CVE-2014-8547

aka TallGIF Overflow

CVE: CVE-2014-8547
CWE: 120
ipc:
  note: While the GIF is likely to be received over IPC, IPC is not responsible for
    the vulnerability
  answer: false
  question: |
    Did the feature that this vulnerability affected use inter-process
    communication? IPC includes OS signals, pipes, stdin/stdout, message
    passing, and clipboard. Writing to files that another program in this
    software system reads is another form of IPC.

    Answer should be boolean.
CVSS: AV:N/AC:L/Au:N/C:P/I:P/A:P
bugs: []
i18n:
  note: Errors in calculating the height of the GIF should not be affected by internationalization
  answer: false
  question: |
    Was the feature impacted by this vulnerability about internationalization
    (i18n)? An internationalization feature is one that enables people from all
    over the world to use the system. This includes translations, locales,
    typography, unicode, or various other features.

    Answer should be boolean. Write a note about how you came to the conclusions
    you did.
vccs:
- note: Identified by SZZUnleashed
  commit: 06d392a7cc93dcab84c225d7e8cb7030d537581f
fixes:
- note: 'The people who fixed this vulnerability has also fixed a lot of other similar
    out-of-bounds vulnerabilities

    '
  commit: 8f1457864be8fb9653643519dea1c6492f1dde57
bounty:
  amt: 
  url: 
  announced: 
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: A GIF has to be crafted in order to exploit the vulnerability
    applies: true
  distrust_input:
    note: A GIF could be sent to cause arbitrary code execution or denial of service
    applies: true
  least_privilege:
    note: The GIF decoder could be sandboxed to prevent it from accessing all of the
      resources in the system to prevent a denial of service attack.
    applies: true
  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: 
upvotes: 2
CWE_note: 
lifetime:
  answer: 'During the lifetime of the vulnerability, most of the commits were about
    adding new features to the GIF decoder. Some of those features included adding
    support for transparent pixels, adding checks for edge cases, and fixing issues
    with memory allocation (such as checking if the pointer is in a valid location).
    Many developers worked on the file during the lifetime of the vulnerability, but
    one developer worked on the file for half a year before any other developers worked
    on the file. There was also a switch to refcounted AVframes, which is an API introduced
    in an updated version of a library they are using, as well as porting to the bytestream2
    API. Also, near the end of the lifetime, a series of commits focused around fixing
    out of bounds vulnerabilities were pushed by the same developer that patched this
    vulnerability.

    '
  question: |
    We consider the "lifetime" of this vulnerability to be from the earliest
    VCC to the latest fix.

    How would you characterize the development of this vulnerable code during
    its lifetime? Many new features? Neglected? One developer?
    Massive refactoring? Changing big dependencies?
    Changing architectures or language?


    What about the time period for the project itself?
    Did it undergo big changes during this time?

    Look at:
      * the commit messages between the two, using a command like
          git log --stat abc..def -- your/file.c
          (where a)
      * the changelog between the two
mistakes:
  answer: "A lack of understanding seems to have resulted in this vulnerability as
    the issue seemed to be caused by \ndevelopers not knowing how to properly calculate
    the height of the GIF. The lack of comments in the function may have \ncontributed
    to the vulnerability remaining for this long, as developers would have to spend
    more time to review \nand understand the code. While the commit message says the
    vulnerability was fixed, the function is poorly \ndocumented, and does not provide
    any reason why this fix patches the vulnerability.\n"
  question: |
    In your opinion, after all of this research, what mistakes were made that
    led to this vulnerability? Design mistakes? Maintainability? Requirements?
    Miscommunications? Lack of testing? Lack of understanding? Lack of
    specifications? Working alone?

    An answer like "it was just a coding mistake" is not thoughtful enough.
    If it's such an easy mistake to make, how was it missed?

    Also, 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.
nickname: TallGIF Overflow
subsystem:
  name: avcodec
  answer: The vulnerability was fixed by fixing a file in the avodec directory
  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.

    In FFmpeg, the Component field is useful here. Often people will say
      "undetermined" - do more homework than them and make a judgement call if
      you can.

    Note: a filepath is NOT a subsystem - that's too granular.

    A non-exhaustive examples for ffmpeg are:
      * avcodec
      * avdevice
      * avfilter
      * avformat
      * avutil
      * build system
      * documentation
      * fate
      * ffplay
      * ffprobe
      * postproc
      * swresample
      * swscale
      * tools
      * trac
      * website

    If this involves fixing multiple subsystems, you can make this an array.

    In 'answer', explain how you arrived at this determination.
discovered:
  answer: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
  contest: false
  question: |
    How was this vulnerability discovered?

    Find any relevant bug reports or mailing list conversations read the
    conversation to find out how this was
    originally found. Answer in longform below in "answer".

    If it's clear that the vulenrability was discovered by a
    contest, fill in the name of the contest in "answer".

    If it's clear that it was found by a developer of the project itself,
    e.g. from the email address or a previous committer.

    The automated, contest, and developer flags can be true, false, or nil.

    If there is no evidence as to how this vulnerability was found, then please
    explain where you looked. Thus, 'answer' should always have some
    explanation.
  automated: false
  developer: true
description: "When gifdec.c is reading a GIF, the height of an image may not be properly
  computed. This allows a crafted GIF to \nallow an attacker to write code outside
  of the allocated space. This results in an out-of-bounds access, allowing \nattackers
  to make the system crash, and possibly make execute arbitrary code.\n"
unit_tested:
  fix: false
  code: false
  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 code: and fix: - your answer should be boolean.

    For the code_answer below, look not only at the fix but the surrounding
    code near the fix in related directories and determine if and was there were
    unit tests involved for this subsystem. The code

    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.

    In FFmpeg, they have the FATE suite of regression tests. They are not
    "unit" tests per se, but are automated regression tests. If the fix for the
    vulnerability involved adding or updating a FATE suite, then make fix: true.
  fix_answer: There were no unit tests introduced when the vulnerability was fixed.
  code_answer: There do not appear to be any unit tests related to testing the function
    the vulnerability occurs in.
reported_date: 
specification:
  answer: false
  answer_note: None of the artifacts listed above mention this vulnerability violatiing
    a specification
  instructions: |
    Is there mention of a violation of a specification? For example,
    an RFC specification, a protocol specification, codec spec, or a requirements
    specification.

    Be sure to check all artifacts for this: bug report, security
    advisory, commit message, etc.

    The answer field should be boolean. In answer_note, please explain
    why you come to that conclusion.
announced_date: 2014-11-05T11:55Z
curation_level: 1.0
published_date: 2014-11-05T11:55Z
CWE_instructions: |
  Please go to http://cwe.mitre.org and find the most specific, appropriate CWE
  entry that describes your vulnerability. We recommend going to
  https://cwe.mitre.org/data/definitions/699.html for the Software Development
  view of the vulnerabilities. We also recommend the tool
  http://www.cwevis.org/viz to help see how the classifications work.

  If you have anything to note about why you classified it this way, write
  something in CWE_note. This field is optional.

  Just the number here is fine. No need for name or CWE prefix. If more than one
  apply here, then choose the best one and mention the others in CWE_note.
autodiscoverable:
  answer: true
  answer_note: Most likely, as this is a buffer overflow where an improper value was
    added to a pointer.
  instructions: |
    Is it plausible that a fully automated tool could have discovered
    this? These are tools that require little knowledge of the domain,
     e.g. automatic static analysis, compiler warnings, fuzzers.

    Examples for true answers: SQL injection, XSS, buffer overflow,
    use-after-free

    Examples for false: specification violations, permissions issues, anything
    that would require a tool to be "aware" of the project's
    domain-specific requirements.

    The answer field should be boolean. In answer_note, please explain
    why you come to that conclusion.
bugs_instructions: |
  Are there any bug reports that trace to this vulnerability?

  Sometimes a commit message will mention a bug, or the security page on FFmpeg.
  Sometimes you need to search bug database, which is here:
      https://trac.ffmpeg.org
yaml_instructions: |
  ===YAML Primer===
  This is a dictionary data structure, akin to JSON.
  Everything before a colon is a key, and the values here are usually strings

  For one-line strings, you can just use quotes after the colon

  For multi-line strings, as we do for our instructions, you put a | and then
  indent by two spaces.

  For readability, we hard-wrap multi-line strings at 80 characters. This is
  not absolutely required, but appreciated.
  === End YAML Primer===
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:
  commits:
  - note: "This commit ports the GIF decoder to use a new API that involves changing
      code that reads the colors and \ndimensions of the GIF, but does not touch the
      code that caused the vulnerability.\n"
    commit: 3fd60d804996031ceaba9cad0b38652b92551eb0
  question: |
    Optional: 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?

    This is a catch-all for any interesting commit you find.
    Example of interesting commits:
      * Giant refactors
      * Changing an API or big dependency
      * A change that looks really sketchy
      * Commits where a developer mentions security in their message or comments
curated_instructions: |
  If you are manually editing this file, then you are "curating" it.
  This will enable additional integrity checks on this file to make sure you
  fill everything out properly.

  IMPORTANT: If you are a student, we cannot accept your work as finished unless
  curation_level is properly set.

  The latest curation level is 1.0.
  If you are curating this vulnerability, set it to the latest curation level.
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.
nickname_instructions: |
  A catchy name for this vulnerability that would draw attention it. If the
  report mentions a nickname, e.g. "Heartbleed", use that. Or come up with one!

  Must be under 30 characters. Optional. Be appropriate.
reported_instructions: |
  What date was the vulnerability reported to the security team? Look at the
  security bulletins, bug reports, commit messages of the fix.

  Reported date is likely the same as announced and published. Leave blank if
  you can't find it out.

  Please enter your date in YYYY-MM-DD format.
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 of this for FFmpeg are their version numbers traced to tags:

    https://ffmpeg.org/security.html
    https://github.com/FFmpeg/FFmpeg/releases


  Please enter your date in YYYY-MM-DD format.
fixes_vcc_instructions: |
  Please put the commit hash in "commit" field below (see my example in
  CVE-2011-3092.yml).

  Fixes and VCCs follow the same format - they are arrays of hashes.

  The notes field is optional - place anything that clarifies things or you
  find interesting in there.
published_instructions: |
  Is there a published fix or patch date for this vulnerability?
  Please enter your date in YYYY-MM-DD 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 project-specific
  stuff. Remove references to versions, specific filenames, and other jargon
  that outsiders to this project would not understand. Technology like "regular
  expressions" is fine, and security phrases like "invalid write" are fine to
  keep too.

  Your target audience is people just like you before you took any course in
  security