Operating System and Web Apps Hacking

A lot can be learned from a hacker (albeit a convicted hacker).  Here are some of his thoughts on OS and web application security:

Securing a system:

I keep my services to a minimum, and I keep them updated. On my Linux box I use custom kernel hardening patches to make memory corruption bugs pretty hard to exploit. OpenSSH is firewalled and only accepts a connection from your ip if you visit a custom port-knocking page on my webserver. Basically the only service listening is apache, without PHP.

On my desktop and laptop I don’t have any services listening at all.

Public computers:

… I try to avoid public computers. If I really have to log in from an untrusted terminal I use otp authentication.

Modern website’s security:

Not very secure. SQL-injections are everywhere.

Discovering SQL injections vulnerabilities:

I don’t know of any specific papers, SQL injection is such a simple concept so you can pick it up in a matter of hours. The best method of finding them manually is to simply insert ‘ and ” union select(..” at random in parameters and see if things break.

Local source disclosure vulnerabilities:

Yes, sure. You can do a lot with config.php + phpMyAdmin.

What to do in a hacked machine:

1) Find a custom admin interface.

2) Get read access to a db from an SQL-injection.

3) Find tables corresponding to the custom admin interface.

4) Crack the admin password.

5) Log in and upload a new picture, containing PHP.

6) Exploit buggy custom cron-scripts that delete directories in /tmp once a day.

7) Wait for exploit to trigger..

8 ) Infect a binary on an NFS-share.

9) Wait for someone to use the binary..

10) Enjoy access to the main servers.

Something like that 😉

Operating System:

Personally I use Linux. I don’t consider Linux especially secure, just look at the number of local kernel root vulns found in the last year. I do however know that this is because there are so many people auditing Linux every day. I’d rather use an OS that has a few serious public vulns each year than one where the vulns are still there but aren’t found.

If you make a new operating system, how long it takes for someone to exploit vulnerabilities depend on how secure your code is and how much someone would want to exploit it. A local root vulnerability in QNX isn’t as “popular” as one in Linux, so more people are looking at Linux.

Tools used:

Exploits, network scanners, rootkits, google (perhaps the best network scanner).

And a voice recorder. They are essential when hacking banks.

More security holes:

Yes, I’ve written exploits for most types of bugs. Buffer overflows, format strings, int overflows. I have discovered some holes myself. Nowadays the most popular thing to audit is webapps. The age of remote root holes in popular ftpds is gone.

Government computers:

Personally I think that there are government agencies in the US, China, Russia etc. that have already backdoored each other to hell and back.

Stopping a hacker from coming in:

In short, if you have a network that is connected to the internet and someone wants to get in, they will eventually get in. If you are running the latest versions of all possible software you might think you are safe. But what if someone comes along with a 0day, or someone hacks the home computer of one of your administrators?

Tracing a hacker:

I got too comfortable with my setup and thought I was untraceable. It turns out that, given enough incentive, some people will analyze router logs from all over the world for months until they find you.


Make sure whatever PHP software you are using is always up to date. PHP stuff has a tendency to be written very poorly. Install some custom hardening patches like Grsec.

… I’m a big fan of Python. It’s much easier to write insecure software in PHP than in Python.

Security Industry:

I think has become less about knowledge and innovation and more about hype. Extreme hype. Everyone wants to make money off their name. Bugs become a commodity that is sold to companies that charge subscription fees for advance notice, etc..

Personally I am a blackhat. I loathe the cesspool of inflated egos that is the computer security industry. Therefore, I would never ever advise them to become “whitehats”. As for a more rewarding way to use their skill and curiosity, I can’t think of a good answer. Hacking into computers is simply the most rewarding experience I have ever had. I don’t see it as a problem if you are hacking big companies or governments for the sake of adventure, you are not out to hurt people.

Just make sure not to make money from your hacking, be it selling out to the security industry or selling botnet-stuff to russians. Both will destroy your passion.


I understand that ultimately some admin will have to take care of cleaning up after the breach, but it’s a part of their job. If one of the main reasons not to hack is that some administrator, whose job it is to maintain the servers, has to do his job.. I just don’t see that as a very compelling reason not to hack.


The incentive was the thrill of breaking into something that could sometimes have taken over a month of preparation. Looking at information that you weren’t supposed to be looking at. I suppose it’s the same feeling you get when solving any complex problem. It’s better than sex. I mostly worked alone, and I was not hired for anything.

Operating System hacking preference:

I almost exclusively hacked *NIX machines. Mostly Linux and Solaris, but also a lot of IRIX/HP-(S)UX/AIX. I would however definitely say that it is easier to hack a Windows PC, given their history of remote “root” vulnerabilities in default services.

OpenBSD is not secure at all. At least they changed the text on their front page to “Only two remote holes in the default install, in a heck of a long time!”. There’s a reason Theo DeRaadt has been hacked a number of times, his ego is enormously inflated. OpenBSD is 10 years behind grsec for example.

The most important part is the anti-exploitation techniques like ASLR, PIE, etc. What I meant to say was that GRsec has always been in the forefront when it comes to those. GRSec, RBAC and SELinux also have MAC capabilities but these are extremely rarely used correctly and to their full extent, since they are so hard to configure right.

Got Hacked?

Green Lock (via Flickr)The talk around Twitter right now is the phishing scam via Direct Message, as reported by many including Read Write Web, Mashable, and Chris Pirillo.  The victims include Twitter accounts for Barack Obama, Fox News, Britney Spears, and Rick Sanchez of CNN.   Getting their Twitter account hacked is a potential public relations nightmare.  The bait was a simple message to direct recipients to a fake Twitter login page, and enters their Twitter passwords.  Unsuspecting users went ahead and entered their information.  A similar trick was done in e-mail for the longest time using pages that looked like E-Bay, PayPal, or a banking site.

I get similar complaints with the websites that I maintain.  What can server administrators do to figure out who’s behind these attacks?   Here are the steps I take:

  1. Ask the business or customer when the suspecting hack happened.  Find out the exact date and time, if possible.
  2. Comb through the web server logs to find the IP addresses of the hackers using the date and time range reported by user.  For example, in Apache HTTPD, the file is normally called “access_log”.
  3. Most hackers try multiple times, in quick successions.   In this case, running through web logs through an analyzer like Webalizer or Awstats will reveal the IP address with the most hits, within a specified time range.
  4. Find out who the IP belongs to using tools like dig or nslookup.
  5. Report the offending IP address to the Internet Service Provider (ISP) as indicated by the lookup tool.  It can be done via email to postmaster@<isp.name> or abuse@<isp.name>.
  6. Depending on the severity, a fax or a phone call to the ISP may be required.  This is usually done when the hacking continues and there’s no indication of the ISP intervention to stop it.
  7. Start using the web server IP filtering features to blacklist the offending IPs.  For example, in Apache it can be done via Deny directive for doc-root in httpd.conf or .htaccess file.
  8. For known hackers’ IP addresses, make it permanent by blacklisting them in the firewall or router level.

Users do get complacent with their username/password.  They type (or even share!) passwords to others without thinking twice.  With more and more sites requiring a login, it’s easy to forget about checking the legitimacy of the page presented on the web browser.  Proactively, the web applications need to be modified to prevent login hacking such as:

  • Using Secure Socket Layer (SSL)   With SSL, most phishing sites will not bother with it because of the cost involved.  If logins are not done securely, users need to be extra careful.
  • Using OpenID, the open standards user login.  A site needs to be registered with OpenID to be able to use this service.  This removes the guesswork if the site is legitimate or not.

Hopefully the word is out for both users and web developers, to do whatever is required to secure login passwords.

Image Credit: Ashenzil