Pentesting on web application cookies

 
We will first focus on what exactly cookies are and how they work.
It would be easy for you to understand the test cases for testing cookies when you have clear understanding of how cookies work?
How cookies stored on hard drive? 
And how can we edit cookie settings?
What is Cookie?
Cookie is small information stored in text file on user’s hard drive by web server. This information is later used by web browser to retrieve information from that machine. Generally cookie contains personalized user data or information that is used to communicate between different web pages.
Why Cookies are used?
Cookies are nothing but the user’s identity and used to track where the user navigated throughout the web site pages. The communication between web browser and web server is stateless.
For example if you are accessing domain http://www.example.com/1.html then web browser will simply query to example.com web server for the page 1.html. Next time if you type page as http://www.example.com/2.html then new request is send to example.com web server for sending 2.html page and web server don’t know anything about to whom the previous page 1.html served.
What if you want the previous history of this user communication with the web server? You need to maintain the user state and interaction between web browser and web server somewhere. This is where cookie comes into picture. Cookies serve the purpose of maintaining the user interactions with web server.
How cookies work?
The HTTP protocol used to exchange information files on the web is used to maintain the cookies. There are two types of HTTP protocol. Stateless HTTP and Stateful HTTP protocol. Stateless HTTP protocol does not keep any record of previously accessed web page history. While Stateful HTTP protocol do keep some history of previous web browser and web server interactions and this protocol is used by cookies to maintain the user interactions.
Whenever user visits the site or page that is using cookie, small code inside that HTML page (Generally a call to some language script to write the cookie like cookies in JAVAScript, PHP, Perl) writes a text file on users machine called cookie.
Here is one example of the code that is used to write cookie and can be placed inside any HTML page:
Set-Cookie: NAME=VALUE; expires=DATE; path=PATH; domain=DOMAIN_NAME;
When user visits the same page or domain later time this cookie is read from disk and used to identify the second visit of the same user on that domain. Expiration time is set while writing the cookie. This time is decided by the application that is going to use the cookie.
Generally two types of cookies are written on user machine.
1) Session cookies: This cookie is active till the browser that invoked the cookie is open. When we close the browser this session cookie gets deleted. Some time session of say 20 minutes can be set to expire the cookie. 2) Persistent cookies: The cookies that are written permanently on user machine and lasts for months or years.
Where cookies are stored?
When any web page application writes cookie it get saved in a text file on user hard disk drive. The path where the cookies get stored depends on the browser. Different browsers store cookie in different paths. E.g. Internet explorer store cookies on path “C:\Documents and Settings\Default User\Cookies”
Here the “Default User” can be replaced by the current user you logged in as. Like “Administrator”, or user name like “Vijay” etc.
The cookie path can be easily found by navigating through the browser options. In Mozilla Firefox browser you can even see the cookies in browser options itself. Open the Mozila browser, click on Tools->Options->Privacy and then “Show cookies” button.
How cookies are stored?
Lets take example of cookie written by rediff.com on Mozilla Firefox browser:
On Mozilla Firefox browser when you open the page rediff.com or login to your rediffmail account, a cookie will get written on your Hard disk. To view this cookie simply click on “Show cookies” button mentioned on above path. Click on Rediff.com site under this cookie list. You can see different cookies written by rediff domain with different names.
Site: Rediff.com Cookie name: RMID Name: RMID (Name of the cookie) Content: 1d11c8ec44bf49e0… (Encrypted content) Domain: .rediff.com Path: / (Any path after the domain name) Send For: Any type of connection Expires: Thursday, December 31, 2020 11:59:59 PM
Applications where cookies can be used:
1) To implement shopping cart:
Cookies are used for maintaining online ordering system. Cookies remember what user wants to buy. What if user adds some products in their shopping cart and if due to some reason user don’t want to buy those products this time and closes the browser window? When next time same user visits the purchase page he can see all the products he added in shopping cart in his last visit.
2) Personalized sites:
When user visits certain pages they are asked which pages they don’t want to visit or display. User options are get stored in cookie and till the user is online, those pages are not shown to him.
3) User tracking:
To track number of unique visitors online at particular time.
4) Marketing:
Some companies use cookies to display advertisements on user machines. Cookies control these advertisements. When and which advertisement should be shown? What is the interest of the user? Which keywords he searches on the site? All these things can be maintained using cookies.
5) User sessions:
Cookies can track user sessions to particular domain using user ID and password.
Drawbacks of cookies:
1) Even writing Cookie is a great way to maintain user interaction, if user has set browser options to warn before writing any cookie or disabled the cookies completely then site containing cookie will be completely disabled and can not perform any operation resulting in loss of site traffic.
2) Too many Cookies:
If you are writing too many cookies on every page navigation and if user has turned on option to warn before writing cookie, this could turn away user from your site.
3) Security issues:
Some times users personal information is stored in cookies and if someone hack the cookie then hacker can get access to your personal information. Even corrupted cookies can be read by different domains and lead to security issues.

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4) Sensitive information:
Some sites may write and store your sensitive information in cookies, which should not be allowed due to privacy concerns.
This should be enough to know what cookies are. 
Some Major Test cases for web application cookie testing:
The first obvious test case is to test if your application is writing cookies properly on disk. You can use the Cookie Tester application also if you don’t have any web application to test but you want to understand the cookie concept for testing.
Security Test cases: 
1) As a Cookie privacy policy make sure from your design documents that no personal or sensitive data is stored in the cookie.
2) If you have no option than saving sensitive data in cookie make sure data stored in cookie is stored in encrypted format.
3) Make sure that there is no overuse of cookies on your site under test. Overuse of cookies will annoy users if browser is prompting for cookies more often and this could result in loss of site traffic and eventually loss of business.
4) Disable the cookies from your browser settings: If you are using cookies on your site, your sites major functionality will not work by disabling the cookies. Then try to access the web site under test. Navigate through the site. See if appropriate messages are displayed to user like “For smooth functioning of this site make sure that cookies are enabled on your browser”. There should not be any page crash due to disabling the cookies. (Please make sure that you close all browsers, delete all previously written cookies before performing this test)
5) Accepts/Reject some cookies: The best way to check web site functionality is, not to accept all cookies. If you are writing 10 cookies in your web application then randomly accept some cookies say accept 5 and reject 5 cookies. For executing this test case you can set browser options to prompt whenever cookie is being written to disk. On this prompt window you can either accept or reject cookie. Try to access major functionality of web site. See if pages are getting crashed or data is getting corrupted.
6) Delete cookie: Allow site to write the cookies and then close all browsers and manually delete all cookies for web site under test. Access the web pages and check the behavior of the pages.
7) Corrupt the cookies: Corrupting cookie is easy. You know where cookies are stored. Manually edit the cookie in notepad and change the parameters to some vague values. Like alter the cookie content, Name of the cookie or expiry date of the cookie and see the site functionality. In some cases corrupted cookies allow to read the data inside it for any other domain. This should not happen in case of your web site cookies. Note that the cookies written by one domain say rediff.com can’t be accessed by other domain say yahoo.com unless and until the cookies are corrupted and someone trying to hack the cookie data.
8 ) Checking the deletion of cookies from your web application page: Some times cookie written by domain say rediff.com may be deleted by same domain but by different page under that domain. This is the general case if you are testing some ‘action tracking’ web portal. Action tracking or purchase tracking pixel is placed on the action web page and when any action or purchase occurs by user the cookie written on disk get deleted to avoid multiple action logging from same cookie. Check if reaching to your action or purchase page deletes the cookie properly and no more invalid actions or purchase get logged from same user.
9) Cookie Testing on Multiple browsers: This is the important case to check if your web application page is writing the cookies properly on different browsers as intended and site works properly using these cookies. You can test your web application on Major used browsers like Internet explorer (Various versions), Mozilla Firefox, Netscape, Opera etc.
10) If your web application is using cookies to maintain the logging state of any user then log in to your web application using some username and password. In many cases you can see the logged in user ID parameter directly in browser address bar. Change this parameter to different value say if previous user ID is 100 then make it 101 and press enter. The proper access message should be displayed to user and user should not be able to see other users account.
These are some Major test cases to be considered while testing website cookies. You can write multiple test cases from these test cases by performing various combinations. If you have some different application scenario, you can mention your test cases in comments below.

Session fixation Attack with example

Description:

Session Fixation is an attack that permits an attacker to hijack a valid user session. The attack explores a limitation in the way the web application manages the session ID, more specifically the vulnerable web application. When authenticating a user, it doesn’t assign a new session ID, making it possible to use an existent session ID. The attack consists of obtaining a valid session ID (e.g. by connecting to the application), inducing a user to authenticate himself with that session ID, and then hijacking the user-validated session by the knowledge of the used session ID. The attacker has to provide a legitimate Web application session ID and try to make the victim's browser use it.
The session fixation attack is a class of Session Hijacking, which steals the established session between the client and the Web Server after the user logs in. Instead, the Session Fixation attack fixes an established session on the victim's browser, so the attack starts before the user logs in.
There are several techniques to execute the attack; it depends on how the Web application deals with session tokens. Below are some of the most common techniques:
• Session token in the URL argument: The Session ID is sent to the victim in a hyperlink and the victim accesses the site through the malicious URL.
• Session token in a hidden form field: In this method, the victim must be tricked to authenticate in the target Web Server, using a login form developed for the attacker. The form could be hosted in the evil web server or directly in html formatted e-mail.
• Session ID in a cookie:
o Client-side script
Most browsers support the execution of client-side scripting. In this case, the aggressor could use attacks of code injection as the XSS (Cross-site scripting) attack to insert a malicious code in the hyperlink sent to the victim and fix a Session ID in its cookie. Using the function document.cookie, the browser which executes the command becomes capable of fixing values inside of the cookie that it will use to keep a session between the client and the Web Application.
o <META> tag
<META> tag also is considered a code injection attack, however, different from the XSS attack where undesirable scripts can be disabled, or the execution can be denied. The attack using this method becomes much more efficient because it's impossible to disable the processing of these tags in the browsers.
o HTTP header response
This method explores the server response to fix the Session ID in the victim's browser. Including the parameter Set-Cookie in the HTTP header response, the attacker is able to insert the value of Session ID in the cookie and sends it to the victim's browser. 

Example 1

The example below explains a simple form, the process of the attack, and the expected results.
(1)The attacker has to establish a legitimate connection with the web server which (2) issues a session ID or, the attacker can create a new session with the proposed session ID, then, (3) the attacker has to send a link with the established session ID to the victim, she has to click on the link sent from the attacker accessing the site, (4) the Web Server saw that session was already established and a new one need not to be created, (5) the victim provides his credentials to the Web Server, (6) knowing the session ID, the attacker can access the user's account.

Figure 1. Simple example of Session Fixation attack.

---------------------------------------Thanks to OWASP--------------------------------------

BankMirage - Banking Malware Pulled From Google Play

Mobile banking is very convenient, allowing users to access their bank account and manage their finances without actually visiting the bank. Unfortunately, mobile banking apps are a constant target for hackers. A recent blog post from Lookout reveals a cloned banking app that targets user logins was recently at large in the Google Play app store.
A Wolf in Sheep's Clothing
The malware is called BankMirage. It works by wrapping itself around a bank's original app, which in this case was the Israeli bank Mizrahi Bank. Attackers then successfully uploaded the app to the Google Play store. When customers opened the app, they would be instructed to enter their login information at which point the malware grabs the user's ID. After entering the correct information, the user then gets an error message saying their login was incorrect and to install the real app from Google Play.
The interesting part about BankMirage is that it only steals the user ID. Perhaps the hackers already have a huge cache of passwords and only need the user IDs or that BankMirage is the foundation for a round of very targeted phishing attacks in the future. Another plausible scenario is that the creators of BankMirage plan to sell their stack of IDs to other hackers for a price, further increasing the risk of a compromised bank account.
"At this point, it's still very curious even to us why the authors would only want to collect the usernames and not passwords," said Meghan Kelly, Security Communications Manager at Lookout. "However, it could be that they were testing the app's functionality before moving forward in development."
Fool Me Twice
The process of stealing login information is nothing new. The Zeus Trojan, which targets sensitive banking information and email accounts, returned last year. There are many variations of the program, which makes sense when considering that BankMirage's tactics are used by other malware programs.
Another banking Trojan called WroBa.D not only takes login information, but is also capable of intercepting SMS messages. This allows hackers to potentially get the authorization code before users have a chance to see it, giving hackers complete access to a bank account. The malware has seven variants and targets six banks in South Korea, and disguises itself on devices as a fake Google Play app.
South Korea is an appropriate target because its citizens have been using mobile banking applications since 2000. In 2008, 22.8 trillion won or the equivalent of $22.5 billion was exchanged through online banking. Mobile devices accounted for 151 billion won or $149 million of those transactions.
Prevention
The terrifying part about the malware is that it exists inside Google Play. We always recommend that our readers only download apps from Google Play, but as this malware and past experience shows, it's still possible for malicious software to make their way into the Google Play store.
Lookout advises concerned readers to use their best judgement when downloading apps. Check to see if the banking app has a duplicate app and determine which one is the real deal. Be on the lookout for spelling errors, which usually indicates that the app is up to no good. For example WroBa.D utilizes the Google Play icon, but name below the icon reads as "googl app stoy."

Apktool for Android security test in Windows

 
 


Use APKTool to Decompile, Edit, Translate and Recompile an APK

APKTool is an application  which decompiles and recompiles android APKs. If you know what you are doing, it also allows you to debug the smali code step by step. In our case it will enable us to build a language pack by translating the .xml strings inside APK files. 
This tutorial is for the Windows version of APKtool.
 The Google.Code page for APKTool is here, however, we have prepackaged everything you need and uploaded it here
The Video Tutorial is Below:
The Supplementary guide to common errors in APKTool is below:
You need to do the following preparations (the video outlines these steps anyway):

1. Download the prepackaged APKTool zip.
2. Extract them to a directory you will remember.
3. Extract framework-res.apk AND apk files you want to decompile from the MIUI_Au ROM and copy them to the root directory of APKTool.

This step must be completed every time you are dealing with APKTool:

1. Open a command window
2. Navigate to the root directory of APKtool and type the following command:
   apktool if framework-res.apk

The output should be:
I: Framework installed to: C:\Users\Josh\apktool\framework\1.apk
This step does the actual decompiling of the APK (I will assume that the chosen APK is Settings.apk):
apktool d Settings.apk
The output should be:
I: Loading resource table…
I: Decoding resources…
I: Copying assets and libs…
After doing that, a new directory with the name of the APK you decompiled should have been created. You need to:

1. Change into the newly created directory.
2. Change into the /res folder
3. Check to see if a values-xx folder exists, where xx is the two letter code of the target language to be translated into. For example, if you are aiming to translate into German, check for a values-de folder. If it does not exist (and chances are that if you are translating into a new language, that it will not exist), you need to create it. Then, copy the arrays.xml and strings.xml files from the /values folder into the folder you just created.
4. Open these two files (in Notepad ++) and alter the strings (the text in BLACK ONLY).  Look out for things that look like  %d and %s /’  -    Don’t edit these, as they are variables.  Also, if you see &amp;, it represents the ‘&’ sign, so feel free to change it. Finally, you MUST be sure to place a backslash ‘\’ before an apostrophe, for example Proxy\’s would be the equivalent of Proxy’s.
5. Once you have translated and edited your arrays.xml and strings.xml files, save them, and return to the root directory of APKTool.
6. Open a command prompt to that directory

Enter the following command to recompile your edited and translated APK (assuming that Settings.apk is the chosen APK):
apktool b Settings
The output should be:
I: Checking whether sources has changed…
I: Smaling…
I: Checking whether resources has changed…
I: Building resources…
I: Building apk file…
You may get a couple of these messages:
aapt: warning: string ‘app_killed_message’ has no default translation in C:\Users\Josh\Desktop\NF\framework-res\res; found: fr it ja
aapt: warning: string ‘global_action_reboot’ has no default translation in C:\Users\Josh\Desktop\NF\framework-res\res; found: fr it ja
aapt: warning: string ‘reboot_system’ has no default translation in C:\Users\Josh\Desktop\NF\framework-res\res; found: fr it ja
aapt: warning: string ‘toast_reboot_recommend’ has no default translation in C:\Users\Josh\Desktop\NF\framework-res
However,  it will build the apk anyway. These messages mean that some strings don’t have values. It is only an issues if the text im blue includes your translation language.
Once that is done, two directories will have been created within the decompilation directory. One will be called “dist”, and this is where it will place a built, but not signed, apk file. The other one is called “build”, and here it will place everything “loose” (the contents of the APK).
I have trouble using the APK files it spits out in the /dist folder ( they force closes if they are an application, or bootloop it a framework-res.apk; I think the reason is because Android will not accept APK files that are not signed).  Instead, copy the resources.arsc from the /build directory into the original framework-res from the rom (just overwrite the old resources.arsc one with the new one).
This tutorial is for the Windows version of APKtool.