Nick on Security

Deleting your personal information before selling your computer

2011-05-04T15:40:00.000+01:00

So you’ve decided to sell your computer, I guess you’ll be wanting to erase all your personal information before you let it out of your hands then?!

I'm going to assume that most of you are Windows users so this guide is tailored to it. Now you have two main options before you sell your computer, one is to completely erase the hard drive, the other is to only erase specific personal files securely. Both methods use free software available to download from the internet.....

As this is article deals with data deletion the following disclaimer is unfortunately a must – Any action you take as a result of this article is your own responsibility. I will not be held accountable for content on external links or any loss of data. Please check all your downloads with antivirus software. This is a guide and you are advised to research further if you have any doubts as to what these directions will do.

OPTION 1: Securely wipe the entire hard disk including the operating system.

This is the best option from a security point of view but this will erase ALL the information on the hard drive and will mean that the computer will be unusable until the new owner (or you) installs an operating system (windows, Linux etc.) on to the hard drive. This is only suitable If you are absolutely sure that you no longer need any data on the computer and that you can sell it without an operating system or you can install an operating system yourself.

1.) Backup anything you need to keep!

2.) Download (but do not open / run) Darik's Boot and Nuke ("DBAN") from:-

http://www.dban.org/download

Documentation and screenshots can be found at:-

http://www.dban.org/documentation

3.) DO NOT OPEN the file – Burn it to a CD or DVD - your going to use it as a boot disk.

4.) Put the CD / DVD in the computer then restart the machine.

5.) You should be presented a screen to select which type of erase to perform.(If not you may need to configure your bios to boot from CDROM first). For personal needs I'd suggest DODShort method would suffice but you should read the documentation for more information.

6.) When its finished your hard drive will be completely wiped.

OPTION 2: Securely delete personal information / specific files and slack space.

This option allows you to use an application called Eraser to securely erase specific files and folders.

1.) Backup anything you need to keep!

2.) Download Eraser from - http://www.heidi.ie/eraser/

Documentation for eraser is included in the download and there is also a forum - http://bbs.heidi.ie/viewforum.php?f=30

3.) Install Eraser

4.) Right click on the folder/file that you want to securely delete and there should be an option similar to “Erase with Eraser” - when you select this it will be securely erased and should not be able to be “undeleted”. More detail is contained with the Eraser documentation.

5.) Also use the “Erase File Slack Space” option in Eraser. This will ensure that any previous files deleted in a standard Windows method will also then be securely erased.

I hope you've found this useful.

As always, please feel free to leave a comment.

I'll update this with additional information if required.

How to generate, use and remember a strong password or passphrase

2011-01-13T12:30:00.003+00:00

We use passwords every day and on lots of different systems, so its not surprising that it’s a bit confusing trying to choose unique, strong passwords that can be easily remembered. In this post we’ll first deal with the criteria of a fairly good password then we’ll look at a few tips to help you choose good passwords that you can easily remember....

Don’t use a password that’s easily guessable - In other words don’t use the names of your family, friends, pets, hobbies, interests etc. It’s possible that words and names associated with you can be combined into a dictionary so that a password cracking program can use them. In fact don’t use any single word on its own that is in a dictionary.

Use a password that is complex and long enough - I’d suggest that your passwords are at least 8 characters long and contain upper case letters, lower case letters and numbers. You can also use special characters such as “£%&@ but a lot of websites will not allow this for their passwords. There’s technical reasons why all this is all important which I won’t go into just now. When it comes to passwords, the longer the better.

Use different passwords for different systems and websites - Don’t use the same password for all of your accounts. Your Facebook login username is generally your email address, so if I obtain the username and password for your Facebook then I could access your email if you’re using the same passwords for both. Also try not to use incrementing passwords where you just put a number or a month after the password.

How to remember your password or passphrase:-

Use a passphrase- A passphrase is like a password but is generally longer and stronger than just one word. It could be a combination of words that are not related such as the words ‘satsuma’ and ‘telephone’. An example of applying the rules above for choosing a strong password with these two words could be - SatSuma4telePhone

Use a rhyme, sentence or song - A good way to generate a strong password is to take the first letter of every word in a random sentence, song or rhyme and then add a number. i.e. ‘Mary had a little lamb, whose fleece was white as snow’ could become a passphrase of – Mhall4wfwwas

Use online tools to generate strong random passwords or check the strength of your passwords- There are a number of online tools available to do this such as - http://www.pctools.com/guides/password/ and https://www.microsoft.com/protect/fraud/passwords/checker.aspx

Save your passwords in a password safe so you don’t forget them-There is quite a lot of free software available, called password safes, that allow you to store all your passwords in one place so that you can recall them if you forget any. I quite like http://passwordsafe.sourceforge.net/

Getting Started with Computer Hacking

2010-12-29T15:12:00.011+00:00

I often get asked questions around how I became an Ethical Hacker & Penetration Tester and I usually bore the person that asks by explaining how I made a transition from a more traditional role of the systems analysis through to information security by a combination of luck, judgement, self teaching and of course some qualifications along the way.

Now I’m sure that my short bio is absolutely entrancing but I’m guessing that when people really ask that question they are in fact asking ‘How do I learn to hack computers?’ or ‘How do I become a hacker?’

Well all the information you need is out there on the internet and in bookshops, regardless of whether you choose to use it ethically or not.

I advocate responsible disclosure- http://en.wikipedia.org/wiki/Responsible_disclosure which ensures that if the bad guys find something exploitable (hackable) then all the good guys get to know about it and can put the pressure on to ensure it gets fixed.

I’ll include a link to the Amazon store for reference but if you don’t want to buy them you may be able to order them at your local library.

So without further ado here’s a list, in no particular order, of some recommended books to get you started on your way to a career in hacking… Hopefully as one of the good guys (White Hats)… As always, please feel free to leave a comment.

Nmap Network Scanning: The Official Nmap Project Guide to Network Discovery and Security Scanning

Nmap is a fast, well supported and industry standard tool for port and service scanning. Which basically means you should use it to work out what is running on the target computer so you can start to identify vulnerabilities. It’s a free tool available to download here - http://nmap.org/ - and although the online documentation is good, it’s best to take a look at this book to get the most from Nmap.

Hacking Exposed, Sixth Edition: Network Security Secrets and Solutions

This book mostly deals with the methodology of a hacking attack to infrastructure rather than web apps - think hacking servers, routers, operating systems, Wifi etc. It’s fairly technical in parts so you may need a good MS Windows and Linux handbook to accompany them. It also suggests ways to mitigate risks so the good guys can fix the issues. There are a number of other 'Hacking Exposed' books dealing with Web Application, Windows, VOIP and many more specific technologies. All are worth a look.

Approaching Zero: The Extraordinary Underworld of Hackers, Phreakers, Virus Writers, and Keyboard Criminals

This does not give any information on techniques or practical information for hacking, however, it is a good read as a story and has real world examples of the beginnings of phone phreaking and hacking going back to the 70’s

The Art of Deception: Controlling the Human Element of Security

This is a very good read on its own just as a story about cons, scams and social engineering. It’s basically a bunch of stories, from one of the most renowned hackers-Kevin Mitnick, explaining social engineering. It illustrates that it’s sometimes easier to persuade or influence someone to give you information, such as a password, rather than using technical hacking attacks.

Linux in a Nutshell

This is a great book for learning about how to use and configure Linux operating systems. You’ll probably need to have some Linux skills as a lot of internet facing servers happen to be Linux based.

Mobile Phone Security – Yes, phones can get viruses too...

2009-12-10T15:01:00.008+00:00

So we've already looked at WiFi security and securing your home computer, now we'll get around to something that pretty much everyone has only a few feet away from them at most times, your mobile phone. This does not offer any guarantee and accepts no liability - Its free impartial advice, because I'm nice like that !

Mobile phones are no longer just phones, they are now used as Smart Phones which can connect to the internet, use bluetooth, WiFi, email and a whole host of other services. Some are, in effect, small versions of the computers that you have sitting on your desk. In fact Apples iPhone runs a cut down version of their Mac OS. This means that as they provide more functions and services our phones become more susceptible to attack.

So what happens if my phone gets stolen?
Well there are developments being made to track mobile phones that are stolen, but generally if you have your phone stolen then you may not get it back. You could get lucky though, a thief was recently caught when he took a picture of himself on a stolen phone. He didn't realize that the phone had been programmed to send pictures to its owner's home computer ! The news story is at this link - http://www.theregister.co.uk/2009/12/04/cell_phone_pic_arrest/

This is what you can do to lessen the blow and make sure nobody runs up your bill.

Register your mobile phone at www.immobilise.com...before you lose it or it gets stolen.
This is a register of UK property and among other things you can enter mobile phone details that the police could use to find the owner of a phone, for example if they find a bag of phones in a house raid... Which is apparently becoming quite common. Amongst other things they will probably ask you for the 15-digit IMEI number. This can usually be found under the battery. Immobilise is supported by various UK Police Forces.

Use the keypad lock
Your mobile should have a PIN code to lock it after a certain amount of inactivity, maybe 5 minutes or so and also when you first switch it off & on. Your phone manual should give you details on how to set it. The default code is usually 0000 or 1234. Don't leave it as the default as they are well known. Some newer smart phone like the Android G1 use patterns on a grid instead of numbers, which does the same job.

Block your phone when its stolen or lost.
Remember that IMEI number we made a note of? Well in the event of a lost or stolen phone you should call your network provider and ask them to block the phone across all networks. They'll need the IMEI to do this effectively. The phone will be useless unless to anyone else. If you get the phone back you should be able to get it unblocked.

Block Premium Rate Numbers
Ask you service provider to block your number from calling premium rate numbers. If you don't call premium numbers or use premium text numbers for voting on TV shows etc. then get them blocked. This also helps protect against scams that persuade you to call a premium number. A common one these days is a card through your door asking you to call a number to get a parcel re-delivered. As soon as you dial the number you are charged. Sometimes up to £10.

Ok so hopefully you haven't lost your phone so you'll just want to use it in a secure manner! Mobile phones are susceptible to attacks from viruses and other nasties.

Viruses
There have been and continue to be viruses that are infecting mobile devices such as mobile phones, smart phones and PDAs. The Cabir mobile phone virus was one of the first phone viruses ever detected and was released in 2004, it infected phones running Symbian OS and included Nokia phones of the time.
Since then there have been other viruses such as "Curse of Silence", Brador, Comwar (the first to use mms to spread), Dampig, Duts etc. The most recent highly publicized phone virus is the iPhone Duh worm, which only infects 'jailbroken' iPhones so if you haven't unlocked your iPhone then don't stress about it too much.
The general rule here is to make sure that your phone software is updated ever month by going to your phone manufacturers website and checking for updates. iPhones check for updates automatically through iTunes.

Internet, Email and Applications
Remember that emails you send or receive, sites you access on the internet or applications that send data over the internet could be intercepted. Particularly if your phone is connected to a public WiFi hotspot and your not using encryption. See my blog below on WiFi Security for more information. If you are using email on your phone then use SSL/TLS options if possible. More information on setting up SSL/TLS on email should be in your phone manual.

Bluetooth
Bluetooth is used to connect devices wirelessly over a short distance of up to about 30 feet. There are three main attacks on bluetooth described below.

Bluejacking
This is the sending of unsolicited messages over Bluetooth. A Bluejacker sends out messages anonymously to other bluetooth devices like your phone.
The messages are short but can sometimes be very threatening or intimidating because of their anonymous nature. Sending such messages could be a criminal act under the Public Order Act in the UK, but I'm no lawyer so if you've been harassed via bluetooth then speak to the police about it.

Bluesnarfing
This is when someone connects to your phone and reads your text messages, and contacts etc. It is also possible to make phone calls, send and receive texts listen to phone conversations connect to the Internet etc.
Bluesnarfing is not as popular as bluejacking as it requires more expertise and software. There are however, without a doubt, many people bluesnarfing out there somewhere. It is mostly only older mobile phones that are susceptible to Bluesnarfing.

Bluebugging
Bluebugging has the same effects as Bluesnarfing and is more likely to work on newer mobile phones. Bluebugging exploits security holes in the phone software to make calls and read texts etc.

What you can do to stop bluetooth attacks
Make sure you phone is set to “Non-Discoverable” mode when your not using bluetooth. Switch bluetooth off completely if possible.
If you can, use as strong a password or as long a PIN code as possible.
More information on bluetooth can be found at - http://www.bluetomorrow.com/

Feel free to leave a comment. If you'd like me to cover something specific then let me know via a comment.

Securing Your Home Computer – Antivirus, Firewalls... What do I need & why?

2009-12-09T14:59:00.001+00:00

Today we'll look at keeping your computer as secure as possible.
We've already looked briefly at securing your WiFi connection to the internet, so now we need to know how to secure the devices that are connected to it. These devices will typically be computers, games consoles and mobile phones. This does not offer any guarantee and accepts no liability - Its free impartial advice, because I'm nice like that !

Software
The operating system is basically what makes the computer do what you want to do, such as store files on your hard drive. In addition to the operating system there are applications, or programs, that run 'on-top' of the operating system and provide a specific function such as word processing or internet browsing.
Examples of common operating systems are Windows, Linux, Mac OS X. With the exception of some Net-Books and techies, most people generally use Windows so that's what we'll look at here. What you really need to understand is that Hackers routinely find a way to exploit vulnerabilities in the software, the software is then fixed and a security update or patch is then released to fix your software on your computer, the cycle then continues the next month.

Use a Supported Version of Windows
Microsoft only updates supported versions of their software. If you use Windows NT, 95, 98 or ME which are not supported, then you are not going to be able to get the required updates and the operating system is probably full of gaping security holes. I'd advise upgrading to a current supported version of windows. Windows 2000 and XP have extended support until 13th July 2010, which isn't that far away so, again, you want to look at maybe upgrading soon. The current version is Windows 7.

Keep Up to Date
Microsoft releases security updates on the second Tuesday of each month, this is known as patch Tuesday. You can periodically go to http://windowsupdate.microsoft.com to download the updates but ideally you want to configure it for Automatic Updates so your computer does it all for you, this link should help you configure it for your particular version of windows - http://www.microsoft.com/windows/downloads/windowsupdate/automaticupdate.mspx
You also need to keep your other software & applications updated. To do this open the application / program and click 'Help' and then 'Check for updates' that should do the job with most Windows software.

Create Different Profiles for Different Users
Some default installations of Windows automatically log you on without needing to type a username or password. This method will probably also log you in with 'Administrator' privileges which means that you, or anything you click on, could potentially be able to change the way things are working on your computer... Which is a bad idea... It's best to create a separate user for yourself and make sure its not set as an Administrator. Remember to make sure that you can login as Administrator or yourself as you may need to use the Administrator and password to install new applications etc. This can protect against some viruses that are not picked up by your antivirus software.
This link tells you about configuring users on Windows XP - http://support.microsoft.com/kb/279783

Use a Strong Password
Hackers have a variety of tools to try vast amounts of passwords very quickly. There are lists freely available on the internet that include for example girls names, boys names, English dictionary, Spanish dictionary, movie titles, singers, songs etc. Pretty much anything you can think of there is a list already written that can be downloaded and plugged into a password cracking program that will automatically try all the words. There are a number of different ways to create a stronger password while still being able to remember it. One of my favorites is to take a rhyme, song line or sentence and take the first letter of each line to use as your password. For example: Mary had a little lamb its fleece was white as snow = Mhallifwwas. You should also use numbers and uppercase letters in your password.
You can test the strength of your password with this link. - http://www.microsoft.com/protect/fraud/passwords/checker.aspx

Use Antivirus Software
Antivirus software is used to prevent, detect, and remove malware, including computer viruses, worms, and trojan horses etc. Such programs may also prevent and remove adware, spyware, and other forms of malware. You can download free antivirus software for Windows systems, Two of the most popular are:
Avast Antivirus - http://www.avast.com/eng/avast_4_home.html
AVG Antivirus- http://free.avg.com/gb-en/download-avg-anti-virus-free-edition
Make sure that you comply with any license agreements.

Use a Firewall
A firewall can help prevent hackers or malicious software (such as worms) from gaining access to your computer through a network or the Internet. Windows comes with one built in but you may need to switch it on if its not already active. Some details about windows firewall on XP can be found here - http://www.microsoft.com/windowsxp/using/networking/security/winfirewall.mspx

Be Careful What You Download and Install
Viruses and other nasties are often hiding within illegal copied software, bogus video codecs and in fake antivirus software which usually warns that you have a virus and asks you to download software to cure it, the software you download, ironically, has a virus hiding within it. So as a general rule, don't click on anything that your not sure about. I'll cover internet threats more closely in the future as its a big subject !

Feel free to leave a comment. Let me know if you'd like me to cover anything specific and I'll see what I can do.

WiFi - Do you want your neighbors to see what your doing?!

2009-12-07T20:38:00.001+00:00

Wireless routers are very common and allow you to connect your laptop, mobile phones and various other devices to your internet connection. Wireless networking (WiFi) works using a radio signal which means that anyone can 'tune in' and listen to the data, such as your email, traveling across the airwaves.
Most home WiFi routers have a range of up to about 120 feet, so the signal could easily reach as far as your neighbours and the street outside your house. This means that unless you have encryption and a password on your wireless internet connection ANYONE could potentially be watching your every move on-line without you ever knowing about it.

Websites often transmit passwords or cookies unencrypted, which could give an attacker an easy way to log in to sites such as Facebook as you. In addition to snooping on you, someone could use your internet connection to download illegal or copyrighted material. If the cops come knocking on your door, its going to be you they blame. This link provides some examples :
http://news.bbc.co.uk/1/hi/technology/8381097.stm
Be aware that public WiFi hotspots are also susceptible to these kind of problems. Okay, now that I've scared you a bit you'll want to know what you can do to stop this from happening !

Essential
1.) Router Password & Encryption - Never leave your internet connection open for anyone to use. If your router has an option to use WPA encryption with a password then that is what you should use. Some routers are now being delivered already setup with a random password such as QYANE2OR using WPA encryption. If your router does not allow WPA encryption then go for WEP encryption, but be aware that WEP encryption can be easily cracked in less than 15 minutes in some cases.

2.)If you are choosing a password yourself then make sure it is as long as is allowed and is not easily guessable. You should also avoid common words and names such as movie titles or film stars names.

3.) If you are using a public hotspot then exercise caution with what you access on the internet. This is a whole other area that I'll cover in detail at a later date.

Advanced
1.) Hide the routers Name - The SSID is the name of your Router, for example "Nicks internet" that shows up when you look for wifi networks to connect to. If you hide it then others can only connect to it if they already know the name and connect manually. It won't show up when anyone looks for a wifi network.

2.) Restrict access to your router & internet connection - You can restrict access to your router and allow only your laptop, phone etc to connect to it. Every device that can connect to a network has its own unique code assigned to it known as a "MAC Address". You can set your router to only allow those MAC addresses to use your internet connection.

Your router user guide or manual should give you details of how to configure additional options.

If you'd like to know more about how to configure your wifi router with these extra security options, or the hazards of public hotspots, then feel free to leave a comment asking for more info and I'll see what I can do !