Month of PHP Bugs Has Begun

An anonymous reader writes "The previously announced Month of PHP Bugs started three days ago, and already lists 8 security vulnerabilities in PHP and PHP related software. From the site: 'This initiative is an effort to improve the security of PHP. However we will not concentrate on problems in the PHP language that might result in insecure PHP applications, but on security vulnerabilities in the PHP core. During March 2007 old and new security vulnerabilities in the Zend Engine, the PHP core and the PHP extensions will be disclosed on a day by day basis. We will also point out necessary changes in the current vulnerability management process used by the PHP Security Response Team.'"

Comments

Defective by Design?

[Ckwop]

We see a lot of people use the phrase "defective by design" when talking about Vista and in that instance I'm pretty sure the use of the term is correct.

Having never used PHP but heard of its many security problems I'm wondering: Is PHP defective by design? If so, why so and how would Slashdot seek to fix it?

Simon

Re:Defective by Design?

[SCHecklerX]

Use perl instead :)

Not entirely joking. I use embedded perl for my own dynamic sites, and keep track of the lists, and can't recall any serious known flaws with that implementation.

The vulnerabilities that keep popping up (and the fact that I already know and am comfortable with perl, have CPAN, can develop quickly especially now that I have my own base modules set up, etc) are one reason that I never really looked into PHP.

Re:Defective by Design?

[julesh]

Is PHP defective by design?

It was. A lot of work has been done in the last couple of major versions to fix this, but still a lot of installations are crippled in the name of backward compatibility.

Most of what we're seeing here though is just run-of-the-mill sloppy coding. Create a lot of references to a variable and overflow its (16-bit) reference count? Please. That should never have happened.

Fortunately, it seems most of the bugs released so far don't affect the majority of installations. We have a number of 'executing arbitrary PHP code can let somebody own your web server' -- well, most of us don't let random people run arbitrary PHP code anyway. We have some 'deserialising arbitrary data can let somebody own your web server' issues too, but then there has been a long-standing warning that PHP's deserialise function isn't secure anyway, so that shouldn't affect anyone who's been paying attention. We have some issues with the Zend Platform, but I'm not sure how many people have that installed. So far, the only issue to affect me, is the phpinfo XSS vulnerability -- and that just meant I had to delete my phpinfo.php file that I kept in the root of each domain I host.

Re:Defective by Design?

[Anonymous Coward]

Uhmm, you are aware that all the phpBB forums out there use unserialize() on cookie data?

And phpBB is just one of many popular applications that do it...

Re:Defective by Design?

[julesh]

Uhmm, you are aware that all the phpBB forums out there use unserialize() on cookie data?

No, I wasn't. One more reason not to use phpBB, I guess.

Re:Defective by Design?

[julesh]

I think PHP has got beyond the stupid-design-flaws-causing-security-issues stage. Now, as you correctly point out, the major issue is endemic insecure programming practices and a lack of attention to bug reports.

How I wish we could just junk the language and start again with something else; unfortunately, market pressures being what they are, I'm afraid we're stuck with it, at least for the time being.

Re:Defective by Design?

[aaronwormus]

> I had to delete my phpinfo.php file that I kept in the root of each domain I host.

if you left an open phpinfo() on your server (giving potential attackers access to filepaths, module version numbers, configuration options, apache server configuration options), you have a lot more to worry about than a little XSS.

unfortunatly, you're not alone.

Re:Defective by Design?

[Dan Ost]

Actually, lots of people have abandoned PHP for Python and Ruby.

It may never completely go away, but there are alternatives to using it.

Re:Defective by Design?

[nuzak]

Done. http://www.caucho.com/resin-3.1/doc/quercus.xtp

Re:Defective by Design?

[julesh]

Actually, lots of people have abandoned PHP for Python and Ruby.

It may never completely go away, but there are alternatives to using it.

Not really. Most of us in the off-the-shelf web package software development industry are constrained to develop in whatever's available on the servers our clients are likely to choose. An informal survey suggests that of 5 popular hosting providers in my local area, only 1 offers anything other than PHP or Perl/CGI in their basic level package. With this kind of support, we'd be crazy to develop our software in any other environment. Sure, if you're building a site for yourself to use with a hosting provider you can choose, and your budget isn't so tight you have to go with the cheapest available, you get a choice of environments. Most people aren't in that situation -- most people have to use packaged software, and the packaged software vendors are in the same situation I'm in that it is market suicide to use anything other than PHP (or, for a significant minority, ASP.NET).

Re:Defective by Design?

[arodland]

Nope. Definitely defective by lack of design.

Re:Defective by Design?

[caluml]

mod_security and Hardened PHP can help with preventing future attacks that people don't yet know about.
Also, using something like GRSec, or SELinux can further restrict what people could do if they did end up with a shell on your webserver. Although whether it's worth the effort to set up for everyone is another question.

Month of bugs, will it change things for better?

[chabotc]

To be honest i'm glad that this month of bugs is happening, after all the previous news items about how the core php / zend team is refusing to colaberate with some ppl who are deeply concerned about php's security (and by this we do mean mistakes/faults in the php engine, not in bad php programming).

On the other hand, i bet a fair few of the released vunerabilities will be applicable for many websites that the company i work for hosts, and i know corperate policy doesn't include frequent updates to their envirioment, there's just to many sites, to many badly supported applications by/for customers, and just to damn many servers to work with easily, i can't imagine were the only such company with such problems... And it really makes me wonder if this will mean that many hundreds of our hosted websites will from now on be easily hackable by scriptkiddies

Should prove to be interesting times, and who knows maybe it will teach our admins to use yum/rpm's for their servers instead of compiling their own apache/php combinations :-)

Just in case..

[loconet]

To clarify, note that these bugs are related to the PHP core, not the language itself which may result in insecure applications. The statement that 8 security vulnerabilities in PHP and PHP related software is not referring to PHP software such as Wordpress. I mean seriously, I think I saw my dog hacking together a blog the other day using PHP. Everyone uses the language and not everyone has the background to know what they should and shouldn't be doing. In addition to its popularity, the language and its "libraries" make it easy for untrained coders to leave gapping holes in the code. Don't get me wrong, I love PHP (to an extend), I make a living out of it but any attempt at fixing "PHP related software" directly (ie: wordpress,phpbb,oscommerce,etc) would take more than a month.

Typical

[dysfunct]

Stefan Esser has found some interesting yet not too surprising vulnerabilities in PHP. All those scenarios described in the various vulnerability reports are very typical for the development process of PHP and many similar ones have already been found and reported. The same goes for the fact that many of those are simply WONTFIX. A perfect example for the general attitude regarding a remote code execution vulnerability cited here:

Because the PHP developers do not want to fix this anymore because it creates problems for companies providing closed source PHP extensions the only potential workaround is to manually change the size of the reference counter in your own PHP. However if you do so you have to recompile all your PHP extensions and cannot use closed source PHP extensions anymore.

I more and more get the feeling that the PHP developers themselves do not properly understand the vulnerabilities any more, which leads to improper and I even dare to say incompetent handling of reports and fixes (many of which simply get applied somewhere down the road without proper announcement or mentioning anywhere in the CHANGELOG) as well as seemingly ignorance regarding more complex vulns that are just as relevant as the glaringly obvious ones but simply not as mass-exploitable by script kiddies.

And *this* is the big problem that PHP is facing today regarding enterprise support. Maybe Jon Doe's blog installation is not as mass-exploitable by a script kiddie any more as it used to be some years ago, yet Big Company's CMS is still vulnerable to complex attacks by an experienced attacker who might use published attacks that security experts know about, yet end users do not.

Re:Parent isn't flamebait

[Aladrin]

So your webhost won't upgrade, and that's PHP's fault? PHP5 has been out a LONG time. Don't bother complaining about bugs in PHP4 simply because your website can't be bothered to upgrade. Find a decent webhost instead.

strpos() return FALSE when it can't find the 'needle'. http://us2.php.net/strpos Use a proper test (===) and you'll have all you need in a single statement.

Some people really LIKE dynamically-typed variables. It's not a bug or a problem. It's a design choice.

Your flamebait at the end (vbscript) does nothing to enhance your argument. Leave it off next time.

Oh Nose!

[FedeLebron]

"A deep recursion of PHP userland code will exhaust all available stack which leads to a sometimes remotely triggerable crash."

I've found a very similar bug in GLIBC!

int main(){
main();
}

This code will cause a segment violation!

Shock! Gasp! Horror!

Re:Oh Nose!

[julesh]

You do realise the difference between PHP and GLIBC, don't you? PHP is designed to have a "safe mode", which (according to the documentation) is supposed to allow a system administrator to run arbitrary code in the knowledge that it can't do certain things -- one of these things should be crashing the web server.

Re:Oh Nose!

[iluvcapra]

I've observed that a lot of complaints about modern PHP derive from the fact that it's a dynamic interpreted language, but that in many ways it behaves like a compiled, angry, shoot-yourself-in-the-foot language, like C.

PHP will segfault, just like C, if you recurse too far on the stack, but almost every other scripting language has a mechanism for catching a stack overflow as an exception and then letting the programmer handle it. PHP in this case just crashes; even C allows you to register a function to act if your program has a segmentation violation.

The long-complained-about static binding of class methods to their superclass, and not to child classes is in a similar vein. PHP does what C++ does: static methods execute in the scope of the class they're declared in, and not the class the method is called on. This is a requirement if your language is strict and compiled, like C++, but it's completely superfluous if you're running a dynamic language like PHP. It also makes a lot of tricks used by Ruby and Python developers to make slick frameworks basically impossible.

PHP taint what it should be

[atherix]

We see a lot of people use the phrase "defective by design" when talking about Vista and in that instance I'm pretty sure the use of the term is correct. Having never used PHP but heard of its many security problems I'm wondering: Is PHP defective by design?

Maybe. PHP is a wonderful interpreted language that makes creating a web application easy. The biggest problem with PHP are the entry-level programmers who don't understand the beast that is web programming.

Many PHP programmers don't understand the number one rule of secure web programming: All user data is evil. Anything that comes from an HTTP request can not be trusted. Heck, I don't trust it even after it has been stored in a database table or the file system. I would love to see a Perl-ish taint mode built into PHP that tells the programmer "This data has come from an insecure source. Please don't eval() it or unserialize() it or write it to disk. Cheerio."

Re:PHP taint what it should be

[Unknown Relic]

Well then, you'll be happy to know that Wietse Venema from IBM Research put in a proposal for taint support in PHP a couple months ago. I'm not sure if anything has come of it as there was a fair amount of concern that it would turn into another "Safe Mode" debacle, but from what I remember his plan was to essentially start work on a proof of concept implementation early this year and then take it from there.

Be Prepared?

[Mikenotmike]

Since properly coded PHP is still useful in many applications, what would be the best book to use as an up to date reference manual for the most secure method of coding with it?

Re:Be Prepared?

[brezel]

but from what I understand PHP does the whole ajax thing in a more fluid manner, is this incorrect? yes. php has nothing to do with javascript.

Why MOPB Matters

[gantry]

I have just analysed the last month's script kiddie attacks on my web server. 71% of them were to php-related URLs. When I first went through this exercise some years ago, the overwhelming majority of attacks were URLs related to IIS. The significance of this change cannot be overestimated.

Yes, a lot of the problems are sloppy coding, but too many are in the PHP core. How many web pages use the PHP-array-specific query-string
    ?foo[]=bar
- not many, you might think. How many use a PHP nested array
    ?foo[][][][][]=bar
- quite an unusual structure, you might agree.

The real stinger is that PHP will let this array be as deep as an attacker likes - and it's the same for a POST as for a query string, so there's no practical limit. An attacker can exhaust the space available for the stack, with several adverse consequences. This bug has a lot in common with the gravest bugs in PHP's history, in that it is a mistake in PHP's input processing: in this case, PHP trusts the sanity of user input. According to MOPB, Zend's attitude to this bug is "won't fix".

The arrogance of this attitude is breathtaking. PHP is now the most insecure package on my internet server, probably surpassing the old BIND 8 in the frequency and gravity of its exploitable bugs. I sincerely hope that Zend will get its act together and make security their number one priority. The predominance of PHP on the web is not theirs as of right - if they do not act, then either their product will be forked, or an alternative will take its place.

The nested array bug is described here:
http://www.php-security.org/MOPB/MOPB-03-2007.html