CVE-2015-6781

CVE: CVE-2015-6781
CWE:
- 190
- 189
bugs:
- 497302
repo: 
vccs:
- note: |
    Introduced from using a third party library. So the commit hash is
    unobtainable.
  commit: 
fixes:
- note: Fix the win64 GN build after r351207.
  commit: d02508f8c010b1415f5f1521a6f4cee260d1f8a9
- note: Pull sfntly from GitHub instead of code.google.com. Pick up latest release.
    Adjust build files. Update README.chromium SFNTly is a third party library that
    allows the use of SFNT, a font file format. It stands for scalable font.
  commit: 3e7d8e08a0fd550e03c5d83621871bd36803e727
bounty:
  date: '2015-12-01 14:43:00.000000000 -05:00'
  amount: 1000.0
  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: |
      Font files have many variables such as weight, slope, width,
      optical size, metrics and serifs. All of these variables can potentially
      exposed to integer overflow vulnerability if not properly handled. Due to
      complex nature of file formats, it is difficult to conceive all possible
      valid inputs.
    applies: true
  distrust_input:
    note: 
    applies: 
  foreign_library:
    note: |
      Depending on another library introduces all the vulnerabilities that exist
      into the program.
    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:
- 1373143002
- 1367323002
upvotes: 7
mistakes:
  answer: |
    Looking at the issue report it seemed that it stemmed from a coding mistake
    since part of the fix was to make sure that the value in question does not
    wrap around when it reaches the maximum integer. When getting the
    vulnerability fixed, there was a lot of miscommunications on which team
    is responsible for fixing the mistake, which led to the vulnerability to
    exist longer than it needed to.
  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 20:59:18.633000000 -05:00'
subsystem:
  name: sfntly
  answer: |
    Vulnerability found the SFNTLY subsystem. Inside was an adjustable
    variable that was set to INTMAX.
  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: '2015-06-05'
  answer: |
    This vulnerability was discovered by someone's Fuzzer. It caused a crash
    due to incrementing a number that was related to font data.
  google: false
  contest: miaubiz
  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: |
  Integer Overflow that allows remote attacker to cause denial of service or
  possibly have unspecified other impact via modified values in font data.
unit_tested:
  fix: false
  code: false
  answer: |
    Unit tests were not involved in discovering this vulnerability.
    This code is unit tested but by the STNT library so they are outside of the
    repo.
  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: |
    One of the key member of the SFNT team left and was unavaible to help fix
    this vulnerability. Also, there was miscommunication on whose team should be
    responsible for fixing this.
  events:
  - date: '2015-09-18'
    name: Miscommunications
  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: |
    None but the commit that solved this vulnerability did so in part by
    changing how the SFNT library is compiled and built. It included changing
    the location of where source files were.
  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.