with the frameloader during tree reconstruction while regenerating CSS layout when attempting to use a node in the tree that no longer exists. This results in a potentially exploitable crash. (CVE-2017-5472)
  • A use-after-free vulnerability when using an incorrect URL during the reloading of a docshell. This results in a potentially exploitable crash. (CVE-2017-7749)
  • A use-after-free vulnerability during video control operations when a element holds a reference to an older window if that window has been replaced in the DOM. This results in a potentially exploitable crash. (CVE-2017-7750)
  • A use-after-free vulnerability with content viewer listeners that results in a potentially exploitable crash. (CVE-2017-7751)
  • A use-after-free vulnerability during specific user interactions with the input method editor (IME) in some languages due to how events are handled. This results in a potentially exploitable crash but would require specific user interaction to trigger. (CVE-2017-7752)
  • An out-of-bounds read in WebGL with a maliciously crafted ImageInfo object during WebGL operations. (CVE-2017-7754)
  • The Firefox installer on Windows can be made to load malicious DLL files stored in the same directory as the installer when it is run. This allows privileged execution if the installer is run with elevated privileges. (CVE-2017-7755)
  • A use-after-free and use-after-scope vulnerability when logging errors from headers for XML HTTP Requests (XHR). This could result in a potentially exploitable crash. (CVE-2017-7756)
  • A use-after-free vulnerability in IndexedDB when one of its objects is destroyed in memory while a method on it is still being executed. This results in a potentially exploitable crash. (CVE-2017-7757)
  • A number of security vulnerabilities in the Graphite 2 library including out-of-bounds reads, buffer overflow reads and writes, and the use of uninitialized memory. These issues were addressed in Graphite 2 version 1.3.10. (CVE-2017-7778)
  • An out-of-bounds read vulnerability with the Opus encoder when the number of channels in an audio stream changes while the encoder is in use. (CVE-2017-7758)
  • Android intent URLs given to Firefox for Android can be used to navigate from HTTP or HTTPS URLs to local file: URLs, allowing for the reading of local data through a violation of same-origin policy. (CVE-2017-7759)
  • The Mozilla Windows updater modifies some files to be updated by reading the original file and applying changes to it. The location of the original file can be altered by a malicious user by passing a special path to the callback parameter through the Mozilla Maintenance Service, allowing the manipulation of files in the installation directory and privilege escalation by manipulating the Mozilla Maintenance Service, which has privileged access. (CVE-2017-7760)
  • The Mozilla Maintenance Service helper.exe application creates a temporary directory writable by non-privileged users. When this is combined with creation of a junction (a form of symbolic link), protected files in the target directory of the junction can be deleted by the Mozilla Maintenance Service, which has privileged access. (CVE-2017-7761)
  • When entered directly, Reader Mode did not strip the username and password section of URLs displayed in the addressbar. This can be used for spoofing the domain of the current page. (CVE-2017-7762)
  • Default fonts on OS X display some Tibetan characters as whitespace. When used in the addressbar as part of an IDN this can be used for domain name spoofing attacks. (CVE-2017-7763)
  • Characters from the "Canadian Syllabics" unicode block can be mixed with characters from other unicode blocks in the addressbar instead of being rendered as their raw "punycode" form, allowing for domain name spoofing attacks through character confusion. The current Unicode standard allows characters from "Aspirational Use Scripts" such as Canadian Syllabics to be mixed with Latin characters in the "moderately restrictive" IDN profile. We have changed Firefox behavior to match the upcoming Unicode version 10.0 which removes this category and treats them as "Limited Use Scripts." (CVE-2017-7764)
  • The "Mark of the Web" was not correctly saved on Windows when files with very long names were downloaded from the Internet. Without the Mark of the Web data, the security warning that Windows displays before running executables downloaded from the Internet is not shown. (CVE-2017-7765)
  • An attack using manipulation of updater.ini contents, used by the Mozilla Windows Updater, and privilege escalation through the Mozilla Maintenance Service to allow for arbitrary file execution and deletion by the Maintenance Service, which has privileged access. (CVE-2017-7766)
  • The Mozilla Maintenance Service can be invoked by an unprivileged user to overwrite arbitrary files with junk data using the Mozilla Windows Updater, which runs with the Maintenance Service's privileged access. (CVE-2017-7767)
  • The Mozilla Maintenance Service can be invoked by an unprivileged user to read 32 bytes of any arbitrary file on the local system by convincing the service that it is reading a status file provided by the Mozilla Windows Updater. The Mozilla Maintenance Service executes with privileged access, bypassing system protections against unprivileged users. (CVE-2017-7768)
  • Mozilla developers and community members Mats Palmgren, Philipp, Byron Campen, Christian Holler, Gary Kwong, Benjamin Bouvier, Bob Clary, Jon Coppeard, and Michael Layzell reported memory safety bugs present in Firefox 53. 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-2017-5471)
  • Mozilla developers and community members Tyson Smith, Mats Palmgren, Philipp, Masayuki Nakano, Christian Holler, Andrew McCreight, Gary Kwong, AndrĂ© Bargull, Carsten Book, Jesse Schwartzentruber, Julian Hector, Marcia Knous, Ronald Crane, and Nils Ohlmeier reported memory safety bugs present in Firefox 53 and Firefox ESR 52.1. 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-2017-5470)

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.

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