Bypass the Blocked IP address while Pentesting.

IP blocking is a common method used by websites and firewalls to restrict access, either by banning known malicious IP addresses or by limiting access to certain geographic regions. However, IP blocking has limitations, and attackers (or ethical pentesters) may use various techniques to bypass these filters. Here are methods used in ethical testing to assess and strengthen IP-based controls.

Proxy Servers: Use of proxy servers is a basic method of changing IP addresses. In penetration testing, proxies help simulate how an attacker might use distributed networks to avoid detection.VPNs (Virtual Private Networks): VPNs can change the tester’s IP address and location, which is useful when testing geo-blocking. Ethical penetration testers often use VPNs to simulate access from different regions.TOR Network: The Tor network allows for anonymity and provides an exit node IP that changes frequently. Although slower, this can be an effective way to evaluate how well a site handles traffic from anonymous sources.Cloud-Based IP Rotation: Some cloud providers offer tools for IP rotation, making it possible to use a large pool of IPs for testing. AWS, GCP, and Azure have features that provide dynamic IPs, making them valuable for simulating a distributed attack surface.

Scenario: You have permission from a client to test their e-commerce website’s defenses. The website blocks repeated attempts from the same IP address to prevent brute force or scraping attacks. You need to test if an attacker could bypass this block.

Step 1: Setting Up Proxy Servers

Choose a Proxy Service: Use a trusted service like Proxyscrape or similar, which provides a pool of proxies. Ensure that the proxies are legal and secure.Configure Your Pentesting Tool: Set up your proxy details in your pentesting tool. Many tools (like Burp Suite or OWASP ZAP) allow you to configure rotating proxies for requests.Automate Proxy Rotation: Use Python or other scripting languages to automate requests, rotating through different proxies.Here’s a simplified Python example:import requests from itertools import cycle # Sample list of proxy addresses proxy_list = [ 'http://proxy1.example.com:8080', 'http://proxy2.example.com:8080', 'http://proxy3.example.com:8080', # Add as many proxies as you need ] # Rotate proxies using cycle proxy_pool = cycle(proxy_list) url = "https://your-target-website.com/login" for i in range(10): # Number of test attempts proxy = next(proxy_pool) print(f"Request #{i+1} using proxy {proxy}") try: response = requests.get(url, proxies={"http": proxy, "https": proxy}) print(response.status_code) except Exception as e: print(f"Failed to connect using {proxy}: {e}")Explanation: The script sends requests to the target website using different proxy IPs each time. The cycle function rotates through proxies, mimicking an attacker’s attempt to avoid IP-based blocks.

Step 2: Analyzing the Results

After running the script, analyze the response status codes. If the website successfully blocks requests despite changing IPs, it may indicate that other detection methods (like behavior-based or request pattern detection) are in place. If all requests go through, it may suggest that the site relies heavily on IP blocking without additional controls.

Once you’ve documented that the IP block can be bypassed, include this finding in your report with recommended mitigations. Effective recommendations include:

Rate Limiting: Suggest implementing rate-limiting mechanisms based on account activity rather than IP alone.Behavioral Analysis: Recommend that the site analyzes request patterns to identify suspicious activity beyond simple IP checks.Multi-Factor Authentication (MFA): Advise implementing MFA for sensitive areas, which adds an additional layer of security.