TYPO3 4.3 system extension saltedpasswords - manual available

Posted in TYPO3/ on February 05, 2010 by Marcus.

TYPO3 version 4.3 has brought a lot of new features. It's out since December 2009 and you've probably tried it or you're already familiar with all the new gimmicks.

I'm glad that the new system extension saltedpasswords has made it into the core. It allows to store passwords of TYPO3 user accounts as salted hash. With all these web sites that allow to "retrieve" the origin of a md5 hash, it's important that TYPO3 keeps up with the progress in security industry. With salted passwords we catch up with other content management systems like Drupal or Wordpress.

The main advantage of salted hashes is the fact that it makes pre-computed rainbow tables useless. Someone who's interested in retrieving the original password for a salted hash is basically cursed to run a brute-force attack. This is much more expensive in terms of time and computing power than looking up a hash in a pre-computed table.

What makes salted hashes so special? Every to be hashed plain-text password will concatenated with a random string (the salt). This salt is different of each user password stored in the CMS's database. Then, the hashing and concatenation will be done multiple times. By default, TYPO3 does that exactely 16384 times for each password. You now understand that dealing with salted passwords is a lot more secure than a typical md5 hash. Still, you're advised to wisely choose your password. Don't use a dictionary word; in best case it's a passphrase consisting of upper- and lowercase letters, numbers and special characters.

Service announcement - Updated blog software

Posted in TYPO3/ on February 05, 2010 by Marcus.

Dear readers!

I've updated the TYPO3 extension T3BLOG to the latest version, have fixed some bugs (patches are in the mantis bugtracker for project t3blog) and made further modifications on it to fix my special needs.

If you still encounter any bugs, please drop me a note.

In addition, the feed url has changed. It's now http://secure.t3sec.info/feed/rsstype/2.0/rsscontent/post/pagetype/100/. However, the old url stays valid. Bonus: Now, the feed is a full text one (without any html structure).

Thanks to Dmitry Dulepov for his great work on TYPO3 extension T3BLOG. This extension has undergone a complete security review and now it's really safe to use.

No re-use of version numbers in software development

Posted in TYPO3/ on January 30, 2010 by Marcus.

You certainly know that in software development, version numbers (e.g. 0.2.27) are used to identify a specific development version of a software product.

We, the TYPO3 Security Team recently had to work on an issue where the TYPO3 extension developer thought to be very smart in regards to the version number of his extension. We contacted him and reported a specific version number (like 0.2.27) to be vulnerable. After a few days, we faced a "new" version 0.2.27 of his extension cleaned up from vulnerabilities in the TYPO3 extension repository (TER).

Unfortunately, this happens quite occasionally in the TYPO3 world. It's a pity that the TYPO3 infrastructure (TER) does not prevent such overwritings of extension versions.

This is really bad development style. Let's assume you maintain a software product in which a bug occurs in version 1.3.15. You fix it, overwrite this version and now 1.3.15 is clean. A new report comes in again reporting 1.3.15 to be defective. You now face a problem. Which version contains the bug, the originally one or the modified one?

Additionally, in the TYPO3 world there's another drawback. The TYPO3 CMS has a so-called extension manager that allows to install/remove/update third party modules within the administration interface. This manager will not report a to be updated extension if you simply overwrite an already existing version.

Finally, considering security incidents, things get even worse. There are a lot of security service providers like Secunia that keep track of security advisories and so keeps you up-to-date on security vulnerabilites in products you might have deployed. Furthermore, there are "vulnerability databases" like NVD that describe and rate vulnerabilities in software products.

So in an security advisory you obviously want to clearly state that version 1.3.15 is vulnerable and version 1.3.16 is the fix for this vulnerability. You don't want to say that version 1.3.15 published until January 15, 2010 is vulnerable and any later available version of 1.3.15 is safe to use. This make things unnecessary complicated.

Do proper software development, do not overwrite version numbers! There are unlimited numbers to be used in version numbers; don't get stingy with new version numbers, you won't use them all up!

Who is trustworthy?

Posted in TYPO3/ on December 05, 2009 by Marcus.

Interesting question, isn't it?

First let me explain which roles interact with a TYPO3 installations.

• TYPO3 installation administrators
• website editors a.k.a. backend editors
• privileged website users a.k.a. frontend users
• unprivileged website users

Most of us will agree that last two roles are not trustworthy. This is obviously the case for unprivileged website users as a nobody knows who will finally access the website in the internet. A frontend user registration in most cases will accept any user. Registering process consists of filling form fields with user data (email address), following a confirmation link in a mail generated by the TYPO3 system and you're done.

Now we're getting to a more disputable role, backend users. During incident handling in the TYPO3 Security Team we see a lot of TYPO3 extension developers making false assumptions. They assume that all backend users are good guys and therefore will gracefully accept any input (e.g. plugin configuration).
This might be true for a website of a kindergarten located in a small village where one kindergarten teacher takes care of the website as backend editor.
Please think bigger! TYPO3 is considered to be an Enterprise CMS. TYPO3 is used for educational institutes (universities) with dozens of website editors (professors, employees, student employees). It is used for huge NGOs and for multi-national companies with distributed departments worldwide. Then you are dealing with hundreds of backend users.

In case of such huge deployments it's simply impossible for an admin or a team of admins to know everybody personally. Decisions which one to grant editor rights are most likely not to be taken by admins any more.

It does take only one curious guy who's trying to exploit a vulnerability to get admin rights, too.

So please, dear extension developer, assume that website editors a.k.a backend editors are not trustworthy! Validate their input, do plausibility checks!

TYPO3 admins might be considered as trustworthy as they are able to do anything anyway.

 

TYPO3 extension developers:
Remember one important rule: do not trust user input!

TYPO3 admins:
TYPO3 allows extensive configuration of what specific roles are allowed to do and what is disallowed. Use it! Only grant the least necessary rights that are really needed. Be careful with allowing HTML or TypoScript configuration for website editors.

Beware of Subversion leftovers in production websites

Posted in others/ on November 03, 2009 by Marcus.

Every once in a while, old and known problems are newly discovered. The same recently happened for the Subversion leftover issue.

If you checkout projects from a Subversion server, subversion creates a ".svn" directory that contains some data. Using this ".svn" folder, subversion is able to determine if local changes have been made, etc ...

In case, your webserver does not reject access to ".svn" folders, a malicious user will have access to listings of webserver directories even if you try to prevent that with the "DirectoryIndex" directive. In addition, a malicious user might get hold of unparsed script code in plain text depending on your webserver configuration.

There are at least two valid solutions:

• Use dedicated command "svn export" for deployments and you'll receive a clean directory tree.
• Reject access to ".svn" folders in your webserver configuration.

A valid entry in your Apache config file (httpd.conf/apache2.conf) would look like this:
#
# Prevents access on SVN specific folders
#
<Directory ~ ".*\.svn">
    Order allow,deny
    Deny from all
</Directory>