Skip to main content

Secure Network Architecture Desing

Few days back I was going through an article on "Managing Network Security". Although it was a bit technical, it presented some fundamental idea about designing secure network architecture of an organization. I just picked up few points from the article easy-to-grasp, left the detailed and technical ones.
Design a secure network architecture:

1. Make sure hosts are not permitted to access the Internet directly. They should access
it through content filtering proxies capable of scanning the packets for malicious code. If
they need to be connected by a NAT rule on the firewall, ensure that the necessary network
and security controls (such as desktop firewall, antivirus and antispyware tools) are
present on the host.

2. All emails should pass through a secure mail gateway that is capable of filtering email threats.

3. Implement strong authentication for accessing networked resources.

4. Host hardening lowers the chances of system compromise or exploitation. Stick to best
practices of system installation, followed by hardening and conducting of regular vulnerability
scans. Hardening hosts and network devices directly after installation considerably reduces the attack surface.

5. If your organization uses wireless as a network connectivity option, ensure that proper
security controls are placed to safeguard the flowing of data through a wireless network.
Some of the security measures to be taken are:
a) Secure the wireless access via VPN tunnels or strong encryptions like WPA2.
b) Wireless access points should be hardened and endpoint security measures should be taken.
c) Implement wireless IPS and rogue device detection techniques.

6. Implement a strong password policy in your organization to safeguard online accounts
against password attacks such as brute force, dictionary or hybrid password attacks.

7. Use automated tools to gather network information on a regular basis and analyze them. Create the latest network map based on the information and a list of assets belonging
to your organization. This assists in the detection of rogue devices on wired or wireless
networks. Maintain and update the switch port, router port configuration document. Keep
unused ports disabled on all network points.

8. Use a Security Information and Event Management tool to obtain meaningful security
logs and events correlations. SIEM/SIM tools assist in infrastructure security by providing
important logs to centralized security server and correlate them at that point. It helps IT
security operations personnel be more effective in responding to external and internal

These points figure out an ideal architecture of an oragnization or how it should be.


Popular posts from this blog

Ardilla- New tool for finding SQL Injection and XSS

Three Researchers -- MIT's Adam Kiezun , Stanford's Philip Guo , and Syracuse University's Karthick Jayaraman -- has developed a new tool ' Ardilla ' that automatically finds and exploits SQL injection and cross-site scripting vulnerabilities in Web applications. It creates inputs that pinpoint bugs in Web applications and then generates SQL injection and XSS attacks. But for now Ardilla is for PHP -based Web app only. The researchers say Ardilla found 68 never-before found vulnerabilities in five different PHP applications using the tool -- 23 SQL injection and 45 XSS flaws. More information is awaited. For their attack generation techniques refer to their document at:

File Upload through Null Byte Injection

Sometimes, during file upload we come across situation wherein there would be check on the file extension at the client side as well as server side too. If the application does allow only .jpeg extension to be uploaded, the client side java script checks for the extension of the file before passing the request. We all know that how easily this can be defeated. Some applications, checks for the extension at the server side also. That's not easy to bypass. However there are some ways with which it still can be bypassed. Most of server side scripts are written in high level languages such as Php, Java etc who still use some C/C++ libraries to read the file name and contents. That leads to the problem. In C/C++ a line ends with /00 or which is called Null Byte. So whenever the interpreter sees a null byte at the end of the a string, it stops reading thinking it has reached at the end of the string. This can be used for the bypass. It works for many servers, specially php servers. T

Combining power of Fiddler with Burp

Both are pretty powerful tools when it comes to intercept and modify http communications. But at some point of time, they become even more powerful combo if tied with each other. They complement each other. In a recent pentest I came across a similar situation where in Burp was not able to intercept a specific kind of traffic and Fiddler came to rescue. The application was designed to upload video. The initial communication was straight forward, I mean logging into application, filling up the video details etc. And all these were easily captured by Burp except the point where you hit the Upload Video and it connects to a different server and surprisingly it was not captured by Burp, not sure why, even after repeated attempts. So, I fired Fiddler to see if the it sees this request. But it's a;ways to play with requests using Burp due to it's various functionalities like, Intruder, Repeaters etc. But it was necessary to capture this request in Burp. So the below steps can be