CVE-2014-3730

aka URL Is Not Safe

CVE: CVE-2014-3730
CWE: 20
ipc:
  note: The affected subsystem could send http messages, however that is not inter-process.
  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:M/Au:N/C:N/I:P/A:N
bugs: []
i18n:
  note: It had nothing to do with internationalization, it has to do with a lack of
    sanitization in URLs.
  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.
repo: https://github.com/django/django/
vccs:
- note: Fixed logout view to use the 'next' GET parameter correctly as described in
    the docs, while only allowing redirection to the same host. 13-2-2011
  commit: 751888ece3c970e208d9d77f21a35464c9122835
- note: Tightened the security check for "next" redirects after login. 3-1-2010
  commit: 6e748b5db4ea6db78ce389f474c2fb78ee3976ed
- note: Auth.views.login now allows for login redirections for different schemes with
    the same host (or no host even, e.g. 'https:///login/'). 11-27-2010
  commit: e74edb4d53b089ec57ec4830eeba98607283a092
- note: Fixed is_safe_url() to reject URLs that use a scheme other than HTTP/S. 8-13-2013
  commit: ec67af0bd609c412b76eaa4cc89968a2a8e5ad6a
- note: Ensured that redirects can't be poisoned by malicious users. 11-17-2012
  commit: b2ae0a63aeec741f1e51bac9a95a27fd635f9652
- note: Input validation and tests for base36 conversion utils. 2-15-2012
  commit: 6072e108e2738dbde7c2ad976a45745551859a20
- note: Fixed is_safe_url() to reject URLs that use a scheme other than HTTP/S. 8-13-2013
  commit: 1a274ccd6bc1afbdac80344c9b6e5810c1162b5f
- note: Ensured that redirects can't be poisoned by malicious users. 11-17-2012
  commit: fce1fa0f7fb984d4e76eb81ffc3cb9826046c3b5
- note: Fixed parse_http_date docstring and moved related tests. Unrelated.
  commit: b3ee80a0cf0e60876f03b797d2bdc69505dbdfcb
- note: Fixed is_safe_url() to reject URLs that use a scheme other than HTTP/S. 8-13-2013
  commit: 79594b40c087c19fecc72af042c835b11a519b78
- note: Unrelated to vulnerability.
  commit: 4f4e9243e4cf585e32a882804084853108ef94c0
- note: Ensured that redirects can't be poisoned by malicious users. This is where
    the vulnerability is created. 11-17-2012
  commit: a2f2a399566dd68ce7e312fff5a5ba857066797d
- note: Fixes is_safe_url() to reject URLs that use a scheme other than HTTP/S. 8-13-2013
  commit: ae3535169af804352517b7fea94a42a1c9c4b762
fixes:
- note: Added additional checks in is_safe_url to account for flexible parsing. 5-12-2014
  commit: 7feb54bbae3f637ab3c4dd4831d4385964f574df
- note: Added additional checks in is_safe_url to account for flexible parsing. 5-12-2014
  commit: ad32c218850ad40972dcef57beb460f8c979dd6d
- note: Added additional checks in is_safe_url to account for flexible parsing. 5-12-2014
  commit: 601107524523bca02376a0ddc1a06c6fdb8f22f3
- note: Added additional checks in is_safe_url to account for flexible parsing. 5-12-2014
  commit: e7b0cace455c2da24492660636bfd48c45a19cdf
bounty:
  amt: 
  url: 
  announced: 
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: |
      The vulnerability can be exploited by sending in an input that wasn't validated.
      The developer should have accounted for more than just the two cases they initially validated for.
    applies: true
  least_privilege:
    note: 
    applies: false
  native_wrappers:
    note: 
    applies: false
  defense_in_depth:
    note: 
    applies: false
  secure_by_default:
    note: 
    applies: false
  environment_variables:
    note: 
    applies: false
  security_by_obscurity:
    note: 
    applies: false
  frameworks_are_optional:
    note: 
    applies: false
reviews: []
sandbox: 
upvotes: 7
CWE_note: "The vulnerability can be classified as CWE-20 because \nthe function is_safe_url
  does not validate or incorrectly validates input that can affect the control flow
  or data flow of the program.\n"
mistakes:
  answer: "This vulnerability was brought on by carelessness, the author of the is_safe_url
    function wrote it out of neccesity without putting \nany real thought into the
    consequences of the function. The first mistake the original author made was not
    writing unit tests for the function.\nIf unit tests were implemented I feel as
    though the author may have thought of additional cases to test and in doing so
    found the vulnerability the\nfunction was open to. Additionally if unit tests
    had been in place for the function, then different developers down the line would
    have been forced\nto write their own tests for the function and in doing so may
    have also discovered the vulnerability. One interesting note is that it appears
    a second\nvulnerability was found in this function as well, and that fix still
    did not result in unit tests, which was a mistep to be sure. If there had been
    a \nrequirement for unit testing alongside a more thoughtful design from the original
    author, this vulnerability would have never became an issue. \nThe lesson to be
    learned here is that even a simple function like a validation check can open you
    to many different forms of attack, and should be \nconsidered when you are designing
    any piece of software large or small.\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.
nickname: URL Is Not Safe
subsystem:
  name: http
  answer: The vulnerability was located in a http utility function whose responsibilities
    lie in performing http related actions, therefore it is the http subsystem.
  question: |
    What subsystems was the mistake in?

    Most systems don't have a formal list of their subsystems, but you can
    usually infer them from path names, bug report tags, or other key words
    used. A single source file is not what we mean by a subsystem. In Django,
    the "Component" field on the bug report is useful. But there may be other
    subsystems involved.

    Your subsystem name(s) should not have any dots or slashes in them. Only
    alphanumerics, whitespace, _, - and @.Feel free to add multiple using a YAML
    array.

    In the answer field, explain where you saw these words.
    In the name field, a subsystem name (or an array of names)

    e.g. clipboard, model, view, controller, mod_dav, ui, authentication
discovered:
  answer: Peter Kuma and Gavin Wahl reported the issue to Django.
  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, 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.
  automated: false
  developer: false
description: "A critical vulnerability that can be initiated remotely and with no\nform
  of authentication required for a successful exploitation, was found in Django. \nPeter
  Kuma and Gavin Wahl found that the django.util.http.is_safe_url function does not
  properly validate URLs, \nwhich allows remote attackers to conduct open redirect
  attacks via a malformed URL, \nas demonstrated by \"http:\\\\\\djangoproject.com.\"\n"
unit_tested:
  fix: true
  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.
  fix_answer: New test cases were added for the corresponding fix, see 7feb54bbae3f637ab3c4dd4831d4385964f574df.
  code_answer: There were unit tests but not for the method the vulnerability existed
    in, see a2f2a399566dd68ce7e312fff5a5ba857066797d.
discoverable: 
reported_date: 
specification:
  answer: false
  answer_note: There was no mention of a specification being followed.
  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.
announced_date: 2014-05-16T15:55Z
curation_level: 1
published_date: '2014-05-16'
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.
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.
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 is interesting because this is where the vulnerability is introduced.
      \nIt appears that the author just wanted to implement a simple validation function
      for the URL and did not think of every consideration, and\nin doing so introduced
      a vulnerability. Additionally it can be seen that no unit tests were implemented
      with this initial commit. If the author\nhad implemented unit tests for this
      method, would the vulnerability have existed?\n"
    commit: a2f2a399566dd68ce7e312fff5a5ba857066797d
  - note: |
      This commit is interesting because it was about fixing a different vulnerability having to do with rejecting incorrect schemes,
      and unit tests still were not implemented for the function. The developers of this function were able to find a different vulnerability but
      did not take the time to think about how else the function might be vulnerable, and did not unit test either.
    commit: 1a274ccd6bc1afbdac80344c9b6e5810c1162b5f
  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 version number that you were given in your instructions.

  This will enable additional editorial 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 properly updated.
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 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