Web server vulnerabilities
A web server is a program that stores files i.e. web pages and they are accessible via the network or internet. A web server requires both hardware and software. Attackers usually hack web server by exploiting the software to gain authorized access to the server. Let’s look at some of the common vulnerabilities that attackers take advantage of and hack web server.
Default settings– These settings such as default user id and passwords can be easily guessed by the attackers. Default settings might also allow performing certain tasks such as running commands on the server which can be exploited.
Misconfiguration of operating systems and networks – certain configurations such as allowing users to execute commands on the server can be dangerous if the user does not have a good password.
Bugs in the operating system and web servers– discovered bugs in the operating system or web server software can also be exploited to gain unauthorized access to the system.
In addition to the above-mentioned web server vulnerabilities, the following can also be led to unauthorized access
Lack of security policy and procedures– lack of a security policy and procedures such as updating antivirus software, patching the operating system, and web server software can create security loopholes for attackers.
Types of Web Servers
- Apache– This is the commonly used web server on the internet. It is cross-platform but is it’s usually installed on Linux. Most PHP websites are hosted on Apache servers.
Internet Information Services (IIS)– It is developed by Microsoft. It runs on windows and is the second most used web server on the internet. Most asp and aspx websites are hosted on IIS servers.
- Apache Tomcat – Most Java server pages (jsp) websites are hosted on this type of web server.
- Other web servers – These include Novell’s Web Server and IBM’s Lotus Domino servers.
Types of Attacks against Web Servers
- Directory traversal attacks– This type of attack exploits bugs in the web server to gain unauthorized access to files and folders that are not in the public domain. Once the attacker has gained access, they can download sensitive information, execute commands on the server, or install malicious software.
- Denial of Service Attacks– With this type of attack, the web server may crash or become unavailable to legitimate users.
- Domain Name System Hijacking – With this type of attacker, the DNS setting is changed to point to the attacker’s web server. All traffic that was supposed to be sent to the webserver is redirected to the wrong one.
- Sniffing– Unencrypted data sent over the network may be intercepted and used to gain unauthorized access to the web server.
- Phishing– With this type of attack, the attack impersonates the websites and directs traffic to the fake website. Unsuspecting users may be tricked into submitting sensitive data such as login details, credit card numbers, etc.
- Pharming– With this type of attack, the attacker compromises the Domain Name System (DNS) servers or on the user computer so that traffic is directed to a malicious site.
- Defacement– With this type of attack, the attacker replaces the organization’s website with a different page that contains the hacker’s name, images and may include background music and messages.
Effects of successful attacks
An organization’s reputation can be ruined the attacker edits the website content and includes malicious information or links to a porn website
The web server can be used to install malicious software on users who visit the compromised website. The malicious software downloaded onto the visitor’s computer can be a virus, Trojan or botnet software, etc.
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Compromised user data may be used for fraudulent activities which may lead to business loss or lawsuits from the users who entrusted their details with the organization.
Some Web server attack tools
- Metasploit– this is an open-source tool for developing, testing, and using exploit code. It can be used to discover vulnerabilities in web servers and write exploits that can be used to compromise the server.
- MPack– this is a web exploitation tool. It was written in PHP and is backed by MySQL as the database engine. Once a web server has been compromised using MPack, all traffic to it is redirected to malicious download websites.
- Zeus– this tool can be used to turn a compromised computer into a bot or zombie. A bot is a compromised computer that is used to perform internet-based attacks. A botnet is a collection of compromised computers. The botnet can then be used in a denial of service attack or sending spam emails.
- No split – this tool can be used to install programs, delete programs, replicating it, etc.
How to avoid attacks on the Web server
An organization can adopt the following policy to protect itself against web server attacks.
- Patch management– this involves installing patches to help secure the server. A patch is an update that fixes a bug in the software. The patches can be applied to the operating system and the web server system.
- Vulnerability scanning system– these include tools such as Snort, NMap, Scanner Access Now Easy (SANE)
Firewalls can be used to stop simple DoS attacks by blocking all traffic coming the identify source IP addresses of the attacker.
Antivirus software can be used to remove malicious software on the server
Disabling Remote Administration
Default accounts and unused accounts must be removed from the system
Default ports & settings (like FTP at port 21) should be changed to custom port & settings (FTP port at 5069)
Hacking Activity: Hack a WebServer
In this practical scenario, we are going to look at the anatomy of a web server attack. Let’s assume we are targeting www.techpanda.org. We are not going to hack into it as this is illegal. We will only use the domain for educational purposes.
How To Hack Web Server
What we will need
- A target www.techpanda.org
- Bing search engine
- SQL Injection tools
- PHP Shell, we will use dk shell http://sourceforge.net/projects/icfdkshell/
We will need to get the IP address of our target and find other websites that share the same IP address.
We will use an online tool to find the target’s IP address and other websites sharing the IP address
- Enter the URL http://www.yougetsignal.com/tools/web-sites-on-web-server/ in your web browser
- Enter www.techpanda.org as the target
- Click on Check button
- You will get the following results
Based on the above results, the IP address of the target is 188.8.131.52
We also found out that there are 403 domains on the same web server.
Our next step is to scan the other websites for SQL injection vulnerabilities. Note: if we can find a SQL vulnerable on the target, then we would directly exploit it without considering other websites.
Enter the URL www.bing.com into your web browser. This will only work with bing so don’t use other search engines such as Google or yahoo
Enter the following search query
- “IP:184.108.40.206” limits the search to all the websites hosted on the web server with IP address 220.127.116.11
- “.php?id=” search for URL GET variables used a parameters for SQL statements.
You will get the following results
As you can see from the above results, all the websites using GET variables as parameters for SQL injection have been listed.
The next logical step would be to scan the listed websites for SQL Injection vulnerabilities. You can do this using Manual SQL injection or using tools listed in this article on SQL Injection.
Uploading the PHP Shell
We will not scan any of the websites listed as this is illegal. Let’s assume that we have managed to log in to one of them. You will have to upload the PHP shell that you downloaded fromhttp://sourceforge.net/projects/icfdkshell/
- Open the URL where you uploaded the dk.php file.
- You will get the following window
- Clicking the Symlink URL will give you access to the files in the target domain.
Once you have access to the files, you can get login credentials to the database and do whatever you want such as defacement, downloading data such as emails, etc.
This Post is Strictly for EDUCATIONAL PURPOSES. Don’t use it in a bad manner. It can be a punishable offense.