CVE-2017-9787

aka Spring proxy DoS

CVE: CVE-2017-9787
CWE: 284
bugs: []
vccs:
- note: Code was only added in the fix (not deleted or changed), so the lack of checking
    fora proxy was probably a problem from the start. I just listed the commit which
    created the SecurityMemberAccess.java file, as that was where the check was needed
    to fix the bug.
  commit: 0c543aef318341ca9bd482e15f1637497b8a4dfd
fixes:
- note: Blocks OGNL access to class members of Spring proxy 2.3.x
  commit: 583da3d5df5aeeded3beadca6305a98c5618e46b
- note: Adds constant to control proxy access 2.3.x
  commit: '086b63735527d4bb0c1dd0d86a7c0374b825ff24'
- note: Ports proxy detection to 2.3.x
  commit: ae5630197980fe431f84eb26523f3b23b71f91bc
- note: Blocks OGNL access to class members of Spring proxy 2.5.x
  commit: 4c386c663cf094a6d40d90c56c5983e14d518c26
- note: Adds constant to control proxy access 2.5.x
  commit: 5d999d6ac145c769191cc2e9a4897a47093f43d8
- note: Adds support for Spring proxies when chaining actions 2.5.x
  commit: 8b862f7cb2eaa6289ec9b36e7dc4a47521fc3bca
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: 
    applies: 
  least_privilege:
    note: 
    applies: 
  native_wrappers:
    note: 
    applies: 
  risk_assessment:
    note: The possibility that the Spring proxy could be used for a DoS attack seems
      like something they totally missed. They even made a whole new file for testing
      proxy access when fixing this bug. While you can't catch every risk, risk of
      a DoS attack is something that should probably come up during development of
      a wep application framework. It's possible that the Spring proxy wasn't in their
      particular "bag of tricks" when they were considering security.
    applies: true
  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: 0
mistakes:
  answer: I believe they just missed what looks like a simple check to prevent proxy
    connections. Rather than a coding mistake, it seems their design totally neglected
    handling proxies differently. You can't catch every vulnerability and this one
    must have slipped through risk assessment. CWE-284 mentions carefully handling
    permissions and trust boundaries, and it seems from this bug that a proxy user
    may need restricted access (or none at all) if DoS attacks are a significant risk.
  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 in the software
    engineering industry would find interesting.
nickname: Spring proxy DoS
reported: 
announced: '2017-07-13'
subsystem:
  name: ognl
  answer: The file that was modified in the fixing commits was in the ognl directory,
    and the fix commits specifically mentioned blocking ognl access.
  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: '2017-08-23'
  answer: I was only able to find the bug reporter, Yasser Zamani, with disclosed
    and published dates. Sources checked below. https://issues.apache.org/jira/projects/WW/issues/WW-5011?filter=allopenissues
    https://snyk.io/vuln/SNYK-JAVA-ORGAPACHESTRUTS-31500 https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-9787,
    https://nvd.nist.gov/vuln/detail/CVE-2017-9787, https://cwiki.apache.org/confluence/display/WW/S2-049,
    https://www.securityfocus.com/bid/99562/discuss
  apache: true
  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 Apache
    employee (you can tell from their email address). 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.
    The "apache" 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: 
description: A specific type of proxy could be used to make many connections and launch
  denial of service attacks on Struts.
unit_tested:
  fix: true
  code: true
  answer: There were already unit tests in place for SecurityMemberAccess but none
    involving proxy functionality. When the fix was committed, a new file called SecurityMemberAccessProxyTest.java
    was added so that proxy focused tests would also be included.
  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".
future_fixes:
- note: Commit message says it improves "performance and bug safety" for the previous
    commits. It affects code added in the "Blocks OGNL acess..." commits listed under
    fixes and was not ported back to the 2.3.x version.
  commit: 7987c38d5a65700501eddd1fb0cb1a288921ecd2
curation_level: 1
previous_fixes:
- note: 
  commit: 
- note: 
  commit: 
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!)
security_bulletin: S2-049
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: Since the creation of the SecurityMemberAccess file nothing relating to
    the vulnerability showed up in the commits, which makes sense as it was probably
    off the developers' radar. A feature for passing parameters was added and quickly
    reverted, breaking at least one person's workflow. The SecurityMemberAccess class
    was added to a list of excluded classes and had multiple commits related to this
    (i.e. logging, excluding of whole packages, warning of excluded classes). A function
    was added to check for access to an enum as well as static methods. Another warning
    was added if using the default package, context was added to the deprecation warning,
    and package name checking was changed from pattern matching to using start with
    to improve performance. Then the first fix commit was pushed (583da3d5df5aeeded3beadca6305a98c5618e46b).
  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?
    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 SVN commit number in "commit" below, and any notes about how this
  was discovered in the "note" field.
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 Struts-specific
  stuff. Remove references to versions, specific filenames, and other jargon
  that outsiders to Struts 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 fixes for the same issue before and after
  this CVE below.