MFSA: Mozilla Foundation Security Advisories

Canonical source for Mozilla Foundation Security Advisories. http://www.mozilla.org/security/announce/

Writing new announcements

Announcements are written in Markdown or YAML. They should be named in the pattern announce/YYYY/mfsaYYYY-XX.EXT where YYYY is the 4 digit year, XX is the next in the sequence, and EXT is either md or yml.

Markdown Format

Once the file is created some data about the file should be added to the Front Matter. Front Matter is YAML encoded data surrounded by lines consisting of 3 dashes. Then the Markdown content can be added below the Front Matter. For example:

---
announced: April 29, 2014
fixed_in:
- Firefox 29
- Firefox ESR 24.5
- Thunderbird 24.5
- Seamonkey 2.26
impact: High
reporter: Abhishek Arya
title: Buffer overflow when using non-XBL object as XBL
---

### Description

Mozilla community member **James Kitchener** reported a crash in
DirectWrite when rendering MathML content with specific fonts due to an error in
how font resources and tables are handled. This leads to use-after-free of a
DirectWrite font-face object, resulting in a potentially exploitable crash.

NOTE: There is no need to include the MFSA ID in the front matter, it will be extracted from the file name.

NOTE: HTML is valid Markdown. So if you need extra features or classes, just add them.

Metadata spec

There are some required elements in the Front Matter data (metadata). They are:

announced: Date in Month Day, Year format
fixed_in: List of product names and versions (see example above)
impact: one of (Critical, High, Moderate, Low)
reporter: Name of bug reporter
title: Title of the advisory (may contain HTML).

Other data will be displayed, but the above will be expected in the template and styled correctly.

NOTE: You should NOT add a products: section to the data. The list of products is extracted from the fixed_in: list when imported into the website.

YAML Format

The YAML type is for advisories that are actually a roll-up of multiple advisories. These files are all YAML as opposed to the .md files which are only partially YAML. The following example should demonstrate the features of this file type:

announced: September 20, 2016
fixed_in:
- Thunderbird 45.4
title: Security vulnerabilities fixed in Thunderbird 45.4
description: |
  Text that will appear at the top of the file. ***Markdown*** allowed.
  
  ### An h3 is sometimes good
  
  Then you can explain further.  
advisories:
  CVE-2016-5270:
    title: Heap-buffer-overflow in nsCaseTransformTextRunFactory::TransformString
    impact: high
    reporter: Atte Kettunen
    description: |
      Short description <strong>with HTML</strong> and multiple lines!

      Can also have full breaks and ***markdown***!      
    bugs:
      - url: 1291016
        desc: The text for the bug link
  CVE-2016-5272:
    title: Bad cast in nsImageGeometryMixin
    impact: high
    reporter: Abhishek Arya
    description: A bad cast when processing layout with <code>input</code> elements can result in a potentially exploitable crash.
    bugs:
      - url: 1297934
  CVE-2016-5276:
    title: Heap-use-after-free in mozilla::a11y::DocAccessible::ProcessInvalidationList
    impact: high
    reporter: Nils
    description: A use-after-free vulnerability triggered by setting a <code>aria-owns</code> attribute
    bugs:
      - url: 1287721

The main part of the data is the same as the front-matter of the .md files. The primary difference is the advisories key, which contains a list of CVEs with their individual data. A CVE entry can have a list of bug urls. These can be:

• A bugzilla bug number. These will be converted to a bugzilla link.
• A comma separated list of bug numbers. These will be converted to a link to a bugzilla list of bugs.
• A valid URL will be kept as is.

Along with the url field of a bug, a desc may optionally be supplied. This will be the link text for the bug link. If it is not supplied the default is Bug {url}. For example, the link text for the bug in CVE-2016-5276 above would be Bug 1287721.

The main description field as well as those of the CVE entries can be multi-line and will be processed as markdown. The YAML spec provides different ways of enabling multi-line, but the best for this application is to use the | character after the : like you see in the example for the main description and CVE-2016-5270 above.

Bug Bounty Hall of Fame Files

This repo also contains data that bedrock uses to generate the client and web hall of fame pages. These are the YAML files in the bug-bounty-hof directory. The data format for these YAML files is rather simple. The only required field in the file is names: this is a list of data structures about each name in the hall of fame. For each name entry only name and date are required. The date field must be in the format YYYY-MM-DD. You can optionally add a url field and the entry on the page will link to this url. You are free to add other data to each entry (e.g. bug, organization), but at present bedrock will not use these items on the site.

Linter Script

There is a script in the repo called check_advisories.py that will tell you when you've gotten something wrong. It uses the same parsing algorithm as bedrock and so it should catch errors before they cause problems on the website. By default it will check all modified advisory and bug bounty hall-of-fame files in the repo. If you want to check them all you can pass the --all switch. And if you only want it to check the changes staged in git's index you can pass the --staged switch (this is mostly good for a git pre-commit hook).

You'll need a couple of dependency libraries. You can get them with the following command:

$ pip install ./

It's best to do that within a virtualenv. Then you can run the command:

$ check_advisories
Checked 3 files. Found 0 errors.

Use the --help switch to see all options.

Use as a git hook

The best way to use this linter script is to add a git pre-commit hook. Included in the repo is a shell script useful for this purpose. To install it issue the following commands from the root directory of the repo:

$ cd .git/hooks && ln -s ../../pre-commit-hook.sh pre-commit

After this if you attempt to commit a change to a file that has a problem being parsed, you'll be informed which file has a problem and the commit will be aborted.

Assignment and Release Process

Advisories are written and assigned as per the process described in the Security/Firefox/Security Bug Life Cycle/Security Advisories wiki page. Once advisories have a CVE id, and are pushed to the master branch of this repository (mozilla/foundation-security-advisories), they will automatically be published to CVE Services by GitHub Actions running the publish_cve_advisories script. This will also update already published advisories, for example in cases of a typo.