CVE-2017-7675

aka Tomcat URL Traversal

CVE: CVE-2017-7675
CWE: 22
bugs: []
vccs:
- note: "Used git blame to find the first occurrence of the code causing the\nvulnerability.
    A handful of commits exist betweeen this one and the fix,\nso there have been
    regular updates over the 4 years since the VCC. \n"
  commit: 027d69fc46d31de5d5252c2724f658a4c373b14c
fixes:
- note: SVN rev 1796090, from the Tomcat website.
  commit: cf181edc9a8c239cde704cffc3c503425bdcae2b
- note: SVN rev 1796091, from the Tomcat website.
  commit: dacb030b85fe0e0b3da87469e23d0f31252fdede
- note: 
  commit: 
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: "The vulnerability was caused by user-controlled input not being \nproperly
      parsed by the server when interpreting an HTTP request. \n"
    applies: true
  least_privilege:
    note: 
    applies: 
  native_wrappers:
    note: 
    applies: 
  defense_in_depth:
    note: "Perhaps this shouldn't be the only spot where we're able to prevent\ntraversal
      based vulnerabilities? While we may need different functions\nor cases to parse
      parameter strings, perhaps we can apply a blanket\nvalidation after any of those
      cases are considered! This is also\na good reason for looking into proper permissions
      (maybe sandboxes)\nwhen devs go to host servers using this technology. \n"
    applies: true
  secure_by_default:
    note: 
    applies: 
  environment_variables:
    note: 
    applies: 
  security_by_obscurity:
    note: 
    applies: 
  frameworks_are_optional:
    note: 
    applies: 
upvotes: 5
mistakes:
  answer: "Based on the comments surrounding the original implementation, as well
    as\nthe brief history of commits revolving around the chunk of code containing\nthe
    vulnerability and the lack of targeted unit tests; this vulnerability\nwas most
    certainly caused by a lack of proper risk assessment. \n\nWith a comment like
    \"This is almost certainly wrong and needs to be decoded\",\nit seems like this
    part of the code didn't receive the proper amount of\nattention to determine that
    it may lead to some vulnerabilities if not\nproperly tested. \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: Tomcat URL Traversal
reported: 
announced: '2017-05-24'
subsystem:
  name: http2
  answer: "Based on the directory structure, the commit message and the\noriginal
    bug report, the vulnerability exists in the http2 module. \n"
  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: '2017-05-24'
  answer: "The vulnerability was discovered by Markus Dörschmidt. His original\nreport
    can be found here; https://bz.apache.org/bugzilla/show_bug.cgi?id=61120\n\nThe
    vulnerability was noticed without a full understanding of the implications\nof
    the vulnerability. Markus discovered that using the HTTP/2 module would cause\nsome
    request parameters to disappear (\"all URL path parameters\"). \n"
  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
    * If it's clear that the vulnerability was discovered by a contest,
      fill in the name there.
    * The "automated" 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", BUT please write down
    where you looked in "answer".
  automated: false
description: "This vulnerability involves the processing of an HTTP request\nwhere
  one of the path parameters is a URL with the ability to traverse outside\nof the
  folder where the module is pointing, depending on the URL string that\nthe user
  passes to the server.\n\nThis ultimately happens because, for that particular parameter
  (and maybe\nothers) a number of existing security checks were skipped over in the\nimplementation.
  \n"
unit_tested:
  fix: true
  code: false
  answer: "It does not appear that the original case was unit tested, because\nan
    entirely new test class (TestStream.java) was added to the system. Looking\nat
    other unit tests in the same directory, there don't appear to be any unit\ntests
    that caught the case where the session ID was changed (an indication \nof the
    root issue). \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?
    Write the reasoning behind your answer in the "answer" field.
    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. Must be just "true" or "false".
    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.
    Must be just "true" or "false".
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!)
incomplete_fixes:
- note: 
  commit: 
- note: 
  commit: 
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: "This commit was merged in a month before the bug was reported and \nadjusts
      the chunk of code that caused the vulnerability. However, it\nmerely adjusted
      the indenting of the chunk and the structure of some of \nthe surrounding logic.\n\nOf
      more interest is the commit message! \":path header must not be empty\".\nThis
      seems to imply that signs of the vulnerability were noticed elsewhere,\nbut
      the true cause of the issue waas not fully understood at the time.\n\nThere
      are a few commits in between here and the original VCC.\n"
    commit: 0e98a962b28a4d5a042b02df53b9b0e00337889c
  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: |
  Students: when initially writing this, ignore this upvotes number.
  Once this work is being reviewed, 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: |
  Nickname is optional. Provide a useful, professional, and catchy nickname for
  this vulnerability. Ideally fewer than 30 characters. This will be shown
  alongside its CVE to make it more easily distinguished from the rest.
reported_instructions: |
  Was there a date that this vulnerability was reported to the team? You can
  find this in changelogs, blogs, bug reports, or perhaps the CVE data.
  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 data.
  Please enter your date in YYYY-MM-DD format.
fixes_vcc_instructions: |
  Please put the Git commit SHA in "commit" below, and any notes about how this
  was discovered in the "note" field.
  Refer to our instructions on how to find a Git SHA from an SVN revision.
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.
incomplete_fix_instructions: |
  Did the above "fixes" actually fix the vulnerability?
  Please list any fix commits for this vulnerability that had to be corrected
  at a later date.