CVE-2020-15780

CVE: CVE-2020-15780
CWE:
- 862
ipc:
  note: |
    This bug does not exploit any inter-process communication. Inter-process
    communication is involved, but the exploit itself did not take advantage of
    vulnerabilities in this communication.7000
  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 must be true or false.
    Write a note about how you came to the conclusions you did, regardless of
    what your answer was.
CVSS: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
bugs:
- 1173573
i18n:
  note: |
    This vulnerability was completely independent of internationalization. The issue
    had no relation to translations, locales, etc.
  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 true or false
    Write a note about how you came to the conclusions you did, regardless of
    what your answer was.
vccs:
- note: Discovered automatically by archeogit.
  commit: 0bf54fcd95042bd178cb25368422cf4474fc8492
- note: Discovered automatically by archeogit.
  commit: 772bf1e2878ecfca0d1f332071c83e021dd9cf01
- note: Discovered automatically by archeogit.
  commit: 612bd01fc6e04c3ce9eb59587b4a7e4ebd6aff35
fixes:
- note: 'Manually confirmed

    '
  commit: 75b0cea7bf307f362057cc778efe89af4c615354
vouch:
  note: |
    All of the commit messages had at least one person sign off on them. This commit
    that ultimately solved issue was signed off by two different people, include the
    person who originally found the exploit.
  answer: true
  question: |
    Was there any part of the fix that involved one person vouching for
    another's work?

    This can include:
      * signing off on a commit message
      * mentioning a discussion with a colleague checking the work
      * upvoting a solution on a pull request

    Answer must be true or false.
    Write a note about how you came to the conclusions you did, regardless of what your answer was.
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: 
  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: []
sandbox:
  note: |
    This vulnerability allowed the user to have the ability to perform physical
    address writes. This allowed them to disable lockdown and secure boot, which then
    made it possible to access to sensitive data that otherwise would have been
    inaccessible.
  answer: true
  question: |
    Did this vulnerability violate a sandboxing feature that the system
    provides?

    A sandboxing feature is one that allows files, users, or other features
    limited access. Vulnerabilities that violate sandboxes are usually based on
    access control, checking privileges incorrectly, path traversal, and the
    like.

    Answer should be true or false
    Write a note about how you came to the conclusions you did, regardless of
    what your answer was.
upvotes: 5
CWE_note: 'Manually confirmed

  '
mistakes:
  answer: |
    CVE-2020-15780 is a cautionary tale of something that seems obvious, but is all
    too easy to overlook. You should not be able to turn off security measures while
    having those measures activated. Being able to do this effectively means that they
    don't exist at all, so any bad actor with access to the system can simply disable
    them before carrying about the exploit they are meant to prevent.
    In the case of CVE-2020-15780, there was a way to disable lockdown while having
    the lockdown feature is active. This meant that a bad actor who wanted to do
    something such as modify the kernel image, which lockdown would normally prevent,
    by first disabling lockdown. This effectively made the lockdown status irrelevant.
    The simple solution to these kinds of issues is to check the status of the
    security measure before allowing the user to do something that could override it.
    This is exactly how CVE--2020-15780 was fixed. Role-based access control is the
    common solution to any missing authorization weakness.
    While CVE-2020-15780 was a case of simple problem with a simple solution, these
    kind of forgotten checks can be very difficult to realize. Vulnerabilities, such
    as this one, that are easy to fix and hard to find highlight the importance of
    both manual and automated testing/review of code for security vulnerabilities. In
    the case of authorization exploits that don't require much domain knowledge,
    automated tools, such as fuzzers, excel at highlighting where there are
    weaknesses. In the case where domain specific knowledge is required, that is where
    manual testing and review can uncover these issues.
    CVE-2020-15780 demonstrates the importance of having rigid automated and manual
    testing of code to undercover potential security problems. Even though the
    solution may be simple, finding the problem in the first place is the real
    challenge and failing to do so can have serious consequences to the
    confidentiality and integrity of the system.
  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?

    There can, and usually are, many mistakes behind a vulnerability.

    Remember that mistakes can come in many forms:
    * slip: failing to complete a properly planned step due to inattention
              e.g. wrong key in the ignition
              e.g. using < instead of <=
    * lapse: failing to complete a properly planned step due to memory failure
              e.g. forgetting to put car in reverse before backing up
              e.g. forgetting to check null
    * planning error: error that occurs when the plan is inadequate
              e.g. getting stuck in traffic because you didn't consider the
                   impact of the bridge closing
              e.g. calling the wrong method
              e.g. using a poor design

    These are grey areas, of course. But do your best to analyze the mistakes
    according to this framework.

    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?

    Write a thoughtful entry here that people in the software engineering
    industry would find interesting.
nickname: 
subsystem:
  name:
  - drivers
  note: "The mistakes appears in the ACPI drivers. \n"
  question: |
    What subsystems was the mistake in? These are WITHIN linux kernel

    Determining the subsystem is a subjective task. This is to help us group
     similar vulnerabilities, so choose a subsystem that other vulnerabilities would be in. Y

    Some areas to look for pertinent information:
      - Bug labels
      - Directory names
      - How developers refer to an area of the system in comments,
        commit messages, etc.

    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.

    Example linux kernel subsystems are:
      * drivers
      * crypto
      * fs
      * net
      * lib

    Name should be:
      * all lowercase English letters
      * NOT a specific file
      * can have digits, and _-@/

    Can be multiple subsystems involved, in which case you can make it an array
    e.g.
        name: ["subsystemA", "subsystemB"] # ok
        name: subsystemA # also ok
discovered:
  answer: "This bug was originally discovered by an independent security researcher.
    They \ndiscovered it by following a similar process used to exploit a different\nvulnerability
    (not reference by name). Using these previous known tricks, they \ndiscovered
    that you can inject an ACPI table and suggested the fix of checking \nthe lockdown
    status before allowing a new ACPI table to be installed. \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, 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: true
discussion:
  note: |
    Does not seem like there was any discussion. The person who found the bug
    suggested a solution in their bug report. This solution was ultimately used to
    fix the bug, and it seemed no one offered an alternate solution.
  question: |
    Was there any discussion surrounding this?

    A discussion can include debates, disputes, or polite talk about how to
    resolve uncertainty.

    Example include:
      * Is this out of our scope?
      * Is this a security?
      * How should we fix this?

    Just because you see multiple comments doesn't mean it's a discussion.
    For example:
      * "Fix line 10". "Ok" is not what we call a discussion
      * "Ping" (reminding people)

    Check the bugs reports, pull requests, and mailing lists archives.

    These answers should be boolean.
      discussed_as_security: true or false
      any_discussion: true or false

    Put any links to disagreements you found in the notes section, or any other
    comment you want to make.
  any_discussion: false
  discussed_as_security: false
stacktrace:
  note: |
    I looked for stacktraces in the bug report, and there was nothing. The process
    used to replicate this bug was also not discussed in any detail, which I assume
    is because the process is very similar to process that is already known to the
    security team.
  question: |
    Are there any stacktraces in the bug reports?

    Secondly, if there is a stacktrace, is the fix in the same file that the
    stacktrace points to?

    If there are no stacktraces, then both of these are false - but be sure to
    mention where you checked in the note.

    Answer must be true or false.
    Write a note about how you came to the conclusions you did, regardless of
    what your answer was.
  any_stacktraces: false
  stacktrace_with_fix: false
description: "CVE-2020-15780 allowed for injection of a malicious ACPI table via configfs.\nACPI
  is a form of abstraction that allows the Linux operating system to control\nmachine
  specific hardware. ACPI relies on ACPI tables for configurations. Configfs\nis a
  filesystem-based manager of kernel objects. Using configfs, bad actors were \nable
  to send malicious ACPI tables that allowed them to override Linux secure boot\nand
  bypass lockdown. Secure bott is a verification mechanism that ensures code \nlaunched
  by the computer's firmware is trusted. The lockdown feature is designed to \nprotect
  against unauthorized modification of the kernel memory and prevent access to\nsecurity
  and cryptographic data. Overriding these features could allow a bad actor\nto run
  untrusted, or malicious code, or gain access to sensitive data.  \n"
unit_tested:
  fix: false
  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.

    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: 'No automated unit tests were found in the surrounding directories.

    '
  code_answer: "No automated unit tests were found in the surrounding directories.
    \n"
reported_date: '2020-06-15'
specification:
  note: |
    I was unable to find any references that stated there was a violation of
    specification. The principle issue was related to permissions, not a violation of
    any specs.
  answer: false
  instructions: |
    Is there mention of a violation of a specification? For example, the POSIX
    spec, an RFC spec, a network protocol spec, or some other requirements
    specification.

    Be sure to check the following artifacts for this:
      * bug reports
      * security advisories
      * commit message
      * mailing lists
      * anything else

    The answer field should be boolean. In answer_note, please explain
    why you come to that conclusion.
announced_date: '2020-07-15'
curation_level: 2
published_date: '2020-07-15'
forgotten_check:
  note: |
    The fix was to check the lockdown status before allowing a new ACPI table to be
    installed.
  answer: true
  question: |
    Does the fix for the vulnerability involve adding a forgotten check?

    A "forgotten check" can mean many things. It often manifests as the fix
    inserting an entire if-statement or a conditional to an existing
    if-statement. Or a call to a method that checks something.

    Example of checks can include:
      * null pointer checks7000
      * check the current role, e.g. root
      * boundary checks for a number
      * consult file permissions
      * check a return value

    Answer must be true or false.
    Write a note about how you came to the conclusions you did, regardless of
    what your answer was.
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 place them in an array like this
    CWE: ["123", "456"] # this is ok
    CWE: [123, 456]     # also ok
    CWE: 123            # also ok
autodiscoverable:
  note: |
    The core issue of the bug is related to injection and permissions. Both are things
    that could be discovered using something such as a fuzzer. It also appears that
    the discover of CVE-2020-15780 was done following the same process as a different
    bug. It seems that an automated tool could be created that would follow that
    general process to see if an injection is possible.
  answer: true
  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

    In systemd, the actually use OZZ Fuzz. If there's a link to it, add it here.

    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.
vcc_instructions: |
  The vulnerability-contributing commits.

  These are found by our tools by traversing the Git Blame history, where we
  determine which commit(s) introduced the functionality.

  Look up these VCC commits and verify that they are not simple refactorings,
  and that they are, in fact introducing the vulnerability into the system.
  Often, introducing the file or function is where the VCC is, but VCCs can be
  anything.

  Place any notes you would like to make in the notes field.
bugs_instructions: |
  What bugs are involved in this vulnerability?

  Please list bug IDs to https://bugzilla.kernel.org/

  Bug ID's can appear in several places:
    * Mentioned in commit messages
    * Mentioned in mailing list discussions
    * References from NVD entry
    * Various other places
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 required, but appreciated.
fixes_instructions: |
  Please put the commit hash in "commit" below.

  This must be a git commit hash from the systemd source repo, a  40-character
  hexademical string/

  Place any notes you would like to make in the notes field.
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: "After looking doing a surface level scan of most of the APCI related\ncommits
      from 2016 - 2020, it appears that all of the fixes were related\nto other aspects
      of the system no directly related to the aml write\nfunction. They are all updating
      other, unrelated issues, mostly due \nto small bugs with the state of the hardware
      components. \n"
    commit: 
  - note: 
    commit: 
  question: |
    Are there any interesting commits between your VCC(s) and fix(es)?

    Use this to specify any commits you think are notable in some way, and
    explain why in the note.

    Example interesting commits:
      * Mentioned as a problematic commit in the past
        e.g. "This fixes regression in commit xys"
      * A significant rewrite in the git history
      * Other commits that fixed a similar issue as this vulnerability
      * Anything else you find interesting.
order_of_operations:
  note: |
    The order of the events stayed the same. The only difference was the addition of
    the forgotten check.
  answer: false
  question: |
    Does the fix for the vulnerability involve correcting an order of
    operations?

    This means the fix involves moving code around or changing the order of
    how things are done.

    Answer must be true or false.
    Write a note about how you came to the conclusions you did, regardless of
    what your answer was.
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.

  This is not the same as published date in the NVD - that is below.

  Please enter your date in YYYY-MM-DD 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