Code - 3

I just read an article about the recent wordpress vulnerability (if you're running wordpress, please update to 2.5.1 NOW), one point raised my attention: The attack uses MD5-collisions.

I wrote some articles about hash collisions a while back. Short introduction: A cryptographic hash-function is a function where you can put in any data and you'll get a unique, fixed-size value. »unique« in this case scenario means that it's very hard to calculate two different strings matching to the same hash value. If you can do that, the function should be considered broken.

The MD5 function got broken some years back (2004) and it's more or less a question of time when the same will happen to SHA1. There have been scientific results claiming that an attacker with enough money could easily create a supercomputer able to create collisions on SHA1. The evil thing is: Due to the design of both functions, if you have one collision, you can create many more easily.

Although those facts are well known, SHA1 is still widely used (just have a look at your SSL connections or at the way the PGP web of trust works) and MD5 isn't dead either. The fact that a well-known piece of software got issues depending on hash collisions should raise attention. Pretty much all security considerations on cryptographic protocols rely on the collision resistance of hash functions.

The NIST plans to define new hash functions until 2012, until then it's probably a safe choice to stick with SHA256 or SHA512.

I recently took the new CAcert assurer test. Afterwards, one has to send a S/MIME-signed mail to get a PDF-certificate.

Having the same problem like Bernd, the answer came in an RC2-encrypted S/MIME-mail. I'm using kmail, kmail uses gpgsm for S/MIME and that doesn't support RC2.

While this opens some obvious questions (Why is anyone in the world still using RC2? Why is anyone using S/MIME at all?), I was able to circumvent that without the hassle of installing thunderbird (which was Bernd's solution).

openssl supports RC2 and can handle S/MIME. And this did the trick:

openssl smime -decrypt -in [full mail] -inkey sslclientcert.key

It needed the full mail, which took me a while, because I first tried to only decrypt the attachment.

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/

Today I found a note about the movie The Codebreakers. It's a free-licensed (cc-by-sa) documentary about free software in development countries.

It brings up different examples about successful usage of free software in different parts of the world. Worth watching.

I recently added some stuff to gentoo for openstreetmap and gps-related work.

For one, the java openstreetmap editor josm now has ebuilds. josm and josm-plugins, the first only installs the program itself plus language packs, the second installs most of the josm-plugins available. They can be enabled within the configuration.
I was a bit unsure how to handle it, as I first thought about adding some basic plugins to the josm-package itself. But as the opinions on what »basic« plugins are seem to differ a lot, I decided to do it this way.
Another new package is gebabbel, a gui-frontend for gpsbabel. gpsbabel is a commandline-tool that implements various proprietary gps coordinate formats and allows access to many gps-devices (e. g. garmin). Beside it can be used to filter and convert gps-tracks.

More to come. Probably also interesting stuff in portage is gpsdrive (which has some osm-stuff in svn, but not yet in a release), marble (world-view-tool for kde, osm-support is planned within the next months). Other stuff not yet in portage, I plan to make packages in the future: tiles@home, qlandkarte, mapnik and probably everything it takes to run an osm-server.

A bit offtopic, as gentoo doesn't run on mobiles (yet): Mobile Trail Explorer is the only free (as in freedom) software I found for J2ME-mobiles to create gps-tracks. It's a bit alpha, lacking some features and unstable, but it's free, so I hope it'll become better soon. It's a cheap way to get gps-tracks, assuming that you already have a java/bluetooth-mobile and you can get a gps-mouse starting at about 50 €.

If you have more suggestions for gps/osm-related stuff, feel free to open requests on the gentoo bugzilla and add me to the cc.

I'm happy to announce that I mentored Christian Hoffmann to become a new Gentoo Developer.

Christian did some PHP-security work for Gentoo recently, which is very important due to the high amount of security issues php had recently. Welcome on board and continue your good work.

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.

Es scheint heutzutage mehr und mehr zur Selbstverständlichkeit zu werden, dass immer dann, wenn Politik sich »mit Computern« beschäftigt, vor allem die sich besonders laut hervortun, die gleichzeitig unmißverständlich klarstellen, dass sie vom Thema eigentlich garkeine Ahnung haben. Das haben Schäuble und Zielke bei der Debatte um den »Bundestrojaner« nur allzu deutlich getan, das zeigt sich auch bei der unsäglichen Debatte um sogenannte Killerspiele.

Und in dieser Tradition geriert sich auch das heute beschlossene Gesetzeswerk zur Bekämpfung der Computerkriminalität. »Hacktools« werden verboten.

Frage 1: What the hell is a hacker?
Es gehört wohl zu einer der Fragen, bei der 5 Fachleute mindestens 7 Meinungen haben. Das reicht vom Verständnis des Hackers als jemandem, der sich kreativ-spielerisch mit Technologie außeinandersetzt über die Unterscheindung in White- und Blackhats (bzw. Hacker und Cracker) bis hin zum populären Verständnis des bebrillten Jugendlichen, der NASA-Rechner hackt, dazwischen in den verschiedensten Schattierungen der revolutionäre Kämpfer für Informationsfreiheit (23).
Ein solcher Begriff, sollte man meinen, ist wohl denkbar ungeeignet, um in einem Gesetzeswerk aufzutauchen.

Frage 2: Und was ist jetzt eigentlich ein »Hacktool«?
Nehmen wir großzügigerweise an, es handle sich um die Vorstellung des Hackers als jemandem, der illegal in Rechner eindringt, sich Daten beschafft und Webseiten verändert. Nun wird auch noch erläutert, "Der Gesetzgeber wird die Auswirkungen der neuen Strafvorschriften genau zu beobachten haben. Sollten doch Programmentwickler und Firrmen, die nicht aus krimineller Energie heraus handeln, durch diese neuen Strafvorschriften in Ermittlungsverfahren einbezogen werden, wird auf solche Entwicklungen zeitnah reagiert werden müssen."
Das beruhigt ungemein. Letztendlich ist wohl zu erwarten, dass es Sache der Gerichte bleibt, zu entscheiden, ob nun der Austausch von Trojanern und Viren zum Zwecke der Sicherheitsforschung darunter fällt, ob ein Tool wie Nessus oder johntheripper schon kriminelle Energie impliziert.
<Sarkasmus>Bekanntlich erwiesen sich deutsche Gerichte in der Vergangenheit immer besonders kompetent und informiert, wenn es um die Beurteilung von derartigen Fragen ging.</Sarkasmus>

Desweiteren sei als interessante Sidenote noch bemerkt, dass auch die »Bürgerrechtsparteien« FDP und Grüne geschlossen für den Entwurf stimmten. Lediglich der SPDler Jörg Tauss gab sich als Dissident gegen den Fraktionszwang und votierte mit der Linkspartei dagegen.

Bin gerade auf der Abschlussveranstaltung und Zeit für ein kleines Feedback.

Man hatte etwas den Eindruck, dass deutlich mehr Aussteller als Besucher anwesend waren. Lag vermutlich an den hohen Preisen, weswegen kaum Laufpublikum anwesend war. Das heiße Wetter tat sein übriges und führte auch dazu, dass die Menschen an den Infoständen meist etwas erschöpft aussahen ;-)
Kontakte gab's so nur wenige, einige Interessenten an CAcert, ein paar Ubuntu-CDs gingen weg. Trotz allem würd ich mich nächstes Mal wieder beteiligen.

Weitere Bilder sind eben auch hochgeladen worden.

Up until recently, I had URLs of the form /item/number, which is due to the reason that this was the URL-naming-scheme of bblog, an ancient blogging software I used years back. Now serendipity supports URLs with the title (minus problematic charakters), which is much better for search engines, because they often rate words that appear in the url better. Now, changing the URL after years of blogging doesn't seem appropriate (probably hundreds of links, trackbacks, bookmarks), so I needed some migration path. Serendipity doesn't support two url schemes out of the box, so I hacked some bash to do the trick. This will generate (after changing the url) forward rules (add them to .htaccess after the s9y-stuff), which send a »moved permanently«-answer. This has do be done only once, as there won't be links on new articles with the old scheme.
It's a fast hack and it probably doesn't fit in other situations without changes, but it's a nice example how fast you get somewhere with some bash and sed magic:

for i in `seq 1 31`; do

        wget --quiet -O - http://www.hboeck.de/archives/P$i.html|grep serendipity_title | \

        sed -e 's:^.*href="\([^"]*\)">.*$:\1:g' | \

        sed -e 's:^/\w*/\(\w*\)-.*:RewriteRule ^item/\1 \0 [L,R=301]:g'

done

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

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:

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