Web Server Penetration Testing Checklist: Enhancing Security and Mitigating Risks

Introduction

Web server penetration testing is a crucial aspect of ensuring the security and integrity of web applications and servers. By systematically assessing vulnerabilities and weaknesses, organizations can proactively identify and address potential security risks. In this blog post, we will explore the key categories and techniques involved in web server penetration testing. Additionally, we will discuss Microsoft’s essential checklist for securing web servers. Let’s dive in!

Categories of Web Server Penetration Testing:

Identity:

Web server penetration testing begins with establishing the identity of the target system and gathering pertinent information. This phase involves the following steps:

• Serial and Repeatable Tests: Conducting a series of methodical and repeatable tests allows testers to comprehensively assess different application vulnerabilities, including authentication weaknesses, configuration errors, and protocol-related vulnerabilities.
• Information Gathering: Collecting a wealth of information about the organization’s operating environment is critical during the initial stage of web server penetration testing. This includes focusing on areas such as network architecture, system configurations, and relevant personnel.
• Social Engineering Techniques: Utilizing social engineering techniques enables testers to gather valuable information about human resources, contact details, and other socially related data. This information can be leveraged to exploit potential security vulnerabilities.

Analysis:

Once the identity and initial information gathering are complete, the next step involves analyzing the target system to identify potential vulnerabilities. This phase includes the following steps:

• Web Server Fingerprinting: By fingerprinting the web server, testers can gather vital details such as the server name, server type, operating system, and the applications running on the server. Tools like Netcraft, HTTPrecon, and ID Serve assist in this process.
• Website Crawling: Systematic website crawling allows testers to extract specific information from web pages, including email addresses and other relevant data.
• Directory Enumeration: Enumerating web server directories helps extract important information about web functionalities, login forms, and other critical components.

Report Vulnerabilities:

The final phase of web server penetration testing involves reporting identified vulnerabilities to facilitate remediation. Here are some essential steps:

• Vulnerability Scanning: Performing vulnerability scanning using tools like HPwebinspect and Nessus aids in identifying weaknesses in the network infrastructure. These tools analyze potential vulnerabilities and determine if the system can be exploited.
• Exploitation Techniques: Exploiting vulnerabilities discovered during the testing process helps verify their impact and potential risks. This step provides crucial evidence to support the remediation process.
• MitM Attacks and Session Hijacking: Conducting man-in-the-middle (MitM) attacks allows testers to intercept communications between end-users and web servers, potentially accessing sensitive information. Session hijacking techniques, with tools like Burp Suite and Firesheep, automate the process of capturing valid session cookies and IDs.

Microsoft’s Essential Checklist for Web Server Security:

Services:

• Disable unnecessary Windows services.
• Run services with the least privileged accounts.
• Disable FTP, SMTP, and NNTP services if not required.
• Disable the Telnet service.

Protocols:

• Disable WebDAV if not used, or secure it if necessary.
• Harden the TCP/IP stack.
• Disable NetBIOS and SMB to close ports 137, 138, 139, and 445.

Accounts:

• Remove unused accounts from the server.
• Disable the guest account.
• Disable the IUSR_MACHINE account if not used by the application.
• Create a custom least-privileged anonymous account for applications requiring anonymous access.
• Enforce strong account and password policies.
• Restrict remote logins by removing the “Access this computer from the network” user right from the Everyone group.
• Avoid sharing accounts among administrators.
• Disable null sessions (anonymous logins).
• Require approval for account delegation.
• Prohibit users and administrators from sharing accounts.
• Limit the number of accounts in the Administrators group.

Files and Directories:

• Store files and directories on NTFS volumes.
• Place web content on a non-system NTFS volume.
• Store log files on a separate non-system NTFS volume.
• Restrict the Everyone group’s access to \WINNT\system32 or web directories.
• Deny write access to the web server root directory for anonymous Internet accounts.
• Deny write access to content directories for anonymous Internet accounts.
• Remove the remote administration application.
• Remove resource kit tools, utilities, and SDKs.
• Delete sample applications.

Shares:

• Remove unnecessary shares, including default administration shares.
• Restrict access to required shares, ensuring the Everyone group has no access.
• Remove administrative shares (C$ and Admin$) if not required (except for specific management tools).

Ports:

• Restrict internet-facing interfaces to ports 80 (and 443 if SSL is used).
• Encrypt intranet traffic or restrict it in the absence of a secure data center infrastructure.

Registry:

• Restrict remote registry access.
• Secure the SAM (HKLM\System\CurrentControlSet\Control\LSA\NoLMHash).

Auditing and Logging:

• Audit failed login attempts.
• Relocate and secure IIS log files.
• Configure log files with appropriate sizes based on security requirements.
• Regularly archive and analyze log files.
• Audit access to the Metabase.bin file.
• Configure IIS for W3C Extended log file format auditing.

Server Certificates:

• Ensure certificate date ranges are valid.
• Use certificates only for their intended purpose.
• Verify the certificate’s public key validity up to a trusted root authority.
• Confirm that the certificate has not been revoked.

Conclusion

Web server penetration testing is an essential process for identifying and addressing vulnerabilities in web applications and servers. By following a systematic approach that includes identity establishment, analysis, and vulnerability reporting, organizations can enhance the security of their web servers. Furthermore, implementing Microsoft’s essential checklist provides additional measures to secure web servers effectively. Remember, staying proactive in the face of evolving threats is crucial to maintaining a robust web server environment.