CVE-2016-1706

CVE: CVE-2016-1706
CWE:
- 20
bugs:
- 610600
repo: 
vccs:
- note: Also bad22afa2d2ba6349dc0117540d3cf16ed14efa9
  commit: 270d42206f2ff5fc97114c72f2d2cd7c0f4436da
fixes:
- note: |
    Multiple checks were added to ensure BrowserOperations messages originated from browser.
    This verifies that BrowserOperations messages are sent from the trusted browser UI source
    and ignores them if they originate from the renderer.
  commit: 92cad45212731b59e74c8f2a2913691db3e9d770
bounty:
  date: '2016-07-20 14:48:00.000000000 -04:00'
  amount: 15000.0
  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: "Only one of the two expected message inputs was treated as 'untrusted'.
      \ \nDistrust of both message types could have mitigated the vulnerability despite\nthe
      Flash renderer's ability to send BrowserOperations messages.\n"
    applies: true
  least_privilege:
    note: |
      The idea of least privilege applies with this vulnerability. The problem
      was introduced because the channel the browser uses was being published
      in a way that could be read by outsiders. The fix for the vulnerability
      makes it so that this information will never be made viewable. As a
      result, privilege is an important concept here since the original issue
      was that people who were not privileged to view such information were
      still able to view it.
    applies: true
  native_wrappers:
    note: 
    applies: false
  defense_in_depth:
    note: |
      A "defense-in-depth" approach could have mitigated this vulnerability despite
      plugins having unanticipated access to the set of BrowserOperations messages.
      If the design approach had included sanitization for both ConnectToPlugin and
      BrowserOperations message types with the assumption that either could include
      a malicious payload, plugins would still be prevented from unmitigated access.
    applies: true
  secure_by_default:
    note: 
    applies: false
  environment_variables:
    note: 
    applies: false
  security_by_obscurity:
    note: 
    applies: false
  frameworks_are_optional:
    note: 
    applies: false
reviews:
- 2069853002
- 2122313004
upvotes: 3
mistakes:
  answer: "The relevant code appears to have been written by a single developer and
    had not\nbeen modified in almost two years when the vulnerability was found.  The
    presence of\nthis vulnerability appears to be a simple ovesight among largely
    robust code, given \nit lasted so long without requiring modification.  While
    both the original code and\nthe fix do not appear to use unit testing, I believe
    the issue is sufficiently \ncomplex that it would not have been feasible to detect
    it through all but the most \nextensive unit testing.  A 'defense in depth' approach
    would have been useful in this\ncase, which would involve sanitizing and validating
    all received messages from the \nFlash renderer rather than just those expected
    to be vulnerable.\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: '2016-07-20 15:59:01.590000000 -04:00'
subsystem:
  name: renderer_host
  answer: The Flash plugin rendering 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"
discovered:
  date: '2016-05-10'
  answer: "The vulnerability was originally reported from the email 70696e6b...@gmail.com,
    with\nthe user's handle referenced as \"Credit to Pinkie Pie\" next to the vulnerability
    listing\non the stable release update on 2016-07-20.  The reporter used the tool
    \nFrida(http://www.frida.re) for code injection, leading to the discovery of\nthe
    issue.  This user documented their attempts to test potential exploits\nusing
    the vulnerability in a file called \"ppapithing.zip\" included in the initial
    report.\nThe user did not elaborate on other techniques or circumstances leading
    to the issue's discovery.\nInitial report URL: https://bugs.chromium.org/p/chromium/issues/detail?id=610600\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: "This vulnerability resulted from the improper implementation of PPAPI,
  which is\na plugin management API for Adobe Flash Player.  \nPlugins have a broker
  process with two methods for handling messages.\nBrokerProcessDispatcher handles
  BrowserOperations messages managing browser functions\nsuch as locally stored Flash
  cookies and camera/mic permissions.\nBrokerDispatcher handles only ConnectToPlugin
  messages which manage inter-process-communication \ndata for the plugin.\nConnectToPlugin
  messages are treated as untrusted and are sanitized and validated, but BrowserOperations\nmessages
  are not.  BrowserOperations messages are intended for use by the browser's settings\nUI,
  while ConnectToPlugin messages should be sent on behalf plugins.  The Flash renderer
  \nis able to send both types of messages on behalf of plugins, meaning a compromised
  renderer\ncan submit unsanitized data and access powerful BrowserOperations functions.
  The primary danger\nis that several BrowserOperations message variants include an
  absolute file system path\nas an argument with no validation, allowing access to
  local files by the renderer.  An exploit \ncould have the capability to write or
  overwrite local files.  The reporting user described \na potential exploit for OS-X
  where vulnerability is used to mount a remote file system on the\ntarget computer.\n"
unit_tested:
  fix: false
  code: false
  answer: "The VCC did not include any unit tests in either of the relevant commits.
    \ \nNo additional unit tests were introduced as part of the fix.\nThe code review:https://codereview.chromium.org/1322793004\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: |
    It does not appear as though there was much activity with regards to
    development around the affected subsystem. There were many years in between
    commits that touched the files that introduced the vulnerability.
  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: "The vulnerable code was essentially untouched between the VCC and the fix,
    which was \na period of roughly 10 months.\nThough the vulnerability was high
    risk and fixed with only a few lines of code,\nthe lack of development activity
    in an otherwise functional subsystem likely lead\nto this vulnerability's long
    lifespan.  Both git blame and the gitk tool do not show\nchanges to the relevant
    code.\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.