Customers and users of online applications or websites are the most typical victims of malicious scripts since they have no way of knowing that dangerous script exists in these websites or applications and believe the business with which they are dealing is secure and safe.

Malicious scripts are codes used on websites to exploit their vulnerabilities and system flaws in order to upload malware like viruses, adware, worms, backdoor attacks, Trojan horses, bots, logic bombs, and spyware. Users can be harmed by them visiting compromised websites or clicking on a broken email link or attachment to introduce malicious code onto their machines.

Working of Malicious Script:

Malicious scripts are mainly carried out to execute malware attacks. The threat actors can hack into an ordinarily trustworthy website and inject their own code inside it either to steal their personal data or install malware into their system.

For example, a reputed e-commerce website called “Shoppinger” where users make online payments are hacked and the hackers inject their own code such that when a user clicks on “Buy Now”, two things could happen, he could be either redirected to the hackers’ website which is identical to the Shoppinger’s payment page and the user fills in their Bank PIN which gets revealed to the attackers, or a harmful software can start to download in the user’s system which without a firewall or an antivirus cannot be detected.

This is how, hackers can infect clients’ computers with harmful malware by exploiting one of the many flaws in browsers, operating systems, third-party programs, or the website itself that allow them to introduce exploits in the first place.

The hackers can easily read the original code to mix their own code into it without any inconvenience because before the machine-readable code is executed, the human-readable code like Java, Javascript, and machine-readable Python is processed line by line by the system. Thus the computer being unnotified of any attack executes the command once the interpreter converts it to machine-readable code.

Types of Malicious Script Attacks:

1. Cross-site scripting (XSS): Cross-site scripting, termed (XSS) is one of the most popular malicious script attacks. XSS can be used to inject client-side harmful scripts into web pages that are being viewed by other users. A cross-site scripting weakness could be used by an attacker to get around access restrictions like the same-origin policy. 

Symantec shared that XSS attacks are extremely easy to exploit, 21 cyber issues of every 25 attacks happening until 2007 were carried out using online cross-site scripting attacks.

XSS attacks are more sensitive to websites that require very high security and authentication system in order to protect the sensitive information being shared among the users with each other. So in such cases, XSS can implement minor breaches if not major attacks.

When an attacker stores malicious script in the data provided by a website’s search or contact form, this is known as reflected cross-site scripting. A reflected XSS attack example would be that a hacker while analyzing a website notices that a user fillable information which gets stored in the website server can allow tags and thus fills Javascript malicious code to attack users who click on the attacker’s profile page where the malicious code submitted by them is written.

2. HTML injection: Injection of Hypertext Markup Language (HTML) is a technique where the website users’ security is breached by taking advantage of vulnerable sites of the webpages in that website by entering unjustifiable input data to modify that web page. The web page is modified by code written in HTML when programs are unsuccessful in checking user-provided data, in order to change website content that is presented to other users.

A specially constructed query can result in the inclusion of attacker-controlled HTML elements in the web page, changing the way application material is exposed to the web.

3. Skimming: Skimming is the kind of cyber attack in which the hacker tries to steal the financial particulars of the users using an otherwise legitimate e-commerce website or online payment website where they need to fill in their bank information like UPI ID, bank number, account number, CVV, PINs.

The malicious software used in skimming attacks is called Magecart, that is why the other name of skimming attacks is called Magecart Attacks. Magecart is also the name of the hackers or group of cybercriminals who participate in skimming attacks to steal financial information. This stolen information of the users is then sold in the illegal markets for further exploitation.

To protect from skimming attacks, as a user, use payment apps/websites which securely store card information so that they are not regularly used while making payments, as an owner of payment apps, regularly audit your code.

4. Malvertising: Malvertising is an acronym for malicious advertising, a relatively new hacking technique in which hackers insert dangerous malware into digital adverts. The software frequently redirects users to bogus websites. It might be challenging for both internet users and publishers to discover these infected ads because they are regularly displayed to consumers through authorized advertising networks. Multiple redirections between different servers happen after a person clicks on an ad. Attackers take advantage of this intricacy to deliver harmful content to publishers and ad networks in unexpected areas.

 Protection from Malicious Scripts:

To avoid such attacks, users must remember that there is no such thing as a completely safe website on the internet, therefore they must take efforts to protect themselves. It is necessary to upgrade the operating system and software that are most vulnerable to these attacks in order to minimize them (namely browsers, Flash Player, and Java). However, having a security solution that can detect these dangerous scripts – not only those written in JavaScript but also those written in PowerShell and other scripting languages – isn’t always enough.

Allowing risky code to run in client programs like web browsers is the greatest approach to prevent being attacked in the first place. You can avoid this by adopting a range of scenario-specific strategies, such as a guide against cross-site scripting attacks, avoiding compromised code libraries, and web server security standards.