The wrong way to deal with privacy concerns · 2010-05-26 11:30 by Wladimir Palant
Generally, I am not the guy to pick on Google. I think that they usually bring out very solid (often brilliant) solutions and do a good job on the privacy front (meaning: far from perfect but significantly better than the competition). All the more surprising was their release of the Google Analytics Opt-out Browser Add-on which doesn’t quite live up to the expected quality.
One way to get outdated plugins on your computer · 2010-01-28 13:45 by Wladimir Palant
Only two days ago I wrote how browser plugins are the biggest security risk today. And yesterday I experienced first-hand how one would get outdated and insecure plugins installed. I installed Lexware Steuer 2009 (for the German readers: yes, that’s the one you get at Aldi and that always gets good marks in software tests). And then Secunia PSI went berserk warning me about various security threats on my computer. Turned out, this application installed without even telling me: Java Runtime Environment 1.6.0 Update 2 (released July 2007, current version is 1.6.0 Update 18), Flash Player ActiveX 9.0.124.0 (released April 2008, current version is 10.0.42.34), MSXML 4.0 SP2 (released June 2003, current version is 4.0 SP3).
The new browser security landscape · 2010-01-26 10:22 by Wladimir Palant
Brian Krebs came across one of those websites throwing a battery of exploits at users and took a close look at its administration page. It lists seven exploits, the two most successful ones being for Adobe Reader and Java, followed by two Internet Explorer exploits. At the far end of the list two Firefox exploits can be found as well. From what I understand, only one Adobe Reader vulnerability was unpatched at that time, all other vulnerabilities have been fixed already. For example, the Java exploit targets a security hole that was closed in December 2008, the exploited Firefox vulnerabilities have been closed in Firefox 1.0.5 and 1.5.0.5 respectively.
Mercurial over HTTPS - ouch, SSL isn't always secure · 2009-11-18 06:43 by Wladimir Palant
I set up my Mercurial server as HTTPS only. The idea behind it was that establishing a secure communication channel outweighs the disadvantages (server load, more traffic and somewhat slower pull operations) for a small server like that. But then I had second thoughts — I am using a StartCom certificate that isn’t yet accepted everywhere, what if somebody cannot pull the repository because of that?
AMO getting serious about add-on security · 2009-11-14 13:36 by Wladimir Palant
Good news: AMO is finally getting serious about improving security of add-ons. Several bugs that I filed almost a year ago and didn’t have time to follow up on have suddenly seen some movement, even to the point of setting a two weeks deadline to resolve the security issues (thanks, Jorge). Sure, this approach won’t make you new friends and one add-on author preferred to remove his add-ons rather than fix them. But it is really overdue to start enforcing policies.
Getting rid of Flash cookies · 2009-03-02 10:57 by Wladimir Palant
Pretty much every Flash movie on the web today uses Flash Player’s global storage feature to store data on your disk, similar to regular browser cookies. What makes this feature so problematic is the lack of proper control mechanisms. For example, for browser cookies I selected “Keep until I close Firefox” which makes sure that cookies can be set (no site functionality is broken) but won’t survive too long. But this setting won’t apply to Flash data. Same goes for the Private Browsing mode in Firefox 3.1, it has absolutely no effect on Flash. Note also that Flash data is the same for all browsers and all profiles.
Five wrong reasons to use eval() in an extension · 2009-02-06 11:35 by Wladimir Palant
One of the most overused JavaScript features is the eval() function. I have seen it used in very many extensions but only a few actually had a good reason to use it. So I want to go through all the wrong reasons one would use eval().
Vulnerable extensions survey · 2009-02-05 14:49 by Wladimir Palant
I spent in total something like 10 hours searching 78 of the top 100 extensions for signs of unsafe interactions with the web (yes, I failed downloading the extensions that are hidden behind a EULA, will do better next time). The result: 14 extensions with severe vulnerabilities (typically the kind of vulnerability that lets a web page take over your browser and even the computer if your browser runs with administrator privileges) and several proof of concept exploits. The good news: I don’t think that I missed too many vulnerable extensions, when I searched for more patterns I just kept finding new issues in the extensions that were already known to be vulnerable. More good news: none of the top 10 most popular extensions made the list. The bad news: many of the remaining extensions didn’t make this list simply because they don’t interact with the web or only interact with the web in ways that are relatively unproblematic. Some others were just too messy to get an overview in reasonable time, so it was impossible to understand whether questionable coding practices actually caused security issues.
Displaying web content in an extension - without security issues · 2009-01-28 10:02 by Wladimir Palant
Over the last few years I reported a bunch of security vulnerabilities in various extensions and by far the most common issue was: “Extension Foo allows execution of remote code in privileged context”. Typically, an RSS reader extension would take the content of the RSS feed (HTML code), format it nicely and insert into the extension window. The issue that is overlooked here is that the RSS feed could contain some JavaScript code and it would then execute with the privileges of the extension — meaning for example that it would get full access to the browser (cookies, history etc) and to user’s files. pdp discovered a similar issue in the Firebug extension that uses an HTML-based templating system and forgot to sanitize some input received from the webpage.
Deobfuscating JavaScript · 2009-01-12 15:28 by Wladimir Palant
A few months ago I read a post in the WebSense Security Labs blog: The Ultimate Deobfuscator. Wow, pretty impressive hacking effort and nice tricks to hook JavaScript eval() function and document.write() in Internet Explorer. But couldn’t you use JS Debugger hooks in Firefox to do the same thing with only a few lines of code? And then maybe even more generic because eval() and document.write() are certainly not the only ways to generate JavaScript code on the fly (out of the top of my head: changing window.location to a JavaScript URL, event handler attributes or setTimeout() with a string parameter).