Hacker 10 – Security Hacker – Page 48

How to encrypt and clear Windows page file

When you are operate your computer the files you are managing will be temporarily stored in volatile RAM memory, once you close the files you are working on the occupied RAM memory will clear itself and be available again.

Computer’s RAM memory (all computers have it) can run out, when this happens Windows will use what it is known as Windows page or swap file. This file is an internal Windows operating system file where temporary data is stored for the operating system to have quick read and write access.

Using the page file has two implications, one is that it slows down your computer because the data is being read from the hard disk (slower than RAM memory) and two is that data written to the Windows page file can be recovered via specialist software, data stored in the Windows page file can include passwords and all kind of personal files, but if Windows did not have any page file and you exhausted your RAM memory, the computer would crash.

How to locate and resize pagefile.sys

Windows swap memory filename is pagefile.sys it is not visible to users and hard to locate, you can increase or decrease Windows default page file size or stop using it through Windows control panel, you might need to do this depending on how much RAM memory your computer has installed and how much you use, a bigger page file is suitable for those low on RAM and setting a smaller page file size will give you hard disk space back.

In Windows Vista go to the Start Windows logo>Control Panel>System and Maintenance>System

Where it says “Computer name, domain and workgroup settings” click on Settings, a new window will open asking you for administrator rights, on the new window click on the Advanced tab, right below where it says Perfomance click on Settings click on Advanced you will say that it says “Virtual memory and total paging file size for all drives” that is where you can change Windows page file size or instruct Windows not to use a page file at all.

If you choose not to use a page file when your RAM memory runs out Windows will crash, if you have a high amount of RAM, like 8GB and do not run virtual memory intensive applications like high end games and graphic editors, you should never run out of RAM and it is safe to disable the Windows page file.

How to encrypt Windows page file

Your Windows operating system comes with a program installed called fsutil you can access it using Windows cmd command line, it is very important that you run Windows cmd as administrator, otherwise you won’t be able to encrypt the Windows page file.

To run cmd as an administrator go to Start Windows logo>All programs>Accessories>Command prompt (right click on it and choose “Run as administrator“) Windows command line black window will open.

To encrypt Windows page file type:

fsutil behavior set EncryptPagingFile 1

Before encryption takes place your computer needs to be rebooted.

To check if Windows page file is encrypted type:

fsutil behavior query EncryptPagingFile

The value 1 indicates that the page file is encrypted, a value of 0 indicates that it is not.

If something doesn’t work or you change your mind you can decrypt Windows page file typing:

fsutil behavior set EncryptPagingFile 0

When you encrypt Windows page file built-in Windows EFS (Encrypting File System) is used, the needed encryption keys are created and erased by Windows as needed, this only works in hard disks formatted with the NTFS file system (not FAT).

How to clear Windows page file

You can tell Windows to erase its virtual memory, aka page file, every time you shut down the computer, but be aware that this will slightly slow down the shutdown process.

To automatically clear Windows page file contents on shut down invoke the registry editor, go to Windows Run using the Windows key on your keyboard +R, alternatively go to Start>All Programs>Accessories>Run, type regedit click enter and the Windows registry will open in a new window.

Navigate to: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session
Manager\

You will see a DWORD value “ClearPageFileAtShutdown”, double-click on it and change value data from “0” to “1″, if you want to reverse the changes later on change the value back to “0“.

Securely erasing the page file contents can only be done using specialist privacy data wiping software that will overwrite its contents, the system above will clear the page file contents but they will still be recoverable until the page file has been used, and overwritten, again.

25 April, 2011

How does encryption work? Encryption for dummies

In the online world encryption disguises data rearranging the data bits so that nobody can read or see the information without the secret key, this key can consist of a password or a digital file, aka keyfile, encryption secures plain text as well as any other digital media like photos, videos or software, you can also encrypt a whole operating system and a partition.

To secure data, encryption uses mathematic functions known as cryptography algorithms, aka ciphers, some example of well known and trusted cryptography algorithms are AES, Blowfish, Twofish and Serpent, these ciphers can be subcategorized with a number indicating its strength in bits.

An encryption algorithm key length indicates its size measured in bits, the length indicating the algorithm strength in bits will always be even (bit is binary unit composed of zeros and ones), these keys are used to control the operation of a cipher.

The more mathematical strength the encryption algorithm has the more difficult it will be to crack it without access to the key but a strong cipher normally requires more computational power, a few seconds of wait might not matter much to the home user but for businesses dealing with thousands of calculations each hour to decrypt/encrypt data in their servers it will mean that more money has to be spent in hardware and electricity.

Why not all websites use encrypted SSL connections

If all of the websites on the Internet used encrypted SSL connections the servers serving content using SSL (Secure Socker Layer) would need more CPU power and more electricity, when you multiply this by millions of pages served each second, costs dramatically add up, page loading would also be slower because the decryption process needs to take place in the computer and those using very low end processors in mobile devices would suffer speed the most.

When choosing an encryption algorithm it is important to look at is many factors, not only key size, when it comes to security how an algorithm has been implemented is much more important than key length, algorithm perfomance also matters, if people had to wait an hour to encrypt and decrypt files encryption would become unusable, a trade off in between security and usability needs to be established, the best is to always choose a standard algorithm that has been widely scrutinised by experts, aka cryptographers.

What encryption key length should I choose?

An AES 128-bit encryption key is considered very strong and suitable to withstand future attaks, the U.S. Government requires 192 or 256-bit AES encryption keys for highly sensitive data, AES is the standard US Government encryption algorithm for data encryption.

A 128-bit key, can have more than 300,000,000,000,000,000,000,000,000,000,000,000 key combinations.

The importance of choosing a strong password for encryption

Encryption software gathers random data before encrypting your files, aka entropy, the password you use will be part of this random data gathered to cipher the files, hence why it is very important that you choose a long passphrase, in addition, you should not use any dictionary words to thwart brute force attacks.

A brute force attack consists of an automatic process where all of the dictionary words are quickly whirled at the password login prompt, as computers have become increasingly faster this can be done in a matter of hours or less using cloud computing.

Encryption security tips

Always choose an encryption program that uses a standard cipher that has been scrutinised by experts, e.g AES

Do not use dictionary words as your password, use a long passphrase made up of capital and small letters with punctuation signs and numbers

Do not use the passphrase you use to encrypt your data for anything else like your webmail password or an online forum which security can be compromised

Never trust a third party service to store your encryption keys or carry out the encryption implementation, if you store data online encrypt it yourself in your computer

Watch out for keyloggers and malware in your computer that could capture your keystrokes and your secret passphrase, use an updated antivirus and firewall

Never reveal to anyone your password, not even to a support department whose staff could be outsourced in a crime ridden country or could be impersonating someone else

Encryption links for beginners

National Cryptologic Museum Foundation

NSA Cryptokids

Intypedia Information Security

Bruce Schneier’s blog (Cryptographer)

23 April, 2011

Review Axcrypt free file encryption program

AxCrypt is a free open source encryption program for Windows computers available in 32-bit and 64-bit versions, after installing AxCrypt it will integrate with your right-click menu and allow for single click encryption, it is very easy to use, there is nothing to configure, everything works straight out of the box after installation, you can right-click on a folder and instruct AxCrypt to encrypt the entire contents, the program will then create multiple encrypted file belonging to each one of the files inside.

The software interface is multilingual, available in 7 different languages, it can be used from the command line and a portable version of AxCrypt is available for those on the go wanting an encryption programs that runs from inside a USB thumbdrive.

There is no maximum file size for encryption, the only size limit comes imposed by your operating system boundaries on file size, AxCrypt runs on very low resources, to use AxCrypt you only need 5MB RAM, 2MB hard disk space, temporary disk space 1.5 the size of the file being encrypted, and a low end computer desktop CPU.

Because AxCrypt is open source, you can download the source code and compile the program yourself where you to feel inclined, you could check the source code for backdoors before compiling it.

AxCrypt encryption method

AxCrypt uses the AES algorithm with 128-bit keys for file encryption and SHA-1 for hashes, there is no backdoor, if you forget your password that is it. The AES encryption algorithm that AxCrypt uses was selected by NIST (American Nations Institute of Standards and Technology) after a 5 year process in which fifteen competing designs were presented, AES is the current Federal USA Government standard algorithm for encryption.

Files encrypted with AxCrypt have the extension .axx, it retains the original file name and information, you can rename the file if you want to disguise a descriptive name, temporary files are automatically shred, the encryption keys are not stored in Windows page file. If you don’t want to erase the file after encryption you can just choose encrypt copy from AxCrypt menu.

To make it more difficult for an attacker to brute force your password and make the best of the full 128-bit encryption strength potential that AxCrypt offers, you should be using with a meaningless passphrase sequence of 22 characters, if you decide to create a keyfile with AxCrypt and use it for encryption your files will automatically be secured at the maximum level, the keyfile encryption method can be used in conjunction with a password.

AxCrypt software developers recommend that you always create a keyfile for encryption, the created keyfiles are made of 256 bits encoded in Base64, they are saved as a .txt text file with random characters in it.

AxCrypt file decryption

When sending your encrypted file over email to someone else that person will need AxCrypt installed to decrypt it, there is a free program called AxDecrypt that allows others to view AxCrypt encrypted files without installing the full software, AxDecrypt only serves to open files with the .axx extension and it can not encrypt.

You can choose to create .exe self-decrypting files, the other end does not need any kind of program to view the encrypted data, they just need to know the password used, one downside is that .exe files many times contain viruses and few people trust them, antivirus could flag them as a malware, and some email services like Gmail do not accept the sending of .exe file attachments.

Like all symmetric encryption software when you send an encrypted file to someone he/she will need to know the password you are using, you can transmit the password over a secure channel, ideally in person and if that it is not possible then using an encrypted VoIP call, or an Internet messaging program with built in encryption.

File encryption vulnerabilities

While AxCrypt contains no backdoor and the algorithm it uses can not be cracked at present, all file encryption programs have side vulnerabilities residing on the operating system, this is what you should watch out for.

Weak password, file encryption programs are only as good as your password

Solution: Use a very hard to guess passphrase not contained in a dictionary or use a keyfile to secure your files, use a password manager if needed to remember it.

Temporary files and backup copies stored by the your operating system while viewing the decrypted file

Solution: Use data wiping software in conjunction with your file encryption software, routinely wipe Windows locations where temporary files are normally stored, like for example the Windows page file, quality data wiping software come already preconfigured to securely erase those locations.

Your computer has a keylogger installed that captures your password

Solution: Have an updated antivirus and use a high quality firewall that will warn you of outgoing connections, the default Windows firewall will not do this.

After decrypting a file AxCrypt will automatically overwrite it, secure data wiping consists of a single pass using pseudorandom data, this is enough to protect you from common undelete software but it will not protect you from expensive special diagnostics hardware used by well funded adversaries like corporations and law enforcement, if you need that level of protection get a different encryption software because data could be recovered from previously erased data.

AxCrypt online documentation is very complete, if you want to know the inner workings visit their homepage, if you get stuck, they have an online forum and a mailing list where to ask questions to other users.

Conclusion on AxCrypt file encryption

It doesn’t have the prettiest of interfaces and its configuration capabilities are next to none, while some might view this as a disadvantage, others will see it as an advantage because it makes operation very easy to understand for beginners.

AxCrypt strong points are that it is open source, it contains no backdoor, it uses a standard uncrackable algorithm for encryption (AES128) and it is easy to operate, its interface could be improved but it gets the job done, this is an excellent program for those on a budget because it is free (donationware) and it will securely encrypt your files.

I would not hesitate recommending AxCrypt to friends in need of secure encryption software but the single pass temporary data overwriting was disappointing, if you are a business user stay out of AxCrypt because it is only secure enough for the home user due to this.

Visit AxCrypt homepage

21 April, 2011

Anonymous web surfing with The Amnesic Incognito Live System

Tails, short for The Amnesic Incognito Live System, has Ad-block preinstalled on its Iceweasel (Firefox based) browser, it comes with many other privacy enhancing tools to stop companies and repressive Governments tracking down Internet users.

This Debian based Linux live CD enables you to hide your IP address while surfing the Internet, it comes preconfigured to use the anonymous tor network for all outgoing connections, this will hide your IP at all times, you do not need to know anything about Linux to use it, just download the ISO file burn it to a CD, reboot your computer, MAC or PC, and it will work straight out of the box.

Anonymous live CD features

Supports mobile broadband devices like 3G USB dongles
Can be booted up from a USB thumbdrive instead of a live CD
Multilingual support including Arabic, Chinese and Spanish in between other languages
Firewall drops incoming packets by default
Instant Messenger Pidgin comes with the OTF messaging plugin to proxy communications through tor
Internet browser comes with the HTTPS Everywhere, FireGPG and Ad-block extensions
Stops cold boot attacks by wiping RAM memory on shutdown
Virtual keyboard available to stop keyloggers
Support for i2p eepsites, hidden websites hosted anonymously
Email client ClawsMail comes with GnuPG support to encrypt email messages

Live CD with encryption & file deletion

The Amnesic Incognito Live System includes secure-delete integrated on its file manager, a program to wipe free disk space and sensitive files, a front end encryption key manager called SeaHorse will take care of digital signatures and GPG encryption keys.

If you are comfortable with Linux command line you can take advantage of cryptsetup to encrypt files and macchanger to change your computer MAC address. Those are only the security features, open source everyday software for production purposes includes OpenOffice.org to edit documents, The Gimp to edit photos, Audacity to edit sound files and many others.

This operating system to hide your IP address has two preconfigured users: amnesia and root, the password is the same for both of them, amnesia.

Visit The Amnesic Incognito Live System

18 April, 2011

3 ways to encrypt your VoIP calls

VoIP calls are transmitted over the Internet unencrypted, the data packets can easily be intercepted by a malicious hacker to record the calls and listening in, a simple packet sniffer like WireShark is all that it is needed to eavesdrop on a VoIP call, no high skills are involved.

How to encrypt VoIP calls

Use Zfone to add encryption to your VoIP client: Zfone works on top of your unencrypted VoiP software watching for VoiP data packets going in and out of your computer, when it finds them it ciphers the packets encrypting the VoIP call, there is also a man-in-the-middle (MiTM) attack countermeasure by displaying a short authentication string for the user to verbally compare over the phone witht the other end, Zfone is open source software using the ZRTP protocol, there are no backdoors of any kind included.Before considering Zfone to secure your VoIP calls have into account that the software must be installed by both callers and Zfone does not work with Skype because Skype uses a closed source protocol not compliant with the standard VoIP protocol.
Zfone VoIP encryption software
Use a Virtual Private Network (VPN): A VPN like HMA can encrypt all of your internet traffic routing it through their encrypted OpeVPN tunnel, this will include all of your VoIP calls. Routing your VoIP calls through a VPN will slightly increase the bandwidth requirement and produce some CPU overhead.One benefit of using a VPN is that if your ISP or a corporate firewall is blocking VoIP calls using a VPN for VoIP will get around Internet filters, they won’t even know you are making a call, it will also get around state sponsored surveillance which is normally carried out at ISP level.
Wiretapping VoIP password
Use VoiP software with built in encryption: Some VoIP clients like Skype have built-in encryption used to cipher VoIP data packets, if you adopt this solution to secure your phone calls, try to choose voice over IP software compatible with as many other VoIP clients as possible using open source encryption (not Skype) this will make it much harder to introduce a backdoor and it might not require the other end to have the same VoIP client installed for encryption to work.VoIP software using encryption: PhonerLite ; TiviPhone

5 April, 2011

9 ways to protect your email address from spambots

Obfuscating your email is the best way to stop spammers bots from harvesting and storing your email address from a website, newsgroup or forum, spammers automated software follows certain patterns to identify and store an email address, they can’t comprehend it when a person has deliberately hidden his/her email address to be human readable only, they are also unable of following instructions.

Change your email syntax: Replace the @ symbol in between your username and email domain name with (at) , (AT), the . with the words DOT and add spaces in between the words, for example: hacker10 (AT) fastmail DOT com
Create a graphic image of your email address: Spambots can’t read the letters embedded in pictures like jpegs, with a graphics editor you can create a .jpeg with your email address inside it, after that you can then either upload it, if the site allows, or use a free file hosting image site and link to it, for example:
Hacker10 Email address inside graphic

To email click on link:http://www.hacker10.com/?p=10773

There are free online services that will create a graphical image of your email address in seconds you don’t even need a graphics editor.
Use email plus addressing: If your main email address is example@gmail.com you could use example+hacker10@gmail.com and all of the messages to that email address not only will still be delivered to your main email account but also classified into the folders named after the email username + symbol, plus email addresses structure goes like this:username+foldername@domain.comYou can create an unlimited number of throw away email addresses this way, not only you will be able to filter out one particular address if it receives unsolicited email, but also spot the source of the spam, if you have only used one email address for one site and nowhere else then it is clear where spammers harvested the email from.The main caveat to email plus addressing is that few free email services support this feature, Gmail and Fastmail do but with Yahoo it only works with its premium paid for email service. Another problem you might encounter using email plus addressing is that many webforms will not accept your email address because they do not recognise the + character as valid, Yahoo mail uses a – character instead, standing a better chance to be allowed inside webforms.

Use a disposable email address: There are plenty of services available providing free disposable email addresses, aka DEA, most of them will erase your email address in just a few minutes or some weeks at most, disposable email addresses do not normally use a password and others choosing the same username could read the contents, you would have to avoid its use for emails containing personal information and choose a hard to guess username.Disposable Email Services:
- Yopmail: http://www.yopmail.com/en/
- Guerrillamail:http://www.guerrillamail.com/

Use an email forwarding service: If you need a disposable email address that lasts for months choose an email forwarding service instead, you will be asked to sign up which takes longer but you know that all subsequent email messages will be forwarded to you.Mail forwarding services:
- TrashMail: https://trashmail.com
- SpamGourmet: http://spamgourmet.com/

Register a domain name and use it for email: For around $10 year you can register the domain name of your choice and use that domain as a mail forwarding address, your domain registrar will supply you with a control panel from where you can activate it for email and forward all of your messages to your real email address. Make sure to choose a domain name registrar with this facility, most of them do though.Domain registrars with email forwarding:
- NameSilo:https://www.namesilo.com/
- Register.eu:http://www.register.eu/

Use RecaptCha mailhide: This free service from Google will convert your email address into a clickable link and it will ask users to enter a captcha code before they can see it, a captcha code is the same antispam system many blogs use to stop spambots commenting on them.
- reCAPTCHA Mailhide: http://www.google.com/recaptcha

Choose a non obvious email addresses: Spammers use software to generate likely email username combinations. Do not use your own name or dictionary word as your main email address, it makes it harder to guess for an automated tool.If you need an easy to remember email address to give away you can use an alias email address that can be disabled if spam comes in but do not choose it as your main account email as you can not usually change it.

Use email aliases: Many email services will allow you to create a second email address directing all of the email to your main account, always use an email alias when you communicate with someone, this way if that email is compromised you can always cancel it.

14 March, 2011

How to find out your router IP address in Windows

There are many router models out there and the one that your ISP gives to you sometimes does not include the router IP address, they come with an auto installable kit instead.

Entering a router IP address into your web browser toolbar will take you to the router interface, this is very useful to change the router default settings and others.

A router IP address can not be changed, this is embedded into the hardware by the manufacturer, a router of the same brand and series will use the same IP, which means that it is not secret, anyone using the same router as you and in range, could connect wireless to your router interface and modify the settings, you should always change the default router password.

Step 1 to find router address:

Open Windows run and type cmd.exe OR command.com, alternatively, if you can’t find Windows run search for cmd.exe OR command.com

Step 2 to find router IP address:

At the Windows command line prompt type ipconfig you will now see your computer Internet IP, IPv6, MAC address and router IP address.

The router IP address is the IP written right after where it says “Default Gateway” , you can notice in the picture that there are two default gateways, this is because the router is wireless and has more than one connection port, the RJ45 ports belongs to the wired ethernet connection (in this case empty) and the other port is a default router gateway belonging to the Wireless connection.

24 February, 2011

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