What is CAPTCHA and How it Works?

CAPTCHA or Captcha (pronounced as cap-ch-uh) which stands for “Completely Automated Public Turing test to tell Computers and Humans Apart” is a type of challenge-response test to ensure that the response is only generated by humans and not by a computer. In simple words, CAPTCHA is the word verification test that you will come across the end of a sign-up form while signing up for Gmail or Yahoo account. The following image shows the typical samples of CAPTCHA.

 

 

Almost every Internet user will have an experience of CAPTCHA in their daily Internet usage, but only a few are aware of what it is and why they are used. So in this post you will find a detailed information on how CAPTCHA works and why they are used.

 

What Purpose does CAPTCHA Exactly Serve?

CAPTCPA is mainly used to prevent automated software (bots) from performing actions on behalf of actual humans. For example while signing up for a new email account, you will come across a CAPTCHA at the end of the sign-up form so as to ensure that the form is filled out only by a legitimate human and not by any of the automated software or a computer bot. The main goal of CAPTCHA is to put forth a test which is simple and straight forward for any human to answer but for a computer, it is almost impossible to solve.

 

What is the Need to Create a Test that Can Tell Computers and Humans Apart?

For many the CAPTCHA may seem to be silly and annoying, but in fact it has the ability to protect systems from malicious attacks where people try to game the system. Attackers can make use of automated softwares to generate a huge quantity of requests thereby causing a high load on the target server which would degrade the quality of service of a given system, whether due to abuse or resource expenditure. This can affect millions of legitimate users and their requests. CAPTCHAs can be deployed to protect systems that are vulnerable to email spam, such as the services from Gmail, Yahoo and Hotmail.

 

Who Uses CAPTCHA?

CAPTCHAs are mainly used by websites that offer services like online polls and registration forms. For example, Web-based email services like Gmail, Yahoo and Hotmail offer free email accounts for their users. However upon each sign-up process, CAPTCHAs are used to prevent spammers from using a bot to generate hundreds of spam mail accounts.

 

Designing a CAPTCHA System

CAPTCHAs are designed on the fact that computers lack the ability that human beings have when it comes to processing visual data. It is more easily possible for humans to look at an image and pick out the patterns than a computer. This is because computers lack the real intelligence that humans have by default. CAPTCHAs are implemented by presenting users with an image which contains distorted or randomly stretched characters which only humans should be able to identify. Sometimes characters are striked out or presented with a noisy background to make it even more harder for computers to figure out the patterns.

Most, but not all, CAPTCHAs rely on a visual test. Some Websites implement a totally different CAPTCHA system to tell humans and computers apart. For example, a user is presented with 4 images in which 3 contains picture of animals and one contain a flower. The user is asked to select only those images which contain animals in them. This Turing test can easily be solved by any human, but almost impossible for a computer. 

 

Breaking the CAPTCHA

The challenge in breaking the CAPTCHA lies in real hard task of teaching a computer how to process information in a way similar to how humans think. Algorithms with artificial intelligence (AI) will have to be designed in order to make the computer think like humans when it comes to recognizing the patterns in images. However there is no universal algorithm that could pass through and break any CAPTCHA system and hence each CAPTCHA algorithm must have to be tackled individually. It might not work 100 percent of the time, but it can work often enough to be worthwhile to spammers.

How to Identify and Avoid Phishing Scams

Phishing is a form of social engineering technique used by hackers to gather sensitive information such as usernames, passwords and credit card details by posing as a trustworty person/organization. Since most online users are unaware of the techniques used in carrying out a phishing attack, they often fall victims and hence, phishing can be very effective.

With the dramatic increase in the number of phishing scams in the recent years, there has also been a steady rise in the number of people being victimized. Lack of awareness among the people is the prime reason behind such attacks. This article will try to create awareness and educate the users about such online scams and frauds.

Phishing scams usually sends an email message to users requesting for their personal information, or redirects them to a website where they are required to enter thier personal information. Here are some of the tips that can be used to identify various phishing techniques and stay away from it.

 

Identifying a Phishing Scam

 

1. Beware of emails that demand for an urgent response from your side. Some of the examples are:

• You may receive an email which appears to have come from your bank or financial organization stating that “your bank account is limited due to an unauthorized activity. Please verify your account asap so as to avoid permanant suspension”. In most cases, you are requested to follow a link (URL) that takes you to spoofed webpage (similar to your bank website) and enter your login details over there.
• In some cases, phishing emails may ask you to make a phone call. There may be a person or an audio response waiting on the other side of the phone to take away your credit cards details, account number, social security number or other valuable data.

2. Phishing emails are generally not personalized. Since they target a lagre number of online users, they usually use generalized texts like “Dear valued customer”, “Dear Paypal user” etc. to address you. However, some phishing emails can be an exception to this rule.

3. When you click on the links contained in a phishing email, you will most likely be taken to a spoofed webpage with official logos and information that looks exactly same as that of the original webpages of your bank or financial organization. Pay attention to the URL of a website before you enter any of your personal information over there. Even though malicious websites look identical to the legitimate site, it often uses a different domain or variation in the spelling. For example, instead of paypal.com, a phishing website may use different addresses such as:

• papyal.com
• paypal.org
• verify-paypal.com
• xyz.com/paypal/verify-account/

 

Tips to Avoid Being a Victim of Phishing

 

1. Do not respond to suspicious emails that ask you to give your personal information. If you are unsure whether an email request is legitimate, verify the same by calling the respective bank/company. Always use the telephone numbers printed on your bank records or statements and not those mentioned in the suspicious email.

2. Don’t use the links in an email, instant messenger or chat conversation to enter a website. Instead, always type the URL of the website on your browser’s address bar to get into a website.

3. Legitimate websites always use a secure connection (https://) on those pages which are intended to gather sensitive data such as usernames and passwords, account numbers or credic card details. You will see a lock icon in your browser’s address bar which indicates a secure connection. On some websites like paypal.com which uses an extended validation certificate, the address bar turns GREEN

PASSWORD PROTECT YOUR WORD FILES

We all use Microsoft Word to create documents.
and some times we dont want other people to access our documents
specially when you are on a shared computer in your company and you may have your certain secret data stored in your word document that should not be accessed by your boss or other employee’s.

To deal with such a situation Microsoft word 2007 integrated a security feature in Microsoft word so that you can password protect your files.


just follow these simple steps to make your document protected


Click on the Microsoft Office Button present on the top left corner of the window.
Now Click on the Save As option
Now a new window will pop up.
Click on Tools option at the bottom of the window.
Now you will have two options.
You can select either one or both options
One is Password To Open it will ask for the password every time the document is opened.
So to view the document you have to enter the password first.
Second is Password To Modify it will ask for the password every time somebody tries to modify the document.

Difference Between Virus,Worms,Trojan and Spyware

Virus:-A virus is a self replicating program that attaches itself to an executable file.When  the file is executed the virus automatically gets executed and enters into system memory .Once it enters into system memory it either searches for other files that can be infected or stays in the background and infect the files that are uses the virus infected program.
Worms:Worms are very similar to viruses but differ in way that they donot bind themselves to executable files instead  to replicate themselves they uses the network.If you find excessive use of your network bandwidth then you may be infected by a worm.So,a worm donot require a user to execute any file for its execution it can work without user intervention.
Trojan Horse:-A trojan horse is harmful program which may seem harmless to the user before its installation but instead it is programmed or reverse engineered to  facilitate unauthorised remote access to the computer.Trojan’s donot replicate themselves.
Spyware:-A spyware is a program that secretly monitors and collects pieces of information.They usually run in stealth mode and cannot be detected easily.Keyloggers is a great example of spyware software.There are not limited to just spying but can also send data to remote computers