Malicious Code: Definition and Examples

From trying to gain access to personal information to stealing vital business data, threat actors use malicious code and malware to breach and damage systems across the world. Malicious code refers to any code intended to cause undesired effects within a system.

A malicious actor might use code such as spyware or a trojan horse with the intent to cause harm. Identifying and removing this malicious code from your system is vital for security and stability, and strategies exist to help avoid malicious code in the first place. So what does malicious code mean, and how do you defend against it?

Definition of Malicious Code

Malicious code is a term for code — whether it be part of a script or embedded in a software system — designed to cause damage, security breaches or other threats to application security. An important part of this definition is intent. Nonmalicious attacks do happen and are often accidental or due to negligence. Malware can infect a network from a phishing email, for example.

Malicious code comes in many forms:

  • Trojans
  • Viruses
  • worms
  • Ransomware
  • Backdoor attacks

Malicious code can cause major disruptions on your computer and in your network. Files can be deleted, a hacker might gain control of your computer, passwords may become compromised and daily operations can be halted. These dangers make compliance with the NIST SP security control guidelines vitally important in the United States. The code inserted inside your system gives a bad actor access. The damage caused depends on the type of malicious code used and the attacker’s intent.

Examples of Malicious Code

Malicious code has been around as long as computers, though its form has changed over the years. In the 1980s, malicious code came in the form of file infectors spread by using a floppy disk. With the standardization of technology came an increase in instances of malicious code and malware, which was accelerated by broad adoption of Web 2.0.

Different types of malicious code attack systems in different ways:

  • Backdoor attacks are designed to use a virus or technology to bypass all security measures to gain unauthorized access to a system or network.
  • Scripting attacks inject malicious script into trusted websites, usually as browser side script via a web application. TweetDeck suffered a scripting attack that caused all who fell victim to retweet it, resulting in quick and expansive spread.
  • Worms are a type of virus designed to self-replicate and spread across computers in a network. In 2004 the authors of MyDoom, Bagle and Netsky spread email worms to each other, eventually leading to better email scanning implementation.
  • A trojan horse is malware that disguises itself as legitimate code or software. When inside a network, attackers have the same access that a legitimate user does and can make changes to files and data.
  • Spyware is designed to stay hidden so that attackers can collect information and transmit data from a computer’s hard drive. This also gives attackers access to things like screen grabbing, keylogging and camera control.
  • Ransomware is malicious software that blocks access to a system until money is paid to the attacker.

Attackers use different methods depending on the type of malicious code used. Some of these methods include the following:

  • Social engineering. This is accomplished through human interaction and involves manipulating people into giving away sensitive information, like the answers to security questions.
  • Malicious scripts. These are fragments of code or malicious files hidden within legitimate websites or third-party scripts.
  • Vulnerability exploitation. This is used to make a network or system susceptible to malware and further attack with inserted malicious code.
  • Supply chain exploits. These target the relationship between an organization and the external parties it works with for supply or sales.

Each of these malicious attacks can wreak havoc in your system just by gaining access to a single computer. Whether they come in the form of a malware attack or a computer virus, detecting and removing this malicious code needs to happen fast.

Detection and Removal of Malicious Code

There are several common warning signs that your computer or network has fallen victim to malicious code or malware.

  • Your computer slows down significantly overnight.
  • Computer programs frequently begin crashing, even after restarting.
  • Pop-ups spamming your screen often indicate there is spyware on a computer.
  • Having access to network activity while offline is a sign of a virus.
  • You experience a sudden increase or decrease in your hard drive’s capacity.
  • Your contacts might be receiving strange messages from your email.

Once you’ve seen these signs, you can be sure you already have malicious code in your system. There are types of antivirus software and antimalware to find and remove this malicious code. Removing this code involves manually disconnecting from the internet, entering safe mode, and deleting temporary files.

With that done, you can run a malware scanner and begin to recover your systems. Recovery from a malicious attack can cost your business significant resources. Read on for steps you can take to avoid malicious code altogether.

Avoidance of Malicious Code

Malicious software comes in myriad forms, and keeping your business safe can be an uphill battle. Avoiding and safeguarding against malicious code is a continuous process, but there are steps you can take to ensure the safety of your business:

  • Use white box testing to check the security of your system from attacks with a full understanding of how your system functions.
  • Implement employee security training across your company.
  • Use antiphishing solutions to block phishing attempts from attackers posing as trusted entities.
  • Purchase and maintain antivirus and antimalware software.
  • Use secure web browsing features.
  • Frequently scan for software vulnerability.
  • Frequently patch and update software.
  • Use zero-trust access management, which treats each access attempt as untrusted until successful identity verification.

Using these different security strategies in tandem can do a lot to keep your business safe from malicious code. Although using antivirus software is often the best way to defend against malicious attacks, including other practices can improve your business’s safety.

Malicious Code Protection with CrowdStrike

The use of information technology is a requirement for modern businesses. The use of software, code, and even email can lead to security vulnerabilities. Attackers use malicious code and malware to take advantage of this vulnerability, but you can take steps to stop them.

CrowdStrike offers a variety of products that combine high-end technology with a human touch. The CrowdStrike Falcon® platform delivers cloud-native, next-generation endpoint protection via a single lightweight agent and offers an array of complementary prevention and detection methods. Learn more here.

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