CVE-2016-5136

CVE: CVE-2016-5136
CWE:
- 416
bugs:
- 625393
repo: 
vccs:
- note: 
  commit: 
fixes:
- note: "It's interesting to note how quick this patch came for the fix. The patches
    added new logic that based on their comments appear to be temporary as it will
    be replaced by simpler and cleaner logic to handle stale pointers. New tests were
    also added in their testing config. \n"
  commit: a80776332fd8c99b58beab5d91a6675e85013628
bounty:
  date: '2016-07-20 14:48:00.000000000 -04:00'
  amount: 1000.0
  references:
  - http://chromereleases.googleblog.com/2016/07/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: 
    applies: false
  least_privilege:
    note: "Least privilege applies because if the user doesn't have access to memory
      that may get freed or the object after it's been freed, it can serve as a deterrent
      to this type of vulnerability. \n"
    applies: true
  native_wrappers:
    note: 
    applies: false
  defense_in_depth:
    note: 
    applies: false
  secure_by_default:
    note: 
    applies: false
  environment_variables:
    note: 
    applies: false
  security_by_obscurity:
    note: 
    applies: false
  frameworks_are_optional:
    note: 
    applies: false
reviews:
- 2158683002
- 2155863003
- 2134613002
- 2116923002
upvotes: 
mistakes:
  answer: "After spending some time reading through the discussions held on the bug
    as well as looking through a plethora of commits, \nI feel like it was roughly
    a design mistake that led to the vulnerability. As no code was really deleted,
    just another variable\nwas added in the file along with some lines to deal with
    said variable in terms of handling the script.  I also feel that a lot\nof Use
    After Free vulnerabilities are caused by a combination of coding mistakes and
    design mistakes. If you don't specifically\ndesign your code or functions to account
    for it, it is easy to code in a way that leaves room for this vulnerability to
    happen. \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: '2016-07-23'
subsystem:
  name: Extensions
  answer: The subsystem the source code files are in is the Extensions system.
  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"
vccs_note: "the fix was a refactoring so its hard to say if there was truly a VCC
  especially after digging\nthrough the history of the file and noticing that this
  unaccounting for was missing from the start. \n"
discovered:
  date: '2016-07-02'
  answer: "It's not clear how the project member (tag of user who submitted bug issue)
    discovered it.\nMy conjecture is the project member manually discovered this as
    he was hunting in this subsystem but\nthat is simply conjecture.  \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: "Referencing memory after it has been freed can lead to a variety of
  behaviors including crashing and corrupting data. \n\nIn this specific CVE, when
  an extension is loaded or unloaded by the application, the content\nof these scripts
  are unregistered. If this happens in the middle of an injection, the freed addresses\nof
  these unregistered scripts are accessed causing a use after free vulnerability causing
  a crash. \n"
unit_tested:
  fix: true
  code: true
  note: "As the unit tests were not changed further after the initial addition of
    the unit test. \nThe unit test was not further improved \n"
  answer: "Yes automated unit tests were involved in this vulnerability. However,
    in this case a new test needed to be added to \nconsider this new scenario which
    causes this bug.\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: "I really don't think there was any major events in the history of this.\nSuprisingly,
    the timeline of the find and fix of this bug was around 2 days,\nand in this time
    not much notable happened. \n"
  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: The content of it itself wasn't too interesting but the comments on the
      commit on https://codereview.chromium.org/2116923002/diff/20001/extensions/renderer/user_script_injector.cc
      is interesting as it is pointed out the fix isn't the cleanest or simplest fix
      but they went with it anyways but said they were going to fix it right away
      anyways.
    commit: a80776332fd8c99b58beab5d91a6675e85013628
  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.