CVE-2015-6779

CVE: CVE-2015-6779
CWE:
- 264
bugs:
- 528505
- 225927
repo: https://chromium.googlesource.com/chromium/src.git@master
vccs:
- note: |
    Two year old known bug, commits were made after that and it is
    unknown why changes were not made. They were trying to fix the context menu
    on pdf files in the dev tool emulator.
  commit: 
fixes:
- note: ''
  commit: 1eefa26e1795192c5a347a1e1e7a99e88c47f9c4
bounty:
  date: '2015-12-01'
  amount: 2000.0
  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: |
      Anything contained within a PDF should not be trusted, since they are unverified
      opened.  While links are not normally an input issue within PDFs, I believe this
      still applies.
    applies: true
  least_privilege:
    note: |
      No one should have the privilege to click links from a pdf document.  Especially
      not common users that can use this privilege maliciously.
    applies: true
  native_wrappers:
    note: 
    applies: 
  defense_in_depth:
    note: 
    applies: 
  secure_by_default:
    note: 'This vulnerability would not have been possible if CSS was used properly.

      '
    applies: true
  environment_variables:
    note: 
    applies: 
  security_by_obscurity:
    note: |
      One of the inital attempts to fix this bug was essentually security by
      obscurity. They just went over the pdf and made the links plaintext so
      users wouldn't click on them, but the error and flaw was still present.
    applies: true
  frameworks_are_optional:
    note: 
    applies: 
reviews:
- 1362433002
upvotes: 2
mistakes:
  answer: "I would say that this vulnerability was a culmination of design mistakes
    and \npotentially poor requirements.  I say this, because a vulerability like
    this\nshould not normally occur.  HTML prohibits this and PDF documents do not
    normally\nallow this behavior.  My guess is that some niche design decision was
    made that\nallowed for this behavior.  It is also fair to say that this design
    decision may\nhave been made due to poor requirements.\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: '2015-12-05'
subsystem:
  name: Browser
  answer: Based on the directory and path of the problem code.
  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: '2015-09-04'
  answer: |
    The exploit was found by ullrich....@gmail.com. The exploit was easily reproducable
    and had immediate security implications, since all an attacker had to do was craft
    a PDF document with a link to bypass scheme restrictions.  Quickly became a moderate
    to high priority fix.
  google: true
  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: "When a user opens a pdf file in the chrome pdf-viewer, and the pdf file
  has a link \nto a url, they can open this link in a new tab. This allows for the
  scheme restrictions\nof a pdf to be bypassed.  This is prohibited in HTML. This
  also should not even be\npossible in a pdf file.\n"
unit_tested:
  fix: true
  code: true
  answer: "The original code was unit tested, it just seems that they somehow completely
    \noverlooked permissions enforcing.  The fix added unit tests that checked origin,\nscheme,
    and link permissions.\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 did not see any major events, the history of this vulnerability was important,
    but short.  Just a general oversight of a case that should have never been allowed
    in a pdf.
  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: 
  commits:
  - note: This commit split a class into base and Chrome implementations. This redeligation
      of responsibilities is probably where the root/cause of the bug was created,
      if this wasn't where the bug itself was introduced.
    commit: 1ce1597337ec9459598cc84a6bc3831c2ea3dfac
  - note: This commit took out a big chunk of code and it is the second time this
      commit was made, as the first one was reverted for causing a bug. The commit
      in general smells and I can see issues being raised here.
    commit: 6ae04a013f6040f5d38e6cf04f6da224f21b77f9
  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.