Malware is a malicious software that is unknowingly purchased, downloaded, or installed. The use of malware to exploit network vulnerabilities continue to rise hitting an all time high of 812.67 million infected devices.
The most common types of malware include:
- Viruses
- Keyloggers
- Worms
- Trojans
- Ransomware
- Logic Bombs
- Bots/Botnets
- Keyloggers
- Adware & Spyware
- Rootkits
Malware is often deployed through phishing emails or socially engineered attacks (which we will discuss later). In short, threat actors (the bad guys) send links to websites or embed attachments within the email itself. The malware then runs a malicious code to gain entry into your network.
Viruses
A virus is the most common type of malware attack. In order for a virus to infect a system it requires a user to click or copy it to media or a host. Most viruses self-replicate without the knowledge of the user. These viruses can be spread from one system to another via email, instant messaging, website downloads, removable media (USB), and network connections.
Some file types are more susceptible to virus infections – .doc/docx, .exe, .html, .xls/.xlsx, .zip. Viruses typically remain dormant until it has spread on to a network or a number of devices before delivering the payload.
Keyloggers
Keylogging, or keyboard capturing, logs a user’s keystrokes and sends data to the threat actor. Users are typically unaware that their actions are being monitored. While there are use cases for employers using keyloggers to track employee activity, they’re mostly used to steal passwords or sensitive data. Keyloggers can be a physical wire discreetly connected to a peripheral like a keyboard, or installed by a Trojan.
Worms
Similar to a virus, a worm can also self-replicate and spread full copies and segments of itself via network connections, email attachments, and instant messages. Unlike viruses, however, a worm does not require a host program in order to run, self-replicate, and propagate. Worms are commonly used against email servers, web servers, and database servers. Once infected, worms spread quickly over the internet and computer networks.
Trojan Horses
Trojan horse programs are malware that is disguised as legitimate software. A Trojan horse program will hide on your computer until it’s called upon. When activated, Trojans can allow threat actors to spy on you, steal your sensitive data, and gain backdoor access to your system.
Trojans are commonly downloaded through email attachments, website downloads, and instant messages. Social engineering tactics are typically deployed to trick users into loading and executing Trojans on their systems. Unlike computer viruses and worms, Trojans are not able to self-replicate.
Ransomware / Crypto-Malware
Ransomware is a type of malware designed to lock users out of their system or deny access to data until a ransom is paid. Crypto-Malware is a type of ransomware that encrypts user files and requires payment within a time frame and often through a digital currency like Bitcoin.
Ransomware attacks can have a devastating impact. For example, current estimates of the Baltimore ransomware attack is up to $18 million in damages. Like viruses, worms, and Trojans, ransomware is delivered via email attachments, website downloads, and instant messages and spread through phishing emails or infected websites. There is no guarantee that paying the ransom will grant access to your files/data and the recovery process can be difficult and expensive.
Logic Bombs
Logic bombs are a type of malware that will only activate when triggered, such as on a specific date/time or on the 25th logon to an account. Viruses and worms often contain logic bombs to deliver its payload (malicious code) at a pre-defined time or when another condition is met.
The damage caused by logic bombs vary from changing bytes of data to making hard drives unreadable. Antivirus software can detect the most common types of logic bombs when they’re executed. However, until they do, logic bombs can lie dormant on a system for weeks, months, or years.
Bots/Botnets
Botnet, short for roBOT NETwork, is a group of bots, which are any type of computer system attached to a network whose security has been compromised. They are typically controlled remotely.
The Mirai botnet was able to gain control of internet of things (IoT) connected devices like your DVR, home printer as well as smart appliances by entering the default username and password that the devices shipped with. The threat actors deployed a DDoS (distributed denial of service) attack by sending large amounts of data at a website hosting company, causing many popular websites to be taken offline.
Adware & Spyware
Adware and Spyware are both unwanted software. Adware is designed to serve advertisements on screens within a web browser. It’s usually quietly installed in the background when downloading a program without your knowledge or permission. While harmless, adware can be annoying for the user.
Spyware, on the other hand, is a type of malware designed to gain access and damage your computer. Spyware, on the other hand, collects user’s information such as habits, browsing history, and personal identification information. Attackers then sell your data to advertisers or data firms, capture your bank account information, or steal your personal identity. Spyware is often downloaded in a software bundle or from file-sharing-sites.
Rootkits
Rootkits are a back door program that allows a threat actor to maintain command and control over a computer without the user knowing. This access can potentially result in full control over the targeted system. The controller can then log files, spy on the owner’s usage, execute files and change system configurations remotely.
While traditionally deployed using Trojan horse attacks, it’s becoming more common in trusted applications. Some antivirus software can detect rootkits, however, they are difficult to clean from a system. In most castes, it’s best to remove the rootkit and rebuild the compromised system.
