It is extremely easy to extract the text that is stored in the clipboard to steal your sensitive information. The copied data can be easily accessible over the net by JavaScript or ASP or combination of both.
Here is the JavaScript code for retrieving clipboard text to a webpage:
To avoid this do as below:
1) Go to ‘Control Panel’. One way to access it is by typing control in Run 
2) Go to internet option and select security tab
3) press custom level
4) In the security settings, select disable option under
“Allow paste operation via script” and click OK
That’s it!! Now your sensitive information is safe from hackers.