How to Detect Malicious JavaScript Code
The JS language is widely used to develop various web applications. File handling using Javascript plays a crucial role in enhancing the user experience. Still, attackers sometimes use malicious JavaScript Code utilize user's computer resources for illegal activities like stealing sensitive data, gaining illegal access to web applications, crypto-jacking, XSS/js Injection, and stealing cookies.
In some cases, detecting such codes can be challenging as the attackers use obfuscation techniques to hide and modify the codes. In this article, we explore various malicious JavaScript code and methods to guard against them.
Examples of Malicious Code and Adequate Prevention Techniques
1. Code that transfer user input data to a malicious external server:
Explanation:Explanation: This JavaScript code is malicious as it passes sensitive user data like name, password, and email to an external malicious server that an attacker operates.
Here, the method getElementById() is used to retrieve the value of form fields. The open() method assists in establishing a connection to the malicious example server and setRequestHeader() is used to set the request headers with Content-Type header. Eventually, the method send() sends sensitive data to the malicious server.
Detection:
Prefer the following practices:-
-> Keep monitoring the network traffic actively to see if the script is making a request to connect the suspicious servers.
-> Carefully monitor the code that sends data to servers using AJAX requests.
-> Keep a record of third-party scripts to ensure they do not contain any malicious code to pass files illegally to unknown servers.