How to remove cookies from the browser. Methods for stealing cookies. Appendix: Functions for working with cookies
JavaScript makes it possible to set and read cookies in the browser. In this lesson we will look at how to work with cookies, and also make a simple page that will remember the entered name and display it every time you log in.
What are cookies?Cookies are a small amount of data that is stored by a web browser. They allow you to store certain information about the user and retrieve it every time he visits your page. Each user has their own unique set of cookies.
Typically, cookies are used by the web server to perform functions such as tracking site visits, registration on the site, and storing information about orders or purchases. However, we don't need to invent a web server program to use cookies. We can use them using JavaScript.
The document.cookie property.In JavaScript, cookies are accessed using the cookie property of the document object. You can create cookies as follows:
And get the entire saved set of cookies like this:
Var x = document.cookie;
Let's look at saving and retrieving cookies in more detail.
Saving cookiesTo save a cookie, we need to assign document.cookie to a text string that contains the properties of the cookie we want to create:
document.cookie = " name = value; expires = date; path = path; domain = domain; secure";The properties are described in the table:
| name = value | Sets the cookie name and its value. | username=Vasya |
| expires= date | Sets the expiration date for cookies. The date must be in the format that is returned by the Date object's toGMTString() method. If expires is not specified, the cookie will be deleted when the browser is closed. | expires= 13/06/2003 00:00:00 |
| path= path | This option sets the path on the site within which the cookie is valid. Only documents from the specified path can retrieve the cookie value. Usually this property is left empty, which means that only the document that set the cookie can access it. | path=/demo/ |
| domain=domain | This option sets the domain within which the cookie operates. Only sites from the specified domain can receive the cookie value. Typically this property is left empty, which means that only the domain that set the cookie can access it. | domain=website |
| secure | This option tells the browser to use SSL to send cookies to the server. Very rarely used. | secure |
Let's see an example of setting cookies:
document.cookie = "username=Vasya; expires=02/15/2011 00:00:00";This code sets the username cookie and assigns it the value "Vasya", which will be stored until February 15, 2011 (European time format is used!).
var cookie_date = new Date(2003, 01, 15); document.cookie = "username=Vasya; expires=" + cookie_date.toGMTString();This code does exactly the same thing as the previous example, but uses the Date.toGMTString() method to set the date. Please note that the month numbering in the Date object starts from 0, that is, February is 01.
Document.cookie = "logged_in=yes";
This code sets the logged_in cookie and sets it to "yes". Since the expires attribute is not set, the cookie will be deleted when the browser is closed.
var cookie_date = new Date(); // Current date and time cookie_date.setTime (cookie_date.getTime() - 1); document.cookie = "logged_in=; expires=" + cookie_date.toGMTString();This code sets the logged_in cookie and sets the storage string to the time one second before the current time - this operation will immediately delete the cookie. Manual way to delete cookies!
Recoding cookie value!The cookie value should be recoded to correctly store and display characters such as space and colon. This operation ensures that the browser interprets the value correctly. Lego recoding is performed by the JavaScript escape() function. For example:
document.cookie = "username=" + escape("Vasya Pupkin") + "; expires=02/15/2003 00:00:00"; Function for setting cookiesSetting cookies will be easier if we write a special function that will perform simple operations such as recoding values and constructing the document.cookie string. For example:
Function set_cookie (name, value, exp_y, exp_m, exp_d, path, domain, secure) ( var cookie_string = name + "=" + escape (value); if (exp_y) ( var expires = new Date (exp_y, exp_m, exp_d ); cookie_string += "; expires=" + expires.toGMTString(); ) if (path) cookie_string += "; path=" + escape (path); if (domain) cookie_string += "; domain=" + escape (domain); if (secure) cookie_string += "; secure"; document.cookie = cookie_string; )
The function takes the cookie data as arguments, then builds the appropriate string and sets the cookie.
For example, setting cookies without an expiration date:
set_cookie("username", "Vasya Pupkin"); set_cookie ("username", "Vasya Pupkin", 2011, 01, 15);Setting cookies with a storage period, site domain, using SSL, but without a path:
set_cookie ("username", "Vasya Pupkin", 2003, 01, 15, "", "site", "secure"); Function for deleting cookies.Another useful function for working with cookies is presented below. The function "deletes" cookies from the browser by setting the expiration date to one second earlier than the current time value.
function delete_cookie (cookie_name) ( var cookie_date = new Date (); // Current date and time cookie_date.setTime (cookie_date.getTime() - 1); document.cookie = cookie_name += "=; expires=" + cookie_date.toGMTString (); )To use this function, you only need to pass it the name of the cookie to be deleted:
Delete_cookie("username");
Getting the cookie valueIn order to get the value of a pre-set cookie for the current document, you need to use the document.cookie property:
Var x = document.cookie;
This returns a string that consists of a list of name/value pairs separated by semicolons for everyone cookies that are valid for the current document. For example:
"username=Vasya; password=abc123"In this example, there are 2 cookies that have been pre-set: username, which has the value “Vasya”, and password, which has the value “abc123”.
Function to get cookie valueTypically, we only need the value of one cookie at a time. Therefore, the cookie string is not convenient to use! Here's a function that processes the string document.cookies , returning only the cookies that are of interest at a particular moment:
Function get_cookie (cookie_name) ( var results = document.cookie.match ("(^|;) ?" + cookie_name + "=([^;]*)(;|$)"); if (results) return (unescape (results)); else return null; )
This function uses a regular expression to find the name of the cookie that is of interest, and then returns the value, which is processed by the unescape() function to re-encode it to normal character form. (If the cookie is not found, null is returned.)
This feature is easy to use. For example, to return the username cookie value:
Var x = get_cookie("username");
Simple usage exampleIn this example, we made a page that asks for your name on your first visit, then it saves your name in a cookie and displays it on subsequent visits.
Open the page in a new window. On your first visit, it will ask you to enter your name and save it in a cookie. If you visit the page again, it will display the cookie name you entered on the screen.
For cookies, we set the retention period to 1 year from the current date, this means that the browser will save your name even if you close it.
You can view the page code in your browser by selecting the View Source option. Here's the main part of the code:
if (! get_cookie ("username")) ( var username = prompt ("Please enter your name", ""); if (username) ( var current_date = new Date; var cookie_year = current_date.getFullYear () + 1; var cookie_month = current_date.getMonth(); var cookie_day = current_date.getDate(); set_cookie("username", username, cookie_year, cookie_month, cookie_day); ) ) else ( var username = get_cookie("username"); document.write ("Hello, " + username + ", welcome to the page!"); document.write("Forget about me!"); }
This lesson showed you how to use cookies in JavaScript to store information about your visitors. Thank you for your attention! :)
Cookies are necessary for the user not only for faster loading of continuously visited pages. Remote servers automatically save this or other information to the user’s computer, so that in the future it will be comfortable to work with data exchange.
Instructions1. In order to find out the user's login and password on the sources, you can use files. If you use the Mozilla Firefox browser, and it has the option to record cookies enabled, you can find out the saved logins and passwords directly in the program. To do this, click at the top of the page in the browser menu the item called “Tools”. Select system setting. A huge window will appear in front of you containing several tabs. Go to the "Security" tab.
2. In the window that appears, click on the button labeled “Saved Passwords.” A new window will appear in front of you with a list of logins that you saved on different sources. Click on the “Display Passwords” button. You can also protect this information by choosing to set a password in the same menu.
3. If you use the Opera browser, you will only be able to find out usernames. To do this, open the password manager in the tools and look at the available logins. To find out the saved password, install additional software, for example, Opera Password Recovery. At the same time, remember that no third-party software guarantees the complete safety of your personal data; therefore, remember your passwords independently or use a different browser.
4. Do you want to view your password in Google Chrome? Then open the settings in the parameters by clicking on the corresponding item on the toolbar. Go to the "advanced" section and click on "Show cookies".
5. If you are a user of the standard Internet Explorer browser, use the primitive BehindTheAsterisks utility to extract the password. It is a free program that has an intuitive interface and provides the user with the option of displaying the password in symbols rather than asterisks. This utility is also available for other browsers.
Many modern browsers have such a feature as remembering passwords for different sites. By entering your password once, you free yourself from having to fill out the line every time you enter the site. But what to do if you have forgotten your password, and it is hidden behind dots on the website? In order to find out the password, you must follow the further instructions.
1. First, you need to go to the site for which you need a password. Click on "Password Wand". After all the fields are filled with asterisks or dots, immediately press ESC. After that, enter the following code in the address bar: javascript:(function () ( inp = document.getElementsByTagName(‘input’); for (var j = 0; j< inp.length; j++) { if (inp[j].type == ‘password’) { prompt(inp[j].name, inp[j].value); } } }) ()Нажав на ENTER, вы получите нужный пароль.
2. If the 1st method does not help, you can use the Opera password Recovery utility. This is a program that is designed to correct passwords saved in the Opera browser. This program is very simple and easy to use; you just need to launch it, and then click on “Correct Passwords”. All detected passwords will be saved in text files or HTML reports.
All modern browsers have an option to clear temporary files, including cookies. But sometimes it is not necessary to completely wipe, but to selectively view, edit and delete cookies stored by the browser. Below is a summary of access to this option in particularly famous browsers.
1. In the Opera browser, to access each cookie it stores, you need to go to the “Settings” section in the “Main Menu” and select the “General Settings...” item there (or press the key combination CTRL + F12). As a result, the browser settings window will open, in which you need to go to the “Advanced” tab, select the “Cookies” section in the left panel and click the “Manage Cookies” button.
2. In Opera, in the cookie management window, you can find what you need, select it, and click the “Edit” button to see the contents of the entry. If you wish, you can edit the cookie.
3. In Mozilla FireFox, in order to get to cookies, you need to select the “Tools” section in the menu, and click “Settings” in it. In the settings window, go to the “Privacy” tab and click the button that says “Show Cookies...”. As a result, a window will open with a list of saved cookies, in which you can search and view their contents.
4. In Internet Explorer, the path to the cookie storage is through the menu section called “Tools” and the “Internet Options” item in it. Clicking on this item opens a window in which you need to, on the “General” tab, click on one of the “Options” buttons located in the “Browsing history” section. After this, the following window will open with the heading “Temporary File Options” where you need to click the button labeled “Show Files”.
5. Using this method in Internet Explorer, you will be taken to the folder where all temporary files are stored. If you click the “Name” column header, the files will be sorted by name and all cookies will be grouped into one block. You can find the one you need and open it for viewing and editing in a regular text editor.
6. The Google Chrome browser has the longest sequence of actions for acquiring access to cookies. First, you should click the wrench icon in the upper right corner of the window and select the “Options” option in the menu. This will open the Settings page, in the left pane of which you need to click on the Advanced link. On the advanced settings page, click the “Table of Contents Settings” button to open a new window.
7. In the new window, you need to click on the “All cookies and site data” button. This will be the final destination in the transition to cookies stored by the browser.
8. In Google Chrome you can view and delete cookies.
9. In the Safari browser, to access cookies, you also need to click the icon in the upper right corner - the one with a gear. In the menu, select “Settings...”, which will open a new window. In it you need to go to the “Security” tab and click the “Show Cookies” button. In Safari, you only have the option to search for and delete cookies.
Video on the topic
Modern browser programs remember everything for us: our favorite pages, everything that we have visited for a long time, passwords to all kinds of sites - mail, games, public networks. How comfortable it is to go to the site and no longer think about entering your login and password! But occasionally you have to reinstall the system and return all passwords from program memory to your own.
You will need
- – computer with Internet access
- – browser
1. Launch the Mozilla Firefox program, and in order to recover the password saved in this browser, execute the “Tools” command. Select the “Settings” menu item, go to the “Security” tab, click the “Saved Passwords” button. In this window, view all passwords saved in the browser, select the one you need and click “show”.
2. Download a program that will allow you to show saved passwords in the Opera program - UnWand - A program for viewing passwords (Wand - Wand) in Opera, as well as Opera password recovery 3.5.1.225 It will not be difficult to detect it. Install the program on your computer, run the program. Select the required password correction option: mechanically from a wand, mechanically from mail, manually from a wand, manually from mail, mixed option. Click the "Next" button. A scanning window will appear, in the next window you need to specify the location of the Opera program and click next. The program will scan this folder and display the saved passwords.
3. Download a program that can show passwords in the browser, not only in Opera or Mozilla, but also in many other browsers - Multi Password Recovery. To download, go to the formal website of the program - http://passrecovery.com/ru/index.php. Download and install this program on your computer. During installation, the program will ask you to check the update, click “OK”. Launch the program from the main menu. A menu will be displayed on the left in which you need to select the required program in order to recover your password. For example, the Internet Explorer browser, select it from the list, and the passwords saved in this browser will be shown on the right side of the program window.
4. To recover your password from a browser using another program, go to the website http://www.nirsoft.net/, select and download any program from there. Their functions are similar to the previous programs described.
Almost invariably, to maintain privacy when entering passwords, the corresponding programs display unreadable characters - “asterisks” instead of the entered characters. However, if you see these same asterisks in the password entry field, this does not mean that the password is truly placed in this field. Often, such asterisks do not hide anything, but have a purely informational function - to make you realize that when you enter the password, it will be hidden from prying eyes.
1. Give up the intention of deciphering asterisks in web pages received from the server. In the absolute majority of cases, passwords are not transmitted by the server to the user's browser. You can verify this by opening the initial page code received by your web browser - it will not contain the password, either in clear or encrypted form. Passwords are transmitted over the Internet in only one direction – from the browser to the server.
2. Use some specialized application program that can read passwords in open windows of other programs. There are no such tools as part of the service components of the operating system. It would be unusual for a decryption program to be bundled with password security programs. The required program is easy to find on the Internet - for example, it could be Pass Checker. The program consists of six files (including a help file) with a total weight of 296 kilobytes and does not require installation. Immediately after saving the files to a hard drive or removable media, you can launch it by double-clicking on the Password.exe file.
3. Open the program whose stars you care about. After that, place the Pass Checker window above the open program and with the left mouse button drag the image of the skull onto the field with the password hidden with asterisks. This field will be highlighted with a blinking frame, and in the Pass Checker window, opposite the window text, the decoder will place the password in its unencrypted form. This password can be copied and used in any way you wish.
4. Click the Help button in the bottom row of buttons if you want to use more difficult password decryption methods. In addition to the particularly simple one described in the previous step, the program provides two more options. Despite the English-language interface, the Pass Checker help is written in Russian, so there will be no problems with translation.
Video on the topic
The procedure for extracting accidentally moved files from the quarantine of the vast majority of antivirus programs is, more or less, standardized and differs only in details. In this case, we consider the operation of repairing quarantined files of Microsoft Security Essentials, Norton and Avast Antivirus applications.
You will need
- – Microsoft Security Essentials;
- – avast! Free Antivirus 5.0;
- – Norton Internet Security
1. Launch the Microsoft Security Essentials application and go to the “Log” tab in the main program window to perform the operation of extracting files from quarantine.
2. Select the item “Quarantined items” and click the “View data” button in the dialog box that opens.
3. Enter the password of the computer manager in the request window that appears and indicate the file to be repaired from quarantine in the list.
4. Click the “Restore” button to complete the file extraction procedure, or use the “Delete All” button to completely clear the quarantine of the Microsoft Security Essentials antivirus application.
5. Select the “Maintenance” menu item in the main window of the avast! antivirus program. Free Antivirus 5.0 and go to the “Quarantine” tab of the dialog box that opens.
6. Call the context menu of the file to be repaired in the list on the right side of the application window and specify the “Recover” command to extract the selected file to the original storage location specified in the “Initial location” section.
7. Select the “Quarantine” item in the “Security Log” window of the Norton Internet Security antivirus program and click the Options button to perform the operation of correcting a file placed in quarantine.
8. Specify the required file and select the “Restore this file” command in the “Danger Found” window that opens.
9. Click the “Yes” button in the new “Repair from Quarantine” dialog box and complete the correction operation by clicking the “Close” button.
Note!
Removing files from quarantine is allowed only if you are absolutely sure that they are harmless!
Helpful advice
It should be remembered that “Quarantine” is a special folder created by an antivirus application. Quarantined files are completely isolated from the operating system and are inaccessible to external processes. They cannot be launched, which ensures the safety of their storage.
The Windows operating system has a standard mechanism for introducing arbitrary data into dynamic libraries and executable modules, as well as an API for working with them. Images, string tables, sample dialogs, toolbars, menus and other information are added to PE modules as sources. Occasionally, for various purposes, it is necessary to extract sources from a compiled module.
You will need
- is a free Resource Hacker program available for download at rpi.net.au/~ajohnson/resourcehacker.
1. Upload the PE module file to Resource Hacker. In the main application menu, step by step click on the File and Open items or press the Ctrl+O key combination on your keyboard. The file open dialog will be displayed. Navigate to the directory where the target file is located. Select the PE module in the catalog listing. Click the "Open" button.
2. Determine the list of sources that need to be pulled. After loading the PE file, a tree structure will be displayed on the left side of the main Resource Hacker window. It is a list of all module sources grouped by type. So, say, dialogue sources are placed in the Dialog section, cursor sources - in the Cursor and Cursor Group sections, icons - in the Icon and Icon Group sections. The nodes of the second tier of the hierarchy, contained in the entire section, are numeric or symbolic identifiers of sources. Expand them and highlight nested elements. In this case, the corresponding sources will be visualized. Icons, cursors, and rasters will be displayed as images in the right panel of the main application window. For string tables, accelerators, version information, sample dialogs, menus, toolbars, code will be built and displayed in a format suitable for use with the RCC compiler. In addition, sample dialogs are visualized in a separate floating window.
3. Start the process of saving the sources discovered in the previous step. Select the required element in the tree structure on the left. Open the Action section of the main application menu. Select the item corresponding to the save operation of a particularly suitable type. Select the item “Save resource as a binary file …” if you want to save the source in the form of a fragment of binary data identical to that contained in the PE module. Select “Save resource as a *. res file …” to purchase a file containing a compiled version of the highlighted source. A similar file is suitable for linking with an application or library. Click on the item with text like “Save [Section name: subsection name: resource name] ...” in order to extract the sources in their original form. This menu item should be used to extract files of icons, cursors and images.
4. Pull out the sources. In the dialog with the title “Save resource to...”, specify the name and directory of the file to be saved. Click the "Save" button.
Occasionally, in the Windows operating system, a strange thing happens to a window of some program: when minimized and expanded to each screen, its behavior is typical, but in a medium-sized window, the application disappears beyond the visible area of the screen. There are methods for retrieving a window that has rolled off your desktop, and they are not that difficult.
You will need
- Windows OS.
1. The first method of extracting an object from a noticeable area is to entrust all manual operations for its positioning to the operating system itself. To do this, open, in addition to the problem window, one more window that belongs to any application - say, launch Explorer. After that, right-click on the free space on the taskbar to bring up the context menu. Give the OS a command to organize open windows using one of the methods listed in the menu - “Windows in a cascade”, “Display windows in a stack” or “Display windows side by side”. After this, the behavior of the lost window will return to normal.
2. Another method is to use keyboard control for window positioning. After turning it on, there will be no need to reach the window title with the mouse pointer in order to be able to move it. To enable this mode, press the hot key combination Alt + Space + P. After that, using the arrow keys, move the hidden window to the visible area of the desktop. To disable keyboard positioning mode, left-click anywhere.
3. 3rd method - stretching the available desktop space. This can be done by increasing the screen resolution. If you are using the latest versions of Windows 7 or Vista, right-click the background image on your desktop and select the item called “Screen Resolution” from the pop-up context menu. The OS will launch one of the “Control Panel” applets, where you need to open the “Resolution” drop-down list and move the slider up, or better yet, to the very top mark. Later, click the “Apply” button. The applet will change the resolution and start a timer, after which this metamorphosis will be canceled. Within the allotted time, you need to press the button to confirm the operation. Having done this, locate the missing window, move it to the center of the desktop and return the screen resolution to its previous value.
Among the information in cookies, user identification data is often in demand. Find out the login and password on Internet sources that save confidential data about their visitors.
You will need
- – PC running Windows operating system;
- - Internet access;
- – web browsers: Mozilla Firefox, Opera, Internet Explorer, Google Chrome;
- – Opera Password Recovery program;
- – BehindTheAsterisks utility.
1. If you use the Mozilla Firefox browser to view web pages with the cookie recording function activated in the settings, find out your saved logins and passwords easily in the software. Launch your Internet browser, open “Tools” and go to system settings. In the window that appears, containing several tabs, activate the “Security” option.
2. Click on the “Saved Passwords” button in the section that appears and go to a new web browser page. It has identification characters that are stored in the computer's memory when you visit different Internet sources. Click on the line “Display passwords". You can protect your confidential information and set a password in the same browser menu.
3. Find out usernames if you visit global network sources using the famous Opera browser. Open the Tools menu at the top of your web browser, use the Password Manager, and view the list of user logins.
4. Install additional software to access saved passwords, preferring the Opera Password Recovery utility for this purpose. Please remember that a third-party program does not guarantee the complete safety of your personal data.
5. While viewing passwords in the Google Chrome browser, open the corresponding option in the browser toolbar. Go to advanced settings and activate the “Show cookies” option.
6. Use the multifunctional free utility with a subconsciously accessible interface, BehindTheAsterisks, and find passwords in the cookies of the standard Internet Explorer browser. Go to the program options to display code words as symbols instead of asterisks and gain access to passwords.
Cookies are files that are stored on the user’s PC and contain information about the sites he has ever visited. With the support of cookies, you can find out which pages the user has visited.
Cookies are files with information about sites ever visited that are stored on the user’s computer. That is, when a user visits any web source, information about him is recorded in cookies and, upon further visiting this site, is transferred to the web server.
Cookies contain a variety of information, for example, account passwords on websites, sample color, font size that the user created for the site, etc. The clearest example of how cookies can be used to save settings is provided by the Google search engine. This machine provides the opportunity to customize your search results, we are talking about the number of results on the page, the format of the pages returned, the interface language and other settings. As for passwords for accounts on websites, every user has noticed more than once that having once specified his login and password on some web source, he did not do this again when re-authorizing, since this information about the site was mechanically recorded in cookies. When the source is visited again, the data is sent to the web server, which mechanically recognizes the user, freeing him from having to fill out the fields again. Cookies can also be useful for maintaining statistics. Cookies cannot pose any danger to your computer. This is just text data for everyone, unable to cause damage to him. With the support of cookies, it is impossible to delete, transfer or read information from the user’s PC, however, it is possible to find out which pages he visited. Modern browsers more readily provide the user with the choice of whether to save cookies or not, but if he chooses to disable the saving of cookies, he should be prepared for hiccups in working with some sites.
Disadvantages of cookiesFirst, cookies are not always likely to correctly identify a user. Secondly, they can be stolen by a criminal. As for incorrect recognition, the reason for this may be the use of several browsers by the user. Each browser has its own storage, therefore cookies do not identify the user, but his browser and PC, and if he has several browsers, then there will be several sets of cookies. Attackers may be attracted by the continuous exchange of cookies between the user’s browser and the web server; if the network traffic is not encrypted, it is possible to read the user’s cookies with the help of special sniffer programs. This problem can be solved by encrypting traffic and using different protocols.
Video on the topic
Cookies are a technology that allows a website to “remember” a user,
save his settings and not ask him for his login and password every time. Can
think that if you delete cookies in your browser, the site will not recognize you. But this one
Confidence is deceptive.
You can worry about your anonymity as much as you like, use a proxy
and VPN, forge HTTP request headers that reveal the system being used,
browser version, time zone and a lot of other information, but the website doesn’t care
There will still be ways to recognize the fact that you have already been there. In many
in cases this is not particularly critical, but not in a situation where at some
service you need to introduce yourself as another user or simply save
anonymity. It’s easy to imagine how the anti-fraud system of some kind of conventional
financial organization, if it determines that transactions were carried out from one computer
authorization under the accounts of completely different people. And isn't it nice?
realize that someone on the Internet can track your movements? Hardly. But
first things first.
Cookies have been used for centuries to identify users.
Cookies (from English "cookies") are a small piece of text information,
which the server sends to the browser. When a user accesses the server
(types its address in the browser line), the server can read the information,
contained in cookies, and based on its analysis, perform any actions.
For example, in the case of authorized access to something via the web in cookies
login and password are saved during the session, which allows the user not to
enter them again when prompted for each password-protected document. So
This way the website can "remember" the user. Technically it looks like
in the following way. When requesting a page, the browser sends a short
HTTP request text.
For example, to access the page www.example.org/index.html the browser
sends the following request to the www.example.org server:
GET /index.html HTTP/1.1
Host: www.example.org
The server responds by sending the requested page along with the text,
containing the HTTP response. This may instruct the browser to save cookies:
HTTP/1.1 200 OK
Content-type: text/html
Set-Cookie: name=value
If there is a Set-cookie line, the browser remembers the line name=value (name =
value) and sends it back to the server with each subsequent request:
GET /spec.html HTTP/1.1
Host: www.example.org
Cookie: name=value
Accept: */*
Everything is very simple. If the server received cookies from the client and it has them in
database, he can definitely process them. So, if it were cookies with
the user will not have some information about authorization at the time of visiting
you will be asked for login and password. According to the standard, cookies have a certain lifespan
(even though it can be very large), after which they die. And any
the user can easily delete saved cookies by using
the corresponding option, which is available in any browser. This fact is very
upsets the owners of many resources who do not want to lose touch with
visitor. It is important for them to track him, to understand that “this person was with us
yesterday, and the day before yesterday, etc." This is especially true for various analyzers
traffic, systems for maintaining statistics, banner networks, etc. This is where
the fun begins, because developers use all sorts of
tricks that many users are not even aware of. They're on the move
various tricks.
The thing is that in addition to the usual HTTP “goodies”, which everyone has long been interested in
got used to it, now alternative storages are actively used, where the browser
can write data on the client side. The first thing to mention is
storage of what you love and hate at the same time Flash (for those users who
which it is installed). Data is stored in so-called LSO (Local Shared
Objects) - files similar in format to cookies that are saved locally on
user's computer. The approach is in many ways similar to conventional "goodies" (in this
case, a small amount is also stored on the user’s computer.
text data), but has some advantages:
- Flash cookies are common to all browsers on a computer (unlike
from the classic cookie, which is tied to the browser). Settings, information
about the session, like, say, some identifier for tracking the user,
are not tied to any specific browser, but become common for
everyone. - Flash cookies allow you to store much more data (as
usually 100 KB), which increases the number of user settings,
available for saving.
In practice, LSO becomes a very simple and affordable tracking technology
user. Think about it: if I suggested you remove all the “goodies” in
system, would you remember about Flash cookies? Probably not. Now try to take
any viewer, for example, free
FlashCookiesView and see how many interesting things are recorded in
Flash repositories. A list of sites that really don’t want to
lose your trace, even if you clear your browser cache (along with the goodies).
But if advanced users and even more or less good users have heard about LSO
developers, then the existence of other data storage techniques, sometimes very
sophisticated (but effective), many do not even suspect. At least take new ones
repositories that appeared in
(Session Storage,
Local Storage, Global Storage, Database Storage via SQLite), about which you can
read in the article "". A Polish specialist was seriously confused by this problem
on safety Samy Kamkar. As a result, a special
Evercookie JavaScript library, which is specifically designed to
create the most durable cookies in the browser. Someone may ask: "Why
is this necessary?" Very simple: in order to uniquely identify
page visitor if he comes again. Such difficult-to-kill cookies are often
are called Tracking cookies and are even detected by some antiviruses as
threat to privacy. Evercookie can reduce all attempts to remain anonymous to
zero.
The secret is that evercookie uses everything available to the browser at once
storage: regular HTTP cookies, LSO, HTML5 containers. In addition, it comes into play
several cunning tricks that, with no less success, allow you to leave
computer the desired mark. Among them: generation of special PNG images,
using history browser, storing data using ETag tag, container
userData in Internet Explorer - it turns out that there are a lot of options.
You can see how effectively this works on the website.
developer -
http://samy.pl/evercookie. If you click on the "Click to create an
evercookie", cookies with a random number will be created in the browser. Try it
remove cookies wherever possible. I bet now you
I thought: “Where else can I delete cookies, except in the browser settings?”
Are you sure you deleted everything? Reload the page to be sure, you can even do it again
open browser. Now feel free to click on the “Click to rediscover cookies” button.
WTF? This did not prevent the site from taking data from somewhere - in the page fields
the number that was saved in cookies was displayed. But did we rub them? How
did it work? Let's try to understand some techniques.
An extremely interesting technique used in Evercookie is the approach
storing data in cached PNG images. When evercookie sets
cookies, it accesses the evercookie_png.php script with a special HTTP “bun”,
different from that used to store standard information about
sessions. These special cookies are read by a PHP script that creates
A PNG image in which all RGB (color) values are set according to
with information about the session. Ultimately the PNG file is sent to the client's browser
with the note: “the file must be cached for 20 years.”
Having received this data, evercookie deletes the previously created special
HTTP cookies, then makes the same request to the same PHP script, but not
providing information about the user. He sees that the data he is interested in
no, and it cannot generate a PNG. Instead, the browser returns
fake HTTP response "304 Not Modified" which causes it to pull the file from
local cache. The image from the cache is inserted into the page using the tag
HTML5 Canvas. Once this happens, evercookie reads every pixel
Canvas content, extracting the RGB values and thus restoring
the original cookie data that was stored in the image. Voila, that's it
works.
Another technique uses browser history directly. Once the browser
installs the bun, evercookie encodes the data using the Base64 algorithm,
which need to be preserved. Let's assume that this data is a string,
the resulting "bcde" after conversion to Base64. Library sequentially
accesses the following URLs in the background:
google.com/evercookie/cache/b
google.com/evercookie/cache/bc
google.com/evercookie/cache/bcd
google.com/evercookie/cache/bcde
google.com/evercookie/cache/bcde-
So these URLs are saved in history. Next comes a special
technique - CSS History Knocker, which, using a JS script and CSS, allows
check whether the user visited the specified resource or not (more details here -
samy.pl/csshack). For
evercookie bun checks run through all possible Base64 characters on
google.com/evercookie/cache, starting with the character "a" and moving on, but only
for one character. Once the script sees the URL that was accessed, it
starts searching for the next character. It turns out to be a kind of brute force. In practice
this selection is carried out extremely quickly, because there are no requests to
server are not executed. Search in history is carried out locally as much as possible
short term. The library knows it has reached the end of the line when the URL is
end with the symbol "-". We decode Base64 and get our data. How
name browser developers who allow this?
What happens if the user rubs his cookies? An important feature of the library itself
evercookie is that the user will have to try hard to
delete cookies left in different places - now there are 10 of them. If in at least one
If the cookie data remains in place, it will automatically be restored in all other
places. For example, if the user not only deletes his standard cookies, but
and clear LSO data, clean up HTML5 storages, which is already unlikely, anyway
The cookies created using the cached PNG and web history will remain. At
the next time you visit a site with evercookie, the library will not only be able to find
hidden bun, but will also restore them in all other places that
supports client browser. An interesting point is related to the transfer
"goodies" between browsers. If the user receives cookies in one browser,
that is, there is a high probability that they will be reproduced in others. The only thing
a necessary condition for this is saving the data in a Local Shared Object cookie.
The Evercookie library is completely open, so you can freely
use it and customize it to suit your needs. The server is not presented with any
serious requirements. All you need is access to a JS script in which
contains the evercookie code. To use Flash cookies (Local Shared Object),
there must be a file evercookie.swf in the folder with the script, and for the technician to work,
based on PNG caching and the use of ETag storage, access to
PHP scripts evercookie_png.php and evercookie_etag.php. Use evercookie
You can do this on any page of the site by connecting the following script:
var ec = new evercookie();
// set cookie "id" with value "12345"
// syntax: ec.set(key, value)
ec.set("id", "12345");
// restore the cookie with the name "id"
ec.get("id", function(value)
{
alert("Cookie value is " + value)
});
There is also another way to obtain cookies, based on using more
advanced callback function. This allows you to extract cookie values from
various storages used and compare them with each other:
function getCookie(best_candidate, all_candidates)
{
alert("The retrieved cookie is: " + best_candidate + "\n" + "You
can see what each storage mechanism returned " + "by looping through the all
candidates object.");
For (var item in all_candidates) document.write("Storage
mechanism " + item + " returned: " + all_candidates + "
");
}
ec.get("id", getCookie);
The evercookie library is available to everyone. It's a little scary, especially if
You have absolutely no idea what you can do against her.
There are no problems with clearing cookies in the browser and Flash. But try
delete the data wherever evercookie has been left behind! After all, if you leave the cookies in one
place - the script will automatically restore the value in all others
storages. Essentially this library is a good mode checker
privacy, which almost all browsers now have. And that's what I tell you
I’ll say: from Google Chrome, Opera, Internet Explorer and Safari, only the last one
"Private Browsing" mode completely blocked all methods used
evercookie. That is, after closing and opening the browser, the script could not
restore the value it left. There is reason to think. Moreover, in
in the near future, the developer evercookie promised to add more to the library
several data storage techniques, including using Isolated technology
Storage in Silverlight, as well as a Java applet.
It's probably worth starting with what cookies are and what they are needed for. A cookie is a piece of data that can be stored on the user’s side and used later to implement their ideas.
Let's imagine that on your website you have the opportunity to choose the color scheme of the site. It is very convenient to implement this on cookies, since the theme he selects will be visible only to him.
Cookies exist in both PHP and jQuery. Therefore, we will consider each case in more detail.
Detailed instructions for working with Cookies in jQuery1. Setting Cookies
Now we can try to create our first cookie:
$.cookie("cookie_name", "cookie_value", ( expires: 3, path: "/", domain: "your_site.ru", secure: true ));
What's what here?
“cookie_name” – cookie name;
“cookie_value” – cookie value;
“expires” – the number of days the cookies will be stored (in our case – 3 days). After this time, cookies will be automatically deleted;
“path” – availability of cookies on the site (in our case “/” - available on the entire site). If you wish, you can specify only a specific page or section where cookies will be available, for example, “/audio/rock”;
“domain” – the domain on which the cookie is valid. If you have a subdomain, you can specify it in this parameter, for example, “domain: “subdomain.your_site.ru””, and in this case the cookie will only be available on the domain “subdomain.your_site.ru”;
“ secure" – a parameter indicating that the cookie should be transmitted over the secure https protocol.
Here, not all parameters are required, and in order to set cookies, this construction will be sufficient:
$.cookie("cookie_name", "cookie_value", ( expires: 3, path: "/" ));
2. Receiving a Cookie
Getting cookies is quite simple; you can do this using the code:
$.cookie("cookie_name");
This code can be assigned to a variable and used for your needs:
var content = $.cookie("cookie_name"); if(content != null) ( alert("Cookie exists!"); ) else ( alert("Cookie does not exist!"); )
Agree, this is very convenient.
3. Removing Cookies
To remove a cookie value, set it to "null":
$.cookie("cookie_name", null);
This, I think, is the end of the introduction to working with Cookies in jQuery. This knowledge is quite enough to implement your ideas.
Detailed instructions for working with Cookies in PHPUnlike the previous option for working with cookies, you don’t need to connect anything here.
1. Setting Cookies
In order to set cookies in PHP, we will use the built-in “setcookie” function:
What's what here?
“cookie_name” – cookie name;
“cookie_value” – cookie value;
“time()+3600” – cookie lifetime in seconds (in our case – 1 hour). If you set the lifetime to “0”, the cookie will be deleted as soon as the browser is closed;
“/” – the section in which cookies are available (in our case, available throughout the site). If you want to limit the section in which cookies will be available, then replace “/” with, for example, “/audio/rock”;
“your_site.ru” – the domain on which the cookie will be available;
“true” – a parameter indicating that the cookie is only available via the secure https protocol. Otherwise the value is false ;
“false” – a parameter indicating that the cookie is available to scripting languages. Otherwise – true (available only via http).
Here, too, not all parameters are required, and to create cookies you will only need the following construction:
For convenience, the cookie value can be set via a variable:
2. Receiving a Cookie
In order to receive cookies, you need to use:
$_COOKIE["cookie_name"];
To eliminate errors due to possible missing cookies, use:
As in the previous example of working with Cookies in jQuery, cookies can be assigned to a variable:
3. Removing Cookies
Removing cookies in PHP is just as easy as in jQuery. All you have to do is set the cookie to an empty value and a negative time (time that has already passed):
Setcookie("cookie_name", "", time() - 3600);
The time in this example is an hour ago, which is quite enough to delete the cookies.
I would like to note that in some cases, using cookies is much more rational than using a database to implement the necessary functionality.
Cookies- information in the form of a text file saved on the user’s computer by the website. Contains authentication data (login/password, ID, phone number, mailbox address), user settings, access status. Stored in the browser profile.
Cookie hacking is the theft (or “hijacking”) of a web resource visitor’s session. Private information becomes available not only to the sender and recipient, but also to a third party - the person who carried out the interception.
Cookie Hacking Tools and TechniquesComputer thieves, like their colleagues in real life, in addition to skills, dexterity and knowledge, of course, also have their own tools - a kind of arsenal of master keys and probes. Let's take a look at the most popular tricks hackers use to extract cookies from Internet users.
SniffersSpecial programs for monitoring and analyzing network traffic. Their name comes from the English verb “sniff” (sniff), because. literally “sniff out” transmitted packets between nodes.
But attackers use a sniffer to intercept session data, messages and other confidential information. The targets of their attacks are mainly unprotected networks, where cookies are sent in an open HTTP session, that is, they are practically not encrypted. (Public Wi-Fi is the most vulnerable in this regard.)
To embed a sniffer into the Internet channel between the user node and the web server, the following methods are used:
- “listening” to network interfaces (hubs, switches);
- branching and copying traffic;
- connecting to a network channel gap;
- analysis through special attacks that redirect the victim’s traffic to the sniffer (MAC-spoofing, IP-spoofing).
The abbreviation XSS stands for Cross Site Scripting. Used to attack websites in order to steal user data.
The principle of XSS is as follows:
- an attacker inserts malicious code (a special disguised script) into a web page of a website, forum, or into a message (for example, when corresponding on a social network);
- the victim goes to the infected page and activates the installed code on his PC (clicks, follows a link, etc.);
- in turn, the executed malicious code “extracts” the user’s confidential data from the browser (in particular, cookies) and sends it to the attacker’s web server.
In order to “implant” a software XSS mechanism, hackers use all sorts of vulnerabilities in web servers, online services and browsers.
All XSS vulnerabilities are divided into two types:
- Passive. The attack is obtained by requesting a specific script on a web page. Malicious code can be injected into various forms on a web page (for example, into a site's search bar). The most susceptible to passive XSS are resources that do not filter HTML tags when data arrives;
- Active. Located directly on the server. And they are activated in the victim’s browser. They are actively used by scammers in all kinds of blogs, chats and news feeds.
Hackers carefully “camouflage” their XSS scripts so that the victim does not suspect anything. They change the file extension, pass off the code as an image, motivate them to follow the link, and attract them with interesting content. As a result: a PC user, unable to control his own curiosity, with his own hand (with a mouse click) sends session cookies (with login and password!) to the author of the XSS script - the computer villain.
Cookie substitutionAll cookies are saved and sent to the web server (from which they “came”) without any changes - in their original form - with the same values, strings and other data. Deliberate modification of their parameters is called cookie substitution. In other words, when replacing cookies, the attacker pretends to be wishful thinking. For example, when making a payment in an online store, the cookie changes the payment amount downwards - thus, “saving” on purchases occurs.
Stolen session cookies on a social network from someone else’s account are “inserted” into another session and on another PC. The owner of the stolen cookies gets full access to the victim's account (correspondence, content, page settings) as long as she is on her page.
“Editing” cookies is carried out using:
- “Manage cookies...” functions in the Opera browser;
- Cookies Manager and Advanced Cookie Manager addons for FireFox;
- IECookiesView utilities (Internet Explorer only);
- a text editor such as AkelPad, NotePad or Windows Notepad.
A very simple implementation scheme, consisting of several steps. But it is effective only if the victim’s computer with an open session, for example VKontakte, is left unattended (and for a long time!):
As a rule, hackers use the above tools (+ others) both in combination (since the level of protection on many web resources is quite high) and separately (when users are excessively naive).
XSS + snifferAnd most importantly, do not lose vigilance and attention while relaxing or working on the Internet!
