**Web server hacking** - this is the exploitation of vulnerabilities that exist in a web server. Web servers are computer systems responsible for serving web pages and accepting requests from various users. The attackers target these web servers to gain unauthorized access to certain information, disrupt the services of the websites or compromise their integrity. End
Most typical techniques that hackers use when compromising web servers include: ***//***
1. **Utilization of Vulnerabilities within Web Servers Operating Systems**
Web Servers such as: **Apache, Nginx, Internet Information Services IIS (Internet Information Services)** plus so many others contain vulnerabilities due to:
Outdated applications. Old unpatched, with known exploits open to utilization, web server application versions.
- **Misconfigured Settings**: Malicious details or access might be provided due to incorrect configuration of servers.
For example, the **Apache Struts** vulnerabilities, namely **CVE-2017-5638**, were extremely exploited during the Equifax breach, because their security vulnerability was left unpatched.
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### 2. SQL Injection (SQLi)
SQL injection is an attack vector where a malicious SQL is injected in the input field of a website or even in an URL which convinces a web server to execute its code. It can possibly allow hackers to:
- **Access the database**: obtain sensitive information such as username, password, and credit card data.
- **Modify or delete data**: modify or delete the content in the database.
- **Privilege escalation**: gain control over the web server.
Example: A weakly designed login form might accept `'admin' OR '1'='1` as a password and then authenticated the attacker to log in on the admin panel.
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### 3. **Cross-Site Scripting (XSS)**
**Cross-Site Scripting** (XSS) is a type of attack where an attacker injects malicious scripts into web pages that other users view. These scripts can steal cookies, session tokens, or other sensitive data. XSS can be used to:
- **Hijack user sessions**: By stealing session cookies, attackers can impersonate legitimate users.
- **Deface websites**: The attacker might inject scripts that alter the appearance of the website or spread malware.
Example: An attacker may inject a script into a comment section of a website. When other users view the comment, their session cookies are stolen and sent to the attacker.
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### 4. **Remote File Inclusion (RFI) / Local File Inclusion (LFI)**
These vulnerabilities occur when a web application allows users to include files in the server environment. The server may include malicious files or files from external sources, leading to:
- **Remote File Inclusion (RFI)**: The attacker can instruct the server to load malicious scripts from an external server, often used for deploying malware.
- **Local File Inclusion (LFI)**: The attacker can read sensitive files on the server, such as `/etc/passwd` on Linux, which may lead to credential theft or privilege escalation.
Example: An attacker might manipulate a URL to include a local file (e.g., `http://example.com/page.php?file=././././etc/passwd`) to gain access to sensitive files on the server.
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### 5. **Brute Force Attacks**
Brute force attacks involve systematically trying every possible combination of login credentials (such as usernames and passwords) until the correct one is found. Attackers use automated tools to guess:
- **Admin login credentials** to gain full control of the web server.
- **FTP, SSH, or cPanel login credentials** for accessing the server via the interfaces.
Illustration: With a dictionary attack, the attacker can attack weak passwords such as "123456" or "password" to breach the admin account.
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### 6. Denial of Service (DoS) / Distributed Denial of Service (DDoS) Attacks
These types of attacks try to prevent or impair the availability of a legitimate website or web server to other users by flooding it with an enormous amount of traffic or requests.
- **DoS Attack**: A single computer initiates a large number of requests, slowing down the server or causing it to crash.
- **DDoS Attack**: A distributed attack floods a server with traffic using multiple compromised computers usually belonging to a botnet.
Example: The attacker uses a botnet to create millions of HTTP requests that cause the server to crash or become unresponsive.
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### 7. **Privilege Escalation**
Privilege escalation occurs when an attacker exploits weaknesses in the server or web application to obtain higher levels of access than authorized. This can happen in a variety of ways:
- **Server configuration vulnerabilities** (such as using default credentials or weak permissions).
- **Exploiting web application flaws** to obtain admin privileges.
Example: An attacker can access the user account at first, but through an unpatched vulnerability, escalate to the admin account.
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### 8. **Session Fixation**
When a session fixation attack takes place, the attacker sets a valid session ID for a target user and gets the server to authenticate him using that session. Afterward, the attacker hijacks the session, hence achieving unauthorized access to the web application.
Example: The attacker can send a victim a link with a pre-set session ID, for example `http://victim.com?sessionid=attacker1234`, and when the victim logs in, the attacker can use that session to pretend to be the victim.
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### 9. Exploiting File Upload Vulnerabilities
Most websites provide for users to upload files such as profile pictures and documents. Attackers exploit such features of file uploads by uploading malware files such as:
- **Web shells**: Malicious scripts that allow the attacker to remotely control the server.
- **Malicious executables**: Files that execute malicious code when opened.
Example: A website that allows users to upload images may not filter the file types properly, allowing the attacker to upload a PHP script instead of an image.
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### 10. Weak Security Configurations
Poorly configured web servers might expose sensitive data, or have inadequate access control measurements. Some common misconfiguration issues include:
- Default server configurations: Servers usually possess default usernames, passwords and configurations that are easy for hackers to guess.
- Unwanted services running: Servers may harbor unnecessary services such as running FTP, Telnet, to mention a few, which exposes additional entry points for an attacker.
- **Exposure of files and directories**: Sensitive data - for example, database configuration details, log files - will be exposed through either wrongly set permissions or directory listing.
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### 11. **Social Engineering**
Social engineering entails manipulating people into divulging sensitive information or taking some action that compromises security. In the context of web server hacking:
- Attackers will try to manipulate administrators into revealing passwords or any other credentials.
- **Phishing emails** might be sent to staff, leading to credential theft or malware installation.
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### How to Defend Against Web Server Hacking
1. **Regular Software and Patch Updates**: Keep your web server software, CMS (Content Management System), and all related plugins or modules updated with the latest security patches.
2. **Web Application Firewall (WAF)**: Implement a WAF to filter and monitor HTTP traffic to the server, blocking malicious requests.
3. **Secure Coding Practices**: Build applications using secure coding practices, such as input validation, to avoid SQL injection, XSS, and other attacks.
4. **Strong Authentication Mechanisms**: Implement strong multi-factor authentication for your web server administration and key parts of your website.
5. **Encryption**: Employ SSL/TLS encryption for data transferred from the client to the server so that your login credentials, or similar sensitive information, aren't exposed over the wire.
6. **Limit Server Permissions**: Use the principle of least privilege (PoLP), so access to the sensitive parts of the server is restricted, and accounts have just enough privileges.
7. **Regular Backups**: Make regular backups of the server and databases in case an attack happens or data is lost.
8. **Penetration Testing**: Conduct regular penetration testing of your web server and application to check for vulnerabilities.
Such activities have severe repercussions such as data breaches, unauthorized access, and service disruption in hacking of web servers. Nonetheless, administrators can minimize the risk involved in hacking and ensure safe servers by knowing common attacks made by attackers and securing measures. For a long-term web server environment to remain safe, constant security audits, updates, and sound coding practices should be made in software.
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