CVE-2017-7668

CVE: CVE-2017-7668
CWE: 20
ipc:
  note: 
  answer: 
  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. Explain your answer
bugs: []
i18n:
  note: 
  answer: 
  instructions: |
    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.
repo: 
vccs:
- note: |-
    SVN revision 83750. This is the initial commit for the ap_find_token()

    function.


    Formerly 5430f8800f5fffd57e7421dee0ac9de8ca4f9573 before HTTPD rewrote Git history.
  commit: 6f96ad52275b5b35226cdb2ce66b3832e9dfb605
- note: 
  commit: 
fixes:
- note: Formerly ad581ced12363ce82ffcb16133f236b2e31563e1 before HTTPD rewrote Git
    history.
  commit: edb6db90d2474b5807b2459b3380bf947c5866fa
- note: Formerly a585e36e06a53170be6d2d462ceb5b30b8382988 before HTTPD rewrote Git
    history.
  commit: b2445f6e1bfa79c28bfab45e924c95fe350bf67f
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: 
    applies: 
  distrust_input:
    note: In this case, the input was trusted to not have extra NUL characters.
    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: []
upvotes: 3
CWE_note: 
mistakes:
  answer: |
    A concious, documented decision was made to not check for NUL characters
    when searching for the start of a token in the input string. When working
    in C, where string parsing is a ripe target for buffer overruns, this
    should have raised some alarms.
    Normal HTTP headers should never contain NUL characters, so when one shows
    up somewhere it isn't expected, the server should treat it as a malformed
    request and stop attempting to process it normally. Workarounds should not
    be implemented in case a NUL character is encountered in the middle of a
    string, because that's not something that should be happening in the first
    place. Additionally, for software as widespread as Apache HTTPD,
    implementing non-standard behavior only encourages nonconformity to the
    established standards.
  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.
nickname: 
reported: 
announced: '2017-06-19'
published: 
subsystem:
  name: HTTP Token parsing
  answer: Based on the use of the target function.
  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.
discovered:
  date: '2017-05-06'
  answer: |
    Discovered using American Fuzzy Lop. The reporter describes their fuzzing
    method in a blog post found here (https://sensepost.com/blog/2017/fuzzing-apache-httpd-server-with-american-fuzzy-lop-%2B-persistent-mode/).
  google: false
  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 this part blank.
  automated: true
description: |
  When parsing HTTP request headers, the ap_find_token() function in the Apache
  HTTPD server would overrun the string buffer when searching for a specific
  token. If line being searched contained a NUL (\0) character in the last
  token of the string, then the function would continue to read past the end of
  the string resulting in a buffer overrun.
  This occurs because of how the ap_find_token() function searched for the
  beginning of a token. If a NUL character was found, the function would skip
  past it and continue processing the memory beyond the NUL character.
unit_tested:
  fix: true
  code: true
  answer: |
    There were existing unit tests for this code prior to the fix. After the
    fix was implemented, an additional case in the unit tests was added for the
    vulnerability.
  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.
specification:
  answer: 
  answer_note: 
  instructions: |
    Is there mention of a violation of a specification? For example,
    an RFC specification, a protocol specification, 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.
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!)
autodiscoverable:
  answer: 
  answer_note: 
  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

    Examples for false: RFC violations, permissions issues, anything
    that requires the 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.
yaml_instructions: 
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: |
    After the initial commit of the code, the only change to the function were
    some style changes to keep line lengths under 80 characters. There was no
    real code change between the initial commit and the fix commit.
  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?
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.
nickname_instructions: |
  A catchy name for this vulnerability that would draw attention it. If the
  report mentions a nickname, use that. Must be under 30 characters.
  Optional.
reported_instructions: |
  What date was the vulnerability reported to the security team? Look at the
  security bulletins and bug reports. It is not necessarily the same day that the
  CVE was created.  Leave blank if no date is given.
  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 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.
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 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.