CVE-2013-6656

CVE: CVE-2013-6656
CWE:
- 200
bugs:
- 331725
repo: 
vccs:
- note: 
  commit: 53d2e9d47697451fe615aacfe2ffbe8d3508fe54
fixes:
- note: 
  commit: 64bebe14963d4059d2e5fdba3c8879b83acc39d0
bounty:
  date: '2014-02-20 '
  amount: 500.0
  references:
  - http://chromereleases.googleblog.com/2014/02/stable-channel-update_20.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: "As described in the conversation logs, this XSS vulnerability only happens\nwhen
      a user logs into a site, a redirect (302) was initiated, the attacker \nincluded
      a <script> tag in the url, and a document.write existed on the page \nto access
      the original request body. Programatically parsing urls and pages\nto detect
      a situation like this is very complex.\n"
    applies: true
  distrust_input:
    note: |
      Urls are a form of input and this vulnerability is exploited by XSS
      abuses urls. Distrusting them thru sanitization and blacklisting can somewhat
      mitigate it.
    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: |
      The prerequesites and input needed to make this exploit occur are extremely
      specific and obscure leaving it undetected for a long time. See 'complex_inputs'.
    applies: true
  frameworks_are_optional:
    note: 
    applies: 
reviews:
- 145183002
- 128823003
upvotes: 
Nickname: Young Mind, Old Body
mistakes:
  answer: "I honestly think that this vulnerability came to be because of a typo.
    \n\nThe solution was a one-liner (worth $500) that changed \n\"FormData* httpBody
    = documentLoader->originalRequest().httpBody();\" to\n\"FormData* httpBody = documentLoader->request().httpBody();\"\n\nNotice
    that the only difference is which request function is being used;\neach gives
    the XSS Auditor access to certain http bodies. After a form fill and a login attempt,\nthe
    request http body doesn't contain any of the user's input while the original \nrequest
    body does.\n\nThe vulnerability went long undiscovered mostly because of its security
    by obscurity\ndue to the specificity of its prerequesites and inputs. \n\nSince
    this vulnerability was introduced entirely as new code along with a larger featueset,\nI
    think that the original developer just mistyped and chose the wrong request function\nwhile
    not thinking about the consequences of choosing one or the other. They both \nare
    syntactically similar after all.\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.
announced: '2014-02-20 '
subsystem:
  name: WebKit XSS Auditor
  answer: |
    Based on the CVE title and the file locations. The surrounding directory contains
    C++ files that the core of the browser uses for HTML parsing. It makes sense that
    the XSS Auditor is here because it has the responsibility to read raw HTML content
    and decide if it is an attempting an XSS.
  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: '2014-01-06'
  answer: "The vulnerability was found and fixed by general user neex.emil@gmail.com
    who is a Bug \nBounty Hunter. It doesn't mention it in any of the conversation
    logs, but Neex\nmost likely did some automated XSS to discover this vulnerability
    since it doesn't\noccur often. After, Neex crafted a sandboxed version of the
    exploit and managed to\nconsistently reproduce the XSS problem with the custom
    files.\n"
  google: false
  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" 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: false
description: "The vulnerability was in WebKit's XSS Auditor which is a built-in function
  designed \nto mitigate XSS attacks. It identifies if query parameters contain malicious
  \nJavaScript and block the response if it believes the payloads were injected into
  a response.\n\nXSS Auditor, when processing a POST request with a chain of page
  redirects and a single \nfinal destination page, initializes with the URL of the
  destination page and the body of\nthe initial request page. This means that the
  body of the request page is still accessible \nthru the XSS Auditor by brute-forcing
  character by character the POST body of the initial request.\nHowever, this will
  only occur if the original request url has a <script> tag in it, to make \nXSS Auditor
  suspicious and initialize.\n\nBy pairing this exploit with a login form, an attacker
  can get the body of the form\nwith the user inputs in the values and gain access
  to passwords and other sensitive \ninformation.\n"
unit_tested:
  fix: true
  code: false
  answer: "A set of files were included in the same commit as the file with\nthe fix.
    These files reproduce the exploit in a sandbox and \nmanually test to see if the
    exploit was fixed. Doing a git log and \ngit blame on these files shows that they
    were added to very sparsely \n(about 3 years between commits), and only contained
    more manual tests\nof one-off bugs. No other automated testing was found. \n"
  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: There were no major events during this time.
  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: 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: 
  commits:
  - note: "There were no interesting commits. The log starts off with a big 700+ line
      move of code\nfrom one directory to another. From there pretty much every commit
      is a <20 line change related to small bugs\nin the XSS Auditor. It looks like
      that at this point in time, the XSS Auditor had been long finished and was going
      \nthrough slight maintenance and rigorous public testing.\n"
    commit: 64bebe14963d4059d2e5fdba3c8879b83acc39d0
  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.