According to IBM, the average data breach cost in 2022 was $4.35 million globally and $9.44 million in the United States. This includes expenses for responding to the breach, lost revenue, downtime, and reputational damage. Cybersecurity has progressed. However, it has done so at a relatively slower pace. But one of the evolved techniques that are helping fight this menace is banner grabbing. It is a widely used technique for security testing and vulnerability assessment, But, it can also be exploited by malicious actors. This comprehensive guide covers all aspects of this technique. It includes its various types, tools, and ways to protect your system from potential attacks.
What is Banner Grabbing?
It is a method used by security teams and hackers to gain information about network computer systems and services by running on open ports. A banner is a piece of information displayed by a host that provides details about the service or system, such as its software version, operating system, and other facts. This text contained in a banner can help identify the software name, software version numbers, and operating systems running on network hosts, which can then be used to find out the vulnerabilities in the network.
This technique can be practiced manually or automatically using tools such as Nmap, Netcat, Nikro, cURL, and Wget. Running a banner-grabbing attack can be useful for security testing and vulnerability assessment. This is because it helps identify vulnerable and insecure applications that can compromise and exploit the target system.
Types of Banner Grabbing
Active Banner Grabbing
Here, attackers send packets to a remote host and analyze the response data. This attack involves establishing a Transmission Control Protocol (TCP) or similar connection between an origin and remote host. It is one of the most widely-used techniques. However, it is also a risky approach as such attempts can be easily detected by Intrusion Detection Systems (IDS).
Passive Banner Grabbing
This method allows attackers to capture information without sending any requests or traffic to the system. Hence, there is no risk detection. It involves deploying malware and software as a gateway to prevent a direct connection. Also, it entails using third-party network tools and services, such as Shodan, search engines, or traffic sniffing, to gather and analyze packets to determine the software and versions running on the target server.
Banner Grabbing Impact
It can provide information for identifying vulnerabilities in a system and determining potential avenues for attack. This data can be useful for security testing and vulnerability assessment. However, it can also be leveraged by malicious players to obtain unauthorized access to sensitive information. Such information can create network security breaches and cause serious damage to the target’s business operations. For instance, data breaches can lead to intellectual property theft, It can also lead to confidential information leaks, financial loss, and reputation damage. Moreover, it sometimes destroys databases and livelihoods.
Features of Banner Grabbing
- This technique can be completed either manually or with the help of Open Source Intelligence (OSINT) tools that automate the process
- To obtain banner information, the attacker needs to choose a website that displays banners from affiliate sites and then follow the banner link to reach the site served by the affiliate website
- It can be used in ethical hacking to help identify potential vulnerabilities in a target system
- This method can help extract system information by analyzing the customizable text-based welcome displays, known as banners, that are displayed by network hosts
How to Prevent Banner Grabbing
Here are some steps to prevent banner grabbing attacks on a system:
- Remove or modify any banners that contain sensitive information about a system, such as software and version numbers
- Configure the network host’s application or operating system to disable banners or remove sensitive information from external sources
- Disable any unused services on the system that could potentially provide banner information
- Keep the system and software updated with the latest security patches and updates to reduce the risk of vulnerabilities
- Change the default behavior of the server’s banner to hide any version information
- Customize the banners to display a warning message to potential hackers. This indicates that the system is being monitored to deter further attacks
Banner Grabbing Vs Fingerprinting
Banner grabbing and fingerprinting are used to gather information about a target system. Fingerprinting is a type of penetration testing method that aims to obtain comprehensive configuration details of a system. These include the application software technology, cluster architecture, network topology, database version, and host OS platform. The objective of fingerprinting is to obtain the digital signature and detailed information about the system. Banner grabbing, however, is a simpler technique. It involves collecting information from the banners displayed by network hosts. The goal here is to reveal insecure and vulnerable applications and determine potential methods for an attack.
Banner Grabbing Tools
- Telnet: A widely-used cross-platform client which provides a command-line interface that allows users to interact with remote services and systems
- Netcat: One of the most popular and oldest tools for network exploration, administration, and security testing on Unix and Linux systems
- Wget: A great tool that leads users to remote banners or local servers and utilizes a simple script to eliminate expected output and display HTTP server headers
- Nmap: A simple and effective tool designed to establish a connection to an open TCP port on a target system and quickly retrieve details provided by the listening service
- Whatweb: A tool that identifies websites and allows hackers and security analysts to capture the banner of web applications by revealing server information such as IP, operating system, and version
Is Banner Grabbing Illegal?
Banner grabbing is a legal method that is commonly used in ethical hacking to test networks and security. However, it can also be used to gain unauthorized access to a system or to conduct malicious activities, which are illegal and considered a cybercrime. It is crucial to use banner-grabbing methods ethically and legally, such as for security testing or vulnerability assessment with the owner’s consent.
To conclude, while banner grabbing can be a useful tool for security testing and vulnerability assessment, it can also be misused for malicious purposes. As cybercrimes continue to rise, it becomes necessary to stay informed and educated about cybersecurity. To learn more, consider exploring the online cybersecurity courses offered by Emeritus, taught by leading industry experts.
By Krati Joshi
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