angler-fishThe Vulnerability History Project

CVE-2015-6774

The vulnerability was found in one of the functions relating to loading time within the Chrome's renderer subsystem. Modification of a pointer through javascript can give remote attackers the ability to cause denial of service. Specifically, when the pointer used for reporting load times data is modified by javascript, the use of unexpected values can occur. To do so, a remote use would have to create specific content that when loaded by the target system, will execute arbitrary code on the target user's system.


The mistake made was assuming the type of the input before carrying out execution of the variable. When working in a programming language that has the programmer handling memory, having explicitly written code prevents some of these vulnerablities. Based on the CWE entry, to mitigate such vulnerability, one should try to use a language that provides automatic memory management. This was not done because execution should be optimal when it comes to speed and to do that, carrying out your own memory management gives more flexibility. For the implementation fix, the programmer did set the pointer to null before carrying out further implementation of the pointer. This would seem to be the proper fix to a problem such as this.
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CVE: CVE-2015-6774
CWE:
- 416
bugs:
- 549251
repo: https://chromium.googlesource.com/chromium/src/+/4026d85fcded8c4ee5113cb1bd1a7e8149e03827
vccs:
- note: They were working on extracting load times from the web data source
  commit: ed3fb034eb4b7da69bbc4f3e3da47093dabc481e
fixes:
- note: ''
  commit: 4026d85fcded8c4ee5113cb1bd1a7e8149e03827
bounty:
  date: '2015-12-01 14:43:00.000000000 -05:00'
  amount: 5000.0
  references:
  - http://chromereleases.googleblog.com/2015/12/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: "It applies here because you want to ensure that the variables coming in\nare
      not what you expect them to be and explicitly check for that. Setting a \nvariable
      to null rather than assuming it is null prevents usage of free memory. \n"
    applies: true
  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:
- 1425373003
- 1422753007
upvotes: 2
mistakes:
  answer: "The mistake made was assuming the type of the input before carrying out
    execution of\nthe variable. When working in a programming language that has the
    programmer handling memory,\nhaving explicitly written code prevents some of these
    vulnerablities. \n\nBased on the CWE entry, to mitigate such vulnerability, one
    should try to use a language that \nprovides automatic memory management. This
    was not done because execution should be optimal \nwhen it comes to speed and
    to do that, carrying out your own memory management gives more flexibility.\nFor
    the implementation fix, the programmer did set the pointer to null before carrying
    out further\nimplementation of the pointer. This would seem to be the proper fix
    to a problem such as this.\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 in the software
    engineering industry would find interesting.
announced: '2015-12-05 20:59:11.567000000 -05:00'
subsystem:
  name: renderer
  answer: Based on the description and codereview
  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: '2015-10-30'
  answer: "It was found through a code review and only thing that was mentioned was
    that the \nfunction seemed squished so it was rewritten.\n"
  google: true
  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: "The vulnerability was found in one of the functions relating to loading
  time \nwithin the Chrome's renderer subsystem.\n\nModification of a pointer through
  javascript can give remote attackers the \nability to cause denial of service. Specifically,
  when the pointer used for \nreporting load times data is modified by javascript,
  the use of unexpected \nvalues can occur. To do so, a remote use would have to create
  specific content\nthat when loaded by the target system, will execute arbitrary
  code on the target \nuser's system.\n"
unit_tested:
  fix: false
  code: false
  answer: 'No there was no automated unit tests involved in this vulnerability

    '
  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: "The code was rewritten as it was bulky and needed to be squished \n"
  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 because the only discussion they had
    was one comment,\nstating a refactor of the function to make it shorter. \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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