CVE-2014-3198

CVE: CVE-2014-3198
CWE:
- 119
bugs:
- 415307
repo: 
vccs:
- note: This VCC was large and added a lot of functionality.  This is where the call
    for the index was introduced without checking if it would be -1.
  commit: 1b1e9effe9fa3b66dd1bcfff4b78455460f66c61
fixes:
- note: The fix was checking if the index was set to -1
  commit: 9b04ffd8e7a07e9b2947fe5b71acf85dff38a63f
bounty:
  date: '2014-10-07 16:12:00.000000000 -04:00'
  amount: 1500.0
  references:
  - http://chromereleases.googleblog.com/2014/10/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: they did not consider the cases where there may be no visible page. Because
      they overlooked this scenario they did not check to make sure the index returned
      was not -1.
    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:
- 601343002
- 560133004
upvotes: 
mistakes:
  answer: |-
    The vulnerability was caused by simply overlooking the case where there is no visible page and -1 is returned, which causes the logic to try and index by -1.  Once the fuzzer found the issue it was a very simple fix.
    Interestingly this case of returning -1 when there is no visible page was checked for further down in the file. In the entire file they checked for the first visible page 3 times.  The first 2 occasions they did not check to see if -1 was returned, but the third time they did. Due to the fact the the VCC added a lot of functionality this leads me to beleive that they did not thouroughly check the commit and only happened to consider this edge case in the third scenario.  Because there was no unit testing they did not notice this simple mistake until the fuzzer found it and then they were able to add in the checks for -1.
  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: '2014-10-08 06:55:06.737000000 -04:00'
subsystem:
  name: PDFium
  answer: Based on the description in the CVE
  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: '2014-09-17'
  answer: The vulnerability was found by ClusterFuzz causing a heap buffer overflow.
    They could not reproduce locally, but they were confident they knew what the issue
    was, so they created a speculative fix.  After the fix was added ClusterFuzz detected
    the error as fixed.
  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: true
description: When scrolling using the arrow keys the subsystem PDFium does a check
  for the first visible page.  In the case where there is not yet a visible page this
  check will return -1.  There was no check for this scenario which caused an attempt
  to index by -1 resulting in a buffer overflow. The app would then crash causing
  a denial of service. The buffer overflow also exposes the app to potential data
  corruption or malicious code execution.
unit_tested:
  fix: false
  code: false
  answer: The fix did not invlove automated tests.  The bug was found with a fuzzer
    and the fix was tested against the fuzzer.  There does not appear to be any unittesting
    for the subsytem PDFium, only test cases in ClusterFuzz.
  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: 
    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: 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: There were no interesting commits.  The only other commit was 2 days prior
      to this vulnerability being fixed and was unrelated.
    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.