CVE-2015-1220

CVE: CVE-2015-1220
CWE:
- 146
bugs:
- 437651
repo: 
vccs:
- note: This commit is the last time that the affected code was edited
  commit: 217add8aebf21a09e5bae70843f103e9b51cfdec
fixes:
- note: This commit handles both the files code and the unit tests
  commit: 4f9c9adef4036aff60b734b4a0045c43c320fe1d
bounty:
  date: '2015-03-03 15:53:00.000000000 -05:00'
  amount: 3000.0
  references:
  - http://chromereleases.googleblog.com/2015/03/stable-channel-update.html
lessons:
  yagni:
    note: 
    applies: false
  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: false
  complex_inputs:
    note: 
    applies: false
  distrust_input:
    note: This issue was found in corrupted gifs, or if the first frame of a gif was
      larger than the screen size. If there were more checks in place for proper gifs,
      then this vulnerability would not have been a concern.
    applies: true
  least_privilege:
    note: 
    applies: false
  native_wrappers:
    note: 
    applies: false
  defense_in_depth:
    note: 
    applies: false
  secure_by_default:
    note: After the vulnerability was found and corrected, they added code in to ensure
      that the gifs were appropriately loaded and created. They also added exception
      handling for inappropriately constructed gifs, and do not attempt to load them
      if the sizing is incorrect.
    applies: true
  environment_variables:
    note: 
    applies: false
  security_by_obscurity:
    note: 
    applies: false
  frameworks_are_optional:
    note: 
    applies: false
reviews:
- 868803008
- 813943003
upvotes: 10
mistakes:
  answer: "One thing that I found interesting about this vulnerability is that it
    was found\ntwo months before it was fixed or looked at. Once it was looked at
    and recreated, \nit was labelled high priority and had a larger bounty than other
    common vulnerabilities. \nThis probably could have been done on a quicker schedule,
    but there might have been \na release or some other thing more important in the
    employee's workload.\n\nFrom reading into this vulnerability, this is a common
    issue that many services that\nhave gif loading have. On the Chromium team's internal
    comments, there was mention of \nthis issue also occuring on firefox. I believe
    that this was created by a coding mistake.\nThe team also mentioned that there
    was a quick fix in place that did not cover the edge case\nof this vulnerability-when
    the first frame of the gif is larger than the screen size.\n\nThe CWE associated
    with this vulnerability is concerned with memory use after a free, because\nof
    the error that occurs after the before mentioned issue with gif frame sizes. There
    are two\nsuggested mitigatons in the CWE entry. The first mitigation suggests
    choosing a language that \nprovides automatic memory management. For a engine
    such as blink that is quite large, it is not\nrealistic to rewrite the rendering
    engine in a new language. The second mitigation is to be sure\nto set your variables
    to NULL after they are freed, but even the mitigation strategy mentions \nthat
    this fix may not be very useful if there are multiple of complex data structures,
    and blink\nis a very complicated engine.\n\nHowever, considering they fixed the
    issue at its root cause(mishandling gif decoding), and changed\nthe quick fix,
    it seems like the fix was handled properly. \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: '2015-03-08 20:59:13.327000000 -04:00'
subsystem:
  name: blink
  answer: |
    Blink is chromium's gif renderer and decoder. The vulnerability is focused on
    the decoding of gifs, and all of the source code is found concerning that 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: '2014-11-30'
  answer: "I am unable to see a large amount of data that was generated with the original\nreport
    when google tried to recreate the issue due to a lack of permission. \nThe original
    user that reported the bug did not say much in his post other \nthan the step
    by step guide for recreation. They had a gif that they provided, \nand the aforementioned
    denial of service error.\n"
  google: false
  contest: false
  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: "In Google Chrome, there were multiple occasions where after a memory
  location is freed,\nthe location is then attempted to be used again. In this specific
  vulnerability, a \nlocation used for a GIF decoder is attempted to be used again
  after a gif fails to be\ndecoded. If a remote attacker chooses to attempt to take
  advantage of this vulnerability, \nthey could cause a denial of service for other
  users or other unpredicted behavior. \nThe way that it is anticipated that an attacker
  would take advantage of this is by a \n\"crafted frame size\" in a GIF. Any frame
  size larger than the screen size of a device \ncould cause the broken GIF to triggers
  a bug in the decoding code for the GIF.\n"
unit_tested:
  fix: true
  code: false
  answer: "This code was unit tested after the vulnerability was found and corrected.\nIn
    fact, in what I believe to be the vcc, the author wrote that it was\n'simple refactoring,
    no tests' on the part of the code that they edited. While \nthey did not introduce
    the issue, they would have noticed it earlier had they \nadded tests into the
    framework at that time.\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: 
  events:
  - date: '2014-11-30'
    name: Bug Reported
  - date: '2015-01-07'
    name: Work Started on Vulnerability
  - date: '2015-01-08'
    name: Issue Found
  - date: '2015-01-16'
    name: Fix Added, Merge Failed
  - date: '2015-02-06'
    name: Fix Approved
  - date: '2015-03-03'
    name: Reward Given to Reporter
  - date: '2015-04-23'
    name: Bug Released to Public
  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: 
  commits:
  - note: This commit is interesting because part of the vcc is from refactoring,
      and the writer purposefully did not write tests for it. In previous classwork,
      we learned to always test when refactoring and this proves that.
    commit: 217add8aebf21a09e5bae70843f103e9b51cfdec
  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.