Bugzilla CVE-2015-4499: All Your Bugs Are Belong to Us

https://blog.perimeterx.com/bugzilla-cve-2015-4499/

by Chris911 • 11 years ago

123 35 11 years ago

blog.perimeterx.com

fein• 11 years ago

Incredibly interesting, and incredibly simple. Very cool stuff.

I do wonder... Why on earth is domain based privileges ever a good idea? There should be a proper roles system behind the scenes which doesn't grant privileges based on an email domain.

pilif4• 11 years ago

There is a proper roles system. But as a shortcut, roles are assigned by domain. It's either this or manually creating/accepting accounts if they need privileges other than the default.

In this case, they could get away with the shortcut (if you exclude the MySQL misconfiguration), so that's what they have done.

geofft• 11 years ago

Because the business requirement is "Anyone from this company we are partnering with, which has signed a mutual NDA at the company level, should be able to see these bugs," and "The local Bugzilla admins shouldn't be involved in the hiring processes of that other company," and "No, they don't have a public facing identity management system we can integrate with."

ScottBurson• 11 years ago

You know, if you're going to use this meme, you should get it right. It should be "all your bug are belong to us" [0]. Yes, it's ungrammatical -- that's the point!

[0] https://en.wikipedia.org/wiki/All_your_base_are_belong_to_us

rubbingalcohol• 11 years ago

what you say?

EpicDavi• 11 years ago

I would argue that in the original, "base" was referring to a singular object and was not reduced down from "bases" (plural) to "base" (singular). Therefore, I do not think it is necessary to reduce "bugs" to "bug".

I know you are joking but if we are being pedantic here, "all your swarm are belong to us", would be more apt.

EDIT: Instead of swarm, a name for a group of bugs (errors) would be appropriate.

saint_fiasco• 11 years ago

So "All your base" is Engrish for "The entirety of your base", not "All your bases"?

ben0x539• 11 years ago

I don't speak Japanese, but according to whoever translated it for Wikipedia it was really "bases":

https://en.wikipedia.org/wiki/All_your_base_are_belong_to_us...

kijin• 11 years ago

I'm not sure which is worse: not validating your data, or silently truncating invalid data.

It seems that the fix [1] was to limit the length of email addresses to 127 characters. That'll do for the time being, but they really should pay more attention to database warnings. MySQL does all sorts of stupid things, but at least it tends to emit warnings when it's being stupid. Catching those warnings and turning them into exceptions should go a long way toward preventing bugs like this.

[1] https://git.mozilla.org/?p=bugzilla/bugzilla.git;a=commitdif...

DCoder• 11 years ago

MySQL can turn those warnings to exceptions on its own, via sql_mode [1]. New installations of MySQL 5.6 have this behaviour enabled by default on InnoDB tables.

[1] http://www.tocker.ca/2014/01/14/making-strict-sql_mode-the-d...

harshal• 11 years ago

It looks like the devs are doing exactly the right thing: Fixing the immediate problem quickly on released branches and following up by stricter checking in the development version (which looks like it will need a lot more changes) See: https://bugzilla.mozilla.org/show_bug.cgi?id=1202447#c17 https://bugzilla.mozilla.org/show_bug.cgi?id=1202509

elchief• 11 years ago

1. This is mostly MySQL's fault for default silently truncating values longer than the requested length. Postgres and SQL Server don't do this, but that's all I tested

2. Lack of email validation by Bugzilla. Emails are max length 254, though this might not have been official when the code was written. See https://stackoverflow.com/questions/386294/what-is-the-maxim...

3. Consider using an HMAC'd URL for registration email links instead of putting a token in the database, as per https://neosmart.net/blog/2015/using-hmac-signatures-to-avoi...

stinos• 11 years ago

1. I copletely agree it isn't exactly the best design decision, on the contrary, but the developpers are still too blame as well in my opinion. They chose the datatype so they should have read the documentation, especially the caveats like this, and they should have done something to deal with this.

This applies more generally. There are a ton of programming languages, standard libraries and APIs out there with weird/confusing/exceptional/undefined-behavior-invoking types and functions depedning on how they are used so a sane developper should alwyas check this and handle accordingly, even though it might lead to more code to handle edge cases than to the actual expected main code path.

pilif4• 11 years ago

Will the DB raise an exception? Will it crash? No – It automatically truncates the data so it fits the column size.

If you write software, never be "helpful" and try to fix problems with input data you can't handle. You have no idea whether the fix you have in mind is going to be appropriate in all situations and there is no guarantee that your users are going to acknowledge the warning you might (or might not) issue in that case (case in point: MySQL does fire warnings, but many libraries don't even expose them to the user, so even if they wanted to check for warnings after every statement, they couldn't)

"Fixing" broken input data is nothing but actually corrupting data because after the fact there is no way to know what the original was, nor is there a way to know whether the "fixed" data was actually fixed or whether it has been that way to begin with.

If you are in a position where you can't do something based on the input data, then blow up. That way you help users to avoid ever having to deal with corrupted data (or all their private bugs exposed to the public like what happened here)

bkor2• 11 years ago

Not really the full story. Bugzilla explicitly disables strict mode (due to another problem). Pretty stupid to have done that!

See for details https://bugzilla.mozilla.org/show_bug.cgi?id=321645#c20

PS: I wrote the patch to disable strict mode.

makomk• 11 years ago

If I'm reading that correctly, the problem was that some MySQL versions couldn't actually restore database dumps they created using mysqldump if strict mode was enabled. That's a pretty ugly bug.

dspillett2• 11 years ago

If you write software, never be "helpful" and try to fix problems with input data you can't handle.

Yep. Accepting bad data in any way is a bug, not a feature, and it isn't always (I'd suggest it isn't commonly) intentional: for instance mySQL used to accept dates like 2015-02-30 simply because its internal date format permitted it rather than because they were explicitly allowing it - it was an accident not an attempt to be helpful.

Accidental bugs that accept bad data are often indistinguishable from intentional "help", and can get passed up through a stack of calls (App A uses library B that wraps library C which calls service D that uses library E...) so even if the help is very well documented at source that knowledge is usually lost as you move up the chain and the application dev is left with a library that accepts bad data unbeknownst to him/her which could end up masking a serious bug that will bite them later.

"Fixing" broken input data is nothing but actually corrupting

Exactly. The old "be strict in what you send, but generous in what you receive" is often misinterpreted - you should only be generous in what you receive if everything you receive can be properly handled all the way into your stack and all the way back out again, and never be generous enough to accept bad data. Back to the date example: yes, accept any unambiguous date format the user might throw at you, but never accept an invalid date.

If you are in a position where you can't do something based on the input data, then blow up.

Definitely. If something could fail it should fail as early as possible, and not quietly in development (caveat: failures should not be outwardly verbose in production for security reasons), that way you are more likely to catch problems early, before they compound into something worse.

josephcooney• 11 years ago

I don't think it is quite that clear cut. See, for example, Postel's Law AKA the Robustness Principle.

Be conservative in what you do, be liberal in what you accept from others

https://en.wikipedia.org/wiki/Robustness_principle

MichaelGG2• 11 years ago

MySQL is basically taking Visual Basic's "On Error Resume Next" approach. Which is also what a lot of JS seems to be doing, too, based on limited experience.

praseodym• 11 years ago

Indeed, and in some cases this can have side effects like skipping certificate validation: https://github.com/github/hubot/issues/1046

derf_• 11 years ago

It is important to point out that access to security bugs (the ones that contain descriptions of unpatched vulnerabilities) is not automatically granted to all Mozilla employees, so simply having an @mozilla.com e-mail is not enough to get information on how to exploit Firefox.

It is enough to get access to potentially sensitive partner information (as can be seen from the posted screenshot), but those are usually a different class of bugs from security bugs.

Further, we now classify security bugs by the area of the code they affect, and give engineers access to just the areas for which they are responsible, rather than blanket access to all security bugs. This is a process that began even before the recent attacks, but we have been pushing it more aggressively in their wake.

vog2• 11 years ago

I never understood why people use MySQL for anything where correctness is important. The auto-truncaction is only one of many nasty surprises.

Did you know that auto-truncation also kicks in if your columns values are small, but you run a CONCAT on them? That was a nasty surprise when a generated a CSV line on DB side, which by bad luck was truncated immediately before a comma, so the result was correst, just the jast few items were missing. And ever looked at the handling of invalid dates? Not to mention what happens if you forgot to specify a column in your GROUP BY clause, but use it in the SELECT part ...

To anyone who is so brave to write their application using that database: Be sure you know all those issues and take care of them in your application. Or make sure you aren't affected by them. Or, switch to a high-quality database!

I switched to PostgreSQL a long time ago and never looked back. These people care about exactness, quality and clean extensibility in all directions, even user-defined index structures are possible (GIN, GIST). The problem that PostgreSQL was slower than MySQL disappeared as soon as MySQL became transaction safe with InnoDB, because it was now a fair comparison as PostgreSQL was transaction safe from the very beginning. Also, the PostgreSQL project management is one of the best I have ever seen, meeting schedules, regular commit fests, quality-driven, honest beta releases, and so on.

rimantas• 11 years ago

  > I never understood why people use MySQL for anything where
  > correctness is important.

They probaly know how to configure it.

vog2• 11 years ago

This doesn't seem to be any harder than MySQL, it's just a bit different. Also note that PostgreSQL can perform "peer" auth, so you don't have to fiddle with DB passwords unless you really want to access your DB over a network.

Install package:

    apt-get install postgresql-9.4

Become PostgreSQL admin:

    su - postgres

Create a DB user who is allowed to create databases (assuming your app will run as user "someuser"):

    createuser -d someuser

    exit
    su - someuser

Create your database:

    createdb somedb

Play with your database:

    psql somedb
        CREATE TABLE ...

gohrt2• 11 years ago

If you are going to the effort to learn all the ways you need to tell MySQL to not corrupt your data, you may as well spend that energy learning PostgreSQL

tomvangoethem• 11 years ago

For anyone interested in similar issues: here you can find a report for a vulnerability in Phabricator with exactly the same cause (truncation by MySQL), and pretty much the same result: https://hackerone.com/reports/2224

If Bugzilla would allow non-ASCII characters in the email address, MySQL's truncation behaviour with astral symbols (e.g. 𝌆) would probably have lead to a similar vulnerability as well. (It did so in Phabricator: https://hackerone.com/reports/2233)

bugmen0t• 11 years ago

The bug impact description is completely false. Mozilla has "corporate confidential" bugs behind the @mozilla.com email check, but everything with a security rating is restricted to specific accounts that have been explicitly vouched for.

Bugzilla CVE-2015-4499: All Your Bugs Are Belong to Us

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