Input validation is a much less effective method in this case because attackers can go around it using clever tricks. This makes it impossible for malicious users to include remote files. Remote file inclusion RFI is a serious web vulnerability. If an RFI vulnerability exists in a website or web application, an attacker can include malicious external files that are later run by this website or web application.
Also read about a related vulnerability — local file inclusion LFI. RFI can be very dangerous. Potential consequences range from sensitive information disclosure and cross-site scripting XSS to remote code execution code injection and, as a final result, full system compromise. Read more about remote code execution attacks that may be the result of RFI vulnerabilities.
The most efficient way to detect RFI is by using an automated vulnerability scanner such as Acunetix. You can of course detect such vulnerabilities through manual penetration testing but it takes a lot more time and resources. Learn how vulnerability scanning and penetration testing should be used together.
As a result, sanitization should only be considered a supplement to a dedicated security solution. These inputs include:.
In the process of sanitization, input fields should be checked against a whitelist allowed character set instead of a blacklist disallowed malicious characters. Generally speaking, blacklist validation is considered a weak solution, as attackers can choose to supply input in a different format, such as encoded or hexadecimal formats.
Client-side validation functions, having the benefit of reducing processing overhead, are also vulnerable to attacks by proxy tools. Finally, you should consider restricting execution permission for the upload directories and maintain a whitelist of allowable file types for example PDF, DOC, JPG, etc.
As mentioned, input sanitization and proper file management practices are almost never sufficient on their own, even if they effectively minimize the risk of RFI. This is important, as many attacks succeed as a result of a false sense of security, which is encouraged by DIY practices.
Imperva offers a number of solutions to combat RFI attacks. First among them is our Web Application Firewall WAF , which monitors user inputs and filters out malicious requests using a combination of signature, behavioral and reputation-based security heuristics. The WAF is deployed as a secure proxy and, as such, blocks RFI attempts at the edge of the server—before they can interact with your web application.
Additionally, in the event that your application is compromised prior to activating our services, Imperva offers backdoor protection —a reactive measure that detects and quarantines backdoors already installed on your server. Finally, our crowdsourcing technology allows us to maintain a continually-updated database of compromised domains that serve as centralized distribution points for malware injected during RFI attacks.
Monitoring these domains provides additional accuracy to our filtering process, while also enabling rapid response against emerging RFI attack vectors, including zero-day RFI assaults. Remote file inclusion RFI What is RFI Remote file inclusion RFI is an attack targeting vulnerabilities in web applications that dynamically reference external scripts.
The graph below illustrates the typical flow of a RFI attack. Cybersecurity Trends and Predictions Register Now. The attacker will be able to include a local file, but in a typical RFI attack, the path can be changed to a file that exists on a server they control.
In this way, malicious code can be easily written inside a file, without the need to poison logs or inject code inside the webserver. The impact of an exploited remote file inclusion RFI vulnerability may differ based on the execution permissions of the webserver user.
Any included source code can be executed by the webserver along with the privileges of the existing web server user, allowing the execution of arbitrary code. Full system compromise is also possible in instances when the webserver user has administrative privileges. RFI is considered to be a common vulnerability that permits the attacker to upload malicious code or files on a server or website.
All website hacking attacks are not exactly about SQL injection. By using RFI, you will be able to literally deface the websites, attain access to the server and practically play anything with the server. It is an established fact that finding an RFI vulnerability is the very first step to hack a website or server. Hence, get started by:.
Go to Google and search for the following query. If you are already aware of an RFI vulnerable website, you need not find it via Google. This can take place as the site may be automatically adding the. If it automatically adds something in the lines of. To prevent RFI vulnerability exploitation, ensure that you disable the remote inclusion feature in your programming languages' configuration, especially if you do not need it.
You should also verify user input before passing it to an Include function. The most preferred way to do this is with a whitelist of permitted files. You can minimize the risk of RFI attacks via proper input validation and sanitization. However, keep in mind that it is important to avoid the misconception that all user inputs can be entirely sanitized.
Consequently, sanitization should only be considered as a supplement to a genuine security solution. These inputs include:. During the sanitization process, input fields will have to be checked against a whitelist instead of a blacklist. Blacklist validation is generally considered to be a weak solution because attackers can choose to supply input in a different format, such as hexadecimal or encoded formats.
It is also good to apply output validation mechanisms on the server end. Client-side validation functions, holding the benefit of reducing processing overhead, are also considered to be vulnerable to attacks by proxy tools.
As a final tip, always consider restricting the execution of permission for the upload directories and make sure to maintain a whitelist of allowable file types besides restricting uploaded file sizes.
Web Application Firewall. Our malware detection scanning, preventive methods and removal enables you to take a proactive approach to protect the business and brand reputation from malware attacks and infections.
Comodo cWatch Web can identify malware, provide the tools and methods to remove it, and help to prevent future malware attacks at the edge before it hits the network, included as a paid member. Already have an cWatch account? Sign in here. Our exclusive C. While anomaly detection to identify changes associated with the network safety.
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