👉 Overview
👀 What ?
Pentesting SMB (Server Message Block), which is a protocol primarily for file sharing, printer sharing, and access to serial ports and miscellaneous communications between nodes on a network, is a critical aspect of cybersecurity testing. The 139,445 ports are often associated with the SMB protocol, and understanding how to pentest these can provide valuable insights into potential vulnerabilities.
🧐 Why ?
The importance of pentesting SMB lies in its widespread use in corporate networks. SMB, being a network protocol, has been a popular target for attackers. If a malicious actor gains access to an organization's SMB, it could lead to data theft, disruption of services, or even a full-scale breach. Therefore, understanding how to perform a penetration test on SMB is vital for identifying and addressing potential security weaknesses before they can be exploited.
⛏️ How ?
Pentesting SMB involves several steps. Firstly, identify open SMB ports in your network using tools like Nmap. Secondly, enumerate SMB to gather information such as a list of shared resources, user names, and group names using tools like Enum4linux. Thirdly, attempt to exploit known vulnerabilities, such as SMB Relay attacks. Tools such as Metasploit can be used for this purpose. Always remember to follow ethical guidelines during a penetration test.
⏳ When ?
Pentesting SMB became a regular practice with the rise of cyber threats and the realization of SMB's vulnerabilities. It became particularly important after the WannaCry ransomware attack in 2017, which exploited a weakness in the SMB protocol.
⚙️ Technical Explanations
SMB operates over two ports: 139 and 445. Port 139 is typically used for NetBIOS name resolution, while port 445 is used for SMB over TCP. During pentesting, we first scan these ports for any open services. Enumeration follows where we probe further into the system to collect data, which could be used in exploiting the system. Several tools like Nmap, SMBMap, and SMBClient can be used for this purpose. The final step is exploitation, where we try to exploit known vulnerabilities in the system. One common attack is the man-in-the-middle attack known as SMB Relay, where an attacker captures an SMB session, modifies it, and forwards it to another host while impersonating a legitimate user.