angler-fishThe Vulnerability History Project

CVE-2014-1745

This was a vulnerability in the SVG implementation of Blink, Chrome's rendering engine, that allowed for a denial of service attack. A change was made to enhance the performance of the implementation, and allow the browser to selectively update font rules of a page, rather than having to reload the entire FontSelector when things are changed. The vulnerability was caused by the removal method, wherein not all references to a removed element were cleared, even after said element's memory was freed. The program would still attempt to use these elements, and would either crash or have unspecified behavior.


After analyzing the bug report and comments that followed, as well as the discussion on the VCC, it seems clear that this vulnerability was a simple coding mistake. The author of the VCC simply overlooked a reference in a major enhancement to the renderer, and fixed it after the vulnerability was reported.
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CVE: CVE-2014-1745
CWE:
- 416
- 399
bugs:
- 346192
repo: 
vccs:
- note: Introduced as part of a performance enhancement
  commit: d7df607030c7f32637e41a1ad00d3fd2bf94db1b
fixes:
- note: ''
  commit: 9f88c15fbcd76321cfeedf3f4792534cb6041c4e
bounty:
  date: '2014-05-20'
  amount: 1000.0
  references:
  - http://chromereleases.googleblog.com/2014/05/stable-channel-update_20.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: 
    applies: 
  least_privilege:
    note: 
    applies: 
  native_wrappers:
    note: 
    applies: 
  defense_in_depth:
    note: 
    applies: 
  secure_by_default:
    note: 
    applies: 
  environment_variables:
    note: 
    applies: 
  security_by_obscurity:
    note: 
    applies: 
  frameworks_are_optional:
    note: 
    applies: 
reviews:
- 176853009
upvotes: 1
mistakes:
  answer: "After analyzing the bug report and comments that followed, as well as the\ndiscussion
    on the VCC, it seems clear that this vulnerability was a simple\ncoding mistake.\n\nThe
    author of the VCC simply overlooked a reference in a major enhancement\nto the
    renderer, and fixed it after the vulnerability was reported. \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: '2014-05-20'
subsystem:
  name: renderer
  answer: The mistake was in Blink, chrome's 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: '2014-02-24'
  answer: |
    This vulnerability was discovered by Atte Kettunen of the Oulu University
    Secure Programming Group.
  google: false
  contest: 
  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 was a vulnerability in the SVG implementation of Blink, Chrome's\nrendering
  engine, that allowed for a denial of service attack.\n\nA change was made to enhance
  the performance of the implementation, and allow\nthe browser to selectively update
  font rules of a page, rather than having\nto reload the entire FontSelector when
  things are changed. The vulnerability\nwas caused by the removal method, wherein
  not all references to a removed\nelement were cleared, even after said element's
  memory was freed. \n\nThe program would still attempt to use these elements, and
  would either crash\nor have unspecified behavior. \n"
unit_tested:
  fix: true
  code: true
  answer: "The existing unit tests did not cover this case explicitly, but more were
    \nadded after the fix to ensure that the vulnerability does not return. \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: There were no major events observed in this time.
  events:
  - date: 
    name: 
  - 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: 1
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 no interesting commits between the VCC and the fix; the fix\ncame
    a mere 10 days after the VCC. \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.

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