CVE-2015-6762

CVE: CVE-2015-6762
CWE:
- 346
- 254
bugs:
- 512678
repo: https://chromium.googlesource.com/chromium/src/
vccs:
- note: "The vulnerability-contributing commit was the implementation of Cross-origin\nResource
    Sharing for downloadable fonts. This implementation omitted handling \nof redirected
    fonts, which lead to this vulnerability existing. This commit \nwas a resolution
    to bug report 286681, which called for downloadable fonts to \nbe subject to CORS.
    \n"
  commit: d90417752a2b8976cc4839418cd1ec1893c8d054
fixes:
- note: "The fix for the vulnerability did not require a significant rework to the
    \ncode. It required the removal of code that checked for the Same-origin \npolicy
    violations. The code now just sets the security policy on all font\nrequests.
    \n"
  commit: 212b92858f0ae007c90abd10b40ba805a13af43c
bounty:
  date: '2015-10-13 13:48:00.000000000 -04:00'
  amount: 500.0
  references:
  - http://chromereleases.googleblog.com/2015/10/stable-channel-update.html
lessons:
  yagni:
    note: 
    applies: 
  question: |
    Are there any common lessons we have learned from class that apply to this
    vulnerability? In other words, could this vulnerability serve as an example
    of one of those lessons?

    Leave "applies" blank or put false if you did not see that lesson (you do
    not need to put a reason). Put "true" if you feel the lesson applies and put
    a quick explanation of how it applies.

    Don't feel the need to claim that ALL of these apply, but it's pretty likely
    that one or two of them apply.

    If you think of another lesson we covered in class that applies here, feel
    free to give it a small name and add one in the same format as these.
  serial_killer:
    note: 
    applies: 
  complex_inputs:
    note: 
    applies: 
  distrust_input:
    note: "The principal behind the Single-origin policy is distrusting inputs into
      \nthe Web Browser. In this case, it is to distrust of the font that is \nloaded
      into the web browser from a different origin. \n"
    applies: true
  least_privilege:
    note: 
    applies: 
  native_wrappers:
    note: 
    applies: 
  defense_in_depth:
    note: "The solution to the vulnerability is an example of defense in depth through\nthe
      strict enforcement of Single-origin policy. This vulnerability is a low \nrisk;
      however, addressing the vulnerability prevents an attack vector that \ncould
      effect components downstream.  \n"
    applies: true
  secure_by_default:
    note: 
    applies: 
  environment_variables:
    note: 
    applies: 
  security_by_obscurity:
    note: 
    applies: 
  frameworks_are_optional:
    note: 
    applies: 
reviews:
- 1256403002
- 1281843002
- 1250793008
upvotes: 
mistakes:
  answer: "The defect that caused this vulnerability is primarily from a coding mistake.
    \nAccording to the bug reports and commit messages, it is evident that CORs \nhandling
    of remote fonts are a requirement. Additionally, the fix did not \nrequire a significant
    rework of the code, therefore it was not a significant \noversight in the system
    architecture. The original author just had a \nmisunderstanding how to effectively
    implement CORS. \n"
  question: |
    In your opinion, after all of this research, what mistakes were made that
    led to this vulnerability? Coding mistakes? Design mistakes?
    Maintainability? Requirements? Miscommunications?

    Look at the CWE entry for this vulnerability and examine the mitigations
    they have written there. Are they doing those? Does the fix look proper?

    Use those questions to inspire your answer. Don't feel obligated to answer
    every one. Write a thoughtful entry here that those ing the software
    engineering industry would find interesting.
announced: '2015-10-15 06:59:08.623000000 -04:00'
subsystem:
  name: Blink
  answer: The vulnerability was in the CSS implementation of the Blink rendering engine.
  question: |
    What subsystems was the mistake in?

    Look at the path of the source code files code that were fixed to get
    directory names. Look at comments in the code. Look at the bug reports how
    the bug report was tagged. Examples: "clipboard", "gpu", "ssl", "speech", "renderer"
discovered:
  date: '2015-07-22'
  answer: "This vulnerability was found by a contributor who submitted to a bug bounty
    \nprogram. Due to the nature of this vulnerability, the submitter created \nwebsites
    with JavaScript designed to test and showcase the bug. \n"
  google: false
  contest: true
  question: |
    How was this vulnerability discovered?

    Go to the bug report and read the conversation to find out how this was
    originally found. Answer in longform below in "answer", fill in the date in
    YYYY-MM-DD, and then determine if the vulnerability was found by a Google
    employee (you can tell from their email address). If it's clear that the
    vulenrability was discovered by a contest, fill in the name there.

    The "automated" flag can be true, false, or nil.
    The "google" flag can be true, false, or nil.

    If there is no evidence as to how this vulnerability was found, then you may
    leave the entries blank except for "answer". Write down where you looked in "answer".
  automated: false
description: "This vulnerability is an example of a circumvention of the Same-origin
  \nimplementation on Google Chrome. This vulnerability occurred in the manner \nGoogle
  Chrome handled Cascading Style Sheets (CSS); more specifically, it \noccurred in
  the code that fetched the fonts resource for a web page. The \nomission of the use
  of the Cross-origin Resource Sharing (CORS) algorithm, \nallows an attacker to bypass
  the single origin policy through JavaScript \nthat requests a font through a redirect.
  The Google Chrome panel did believe\nthat this vulnerability did not bypassed anything
  other than DRM. \n"
unit_tested:
  fix: true
  code: true
  answer: "Unit tests where involved in this code segment. The contributor also\nadded
    an unit test to check for this condition. \n"
  question: |
    Were automated unit tests involved in this vulnerability?
    Was the original code unit tested, or not unit tested? Did the fix involve
    improving the automated tests?

    For the "code" answer below, look not only at the fix but the surrounding
    code near the fix and determine if and was there were unit tests involved
    for this module.

    For the "fix" answer below, check if the fix for the vulnerability involves
    adding or improving an automated test to ensure this doesn't happen again.
major_events:
  answer: "This code segment featured steady development during the timeline of events.
    \nOne key event what the change of the namespace name for this module. It is \nnot
    likely that this effected the vulnerability. \n"
  events:
  - date: '2014-07-18'
    name: Namespace change from WebCore to Blink
  - date: 
    name: 
  question: |
    Please record any major events you found in the history of this
    vulnerability. Was the code rewritten at some point? Was a nearby subsystem
    changed? Did the team change?

    The event doesn't need to be directly related to this vulnerability, rather,
    we want to capture what the development team was dealing with at the time.
curation_level: 0
CWE_instructions: |
  Please go to cwe.mitre.org and find the most specific, appropriate CWE entry
  that describes your vulnerability. (Tip: this may not be a good one to start
  with - spend time understanding this vulnerability before making your choice!)
bounty_instructions: |
  If you came across any indications that a bounty was paid out for this
  vulnerability, fill it out here. Or correct it if the information already here
  was wrong. Otherwise, leave it blank.
interesting_commits:
  answer: "There were not any interesting commits in the timeline between the VCCS
    and \nthe VCC. Bug report 426089 was reported during this timeline and it pertained\nto
    the CORS implementation. The report cited incorrect headers in the HTTP \nrequests;
    however, this bug report was resolved as “WontFix” due to the \ndifficulty of
    reproduction and its low priority. \n"
  commits:
  - note: 
    commit: 
  - note: 
    commit: 
  question: |
    Are there any interesting commits between your VCC(s) and fix(es)?

    Write a brief (under 100 words) description of why you think this commit was
    interesting in light of the lessons learned from this vulnerability. Any
    emerging themes?

    If there are no interesting commits, demonstrate that you completed this section by explaining what happened between the VCCs and the fix.
curated_instructions: |
  If you are manually editing this file, then you are "curating" it. Set the
  entry below to "true" as soon as you start. This will enable additional
  integrity checks on this file to make sure you fill everything out properly.
  If you are a student, we cannot accept your work as finished unless curated is
  set to true.
upvotes_instructions: |
  For the first round, ignore this upvotes number.

  For the second round of reviewing, you will be giving a certain amount of
  upvotes to each vulnerability you see. Your peers will tell you how
  interesting they think this vulnerability is, and you'll add that to the
  upvotes score on your branch.
announced_instructions: |
  Was there a date that this vulnerability was announced to the world? You can
  find this in changelogs, blogs, bug reports, or perhaps the CVE date. A good
  source for this is Chrome's Stable Release Channel
  (https://chromereleases.googleblog.com/).
  Please enter your date in YYYY-MM-DD format.
fixes_vcc_instructions: |
  Please put the commit hash in "commit" below (see my example in
  CVE-2011-3092.yml). Fixes and VCCs follow the same format.
description_instructions: |
  You can get an initial description from the CVE entry on cve.mitre.org. These
  descriptions are a fine start, but they can be kind of jargony.

  Rewrite this description in your own words. Make it interesting and easy to
  read to anyone with some programming experience. We can always pull up the NVD
  description later to get more technical.

  Try to still be specific in your description, but remove Chromium-specific
  stuff. Remove references to versions, specific filenames, and other jargon
  that outsiders to Chromium would not understand. Technology like "regular
  expressions" is fine, and security phrases like "invalid write" are fine to
  keep too.