Computer security, viruses and hacking: a complete guide to protect yourself

La Computer security, viruses and hacking They have become part of everyday life, both for individual users and for companies. We are no longer just talking about isolated failures or minor scares: nowadays, a cyberattack can shut down an entire company, leave thousands of customers without service, or empty a person's bank accounts in a matter of minutes.

At the same time, the The cybercrime economy moves billions of dollars And the attacks are becoming increasingly sophisticated. But the fact that the situation is worrying doesn't mean you're defenseless: by understanding how viruses work, what types of cyberattacks exist, what their real consequences are, and what practical measures you can take, you can greatly reduce the risk of being affected or, at least, limit the damage if something goes wrong.

What is a computer virus and why is it still so dangerous?

A computer virus is, essentially, a malicious program or piece of code Designed to replicate and spread from one device to another without user authorization. Once inside, it can corrupt the system, steal data, encrypt files, consume resources, or even take complete control of the computer.

These viruses are classified according to how they spread, what they aim to achieve, or how they are activatedBroadly speaking, we can find variants designed for espionage, others for economic extortion, and others focused on causing damage or disrupting services, whether for ideological reasons, revenge, or simply for the notoriety of the attacker.

With the rise of the Internet, instant messaging, and cloud applications, Creating and distributing malware is becoming increasingly easy.Languages ​​such as Java, scripts (VBScript, JavaScript, etc.) and office documents with macros allow dangerous instructions to be embedded in seemingly harmless web pages, emails or files, increasing the risk of infection without the user suspecting it.

Main types of viruses and malware you should know

When we talk about malware, we include not only classic viruses, but also a whole family of malicious programs Designed for different purposes. Understanding what each one does helps you identify symptoms, take action, and speak knowledgeably when it comes to protecting your systems.

Among the most prominent threats we find the Trojans, adware, spyware, ransomware, botnets, and keyloggersIn addition to worms, macro viruses, and other more specific code, they all share a common denominator: they install themselves without your consent and operate behind your back.

Classical viruses and historical variants

The oldest viruses ran on specific systems such as VAX/VMSExamples include the Christmas Letter. Its objective was to damage or modify the functioning of the system, at a time when the main means of propagation were floppy disks or other physical media.

Over time, the following emerged macro virusThese malware programs infect popular applications like Word, Excel, and Adobe Acrobat. Cases such as MELISSA and ETHAN demonstrated that simply opening a seemingly normal document is enough to execute the malicious code and send it to new contacts or systems.

They also appeared script virusThese are embedded in HTML pages or emails using JavaScript or VBScript code. When a user visits the page or opens the message, the script runs on their computer and can perform dangerous actions without their knowledge. Examples include AVM, INTERNAL, and the infamous "I LOVE YOU" script.

Trojan horses and back doors

A Trojan horse is a program that presents itself as something useful or innocent, but which It hides malicious functions inside.Once installed, it can open a backdoor for the attacker, allowing them to delete files, log keystrokes, or download more malware. Examples that made history include NetBus and Back Orifice.

The calls rear doors These are sets of instructions embedded in software or operating systems that allow remote access without leaving a trace in audit controls. They are often deliberately created by malicious developers or installed by other malware to ensure long-term control.

Worms and botnets

Worms differ from classical viruses in that They are replicated through networks without requiring the user to run a specific file. They scan routing tables, servers, mailing lists, or stored credentials to copy themselves and spread like a chain reaction.

Its propagation capacity can saturate entire networks (LAN, MAN, etc.), cause system crashes, and open the door to mass infectionsSome historical worms such as SIRCAM, LOVETTER or MAGISTR became famous for spreading through email and other network services.

When many teams are compromised and remotely controlled, they can be integrated into a botnet: a network of zombie devices that the attacker uses to launch spam campaigns, denial-of-service attacks, or cryptocurrency mining, all without the owners of the equipment noticing.

Spyware, adware and keyloggers

El spyware It's designed for espionage: it collects information about your habits, credentials, chats, and banking details, and sends them to a third party without your consent. It can be very discreet and remain installed for months before being detected.

El adware It focuses on displaying intrusive advertising, altering your browser, opening pop-up windows, or redirecting your searches. Although sometimes presented as "legal" or part of free software, it may include malicious components or collect excessive data.

The keyloggers They record everything you type on the keyboard: passwords, emails, messages, web forms… They are tools widely used in credential theft attacks and their danger lies in the fact that they work in the background, without giving visible signs.

Ransomware, logic bombs, and bacteria

El ransomware It encrypts files on your computer or across your entire network and demands a ransom in exchange for the key to recover them. It usually displays a lock screen with payment instructions, often in cryptocurrency. Paying guarantees nothing: you could lose your money and still lose access to your data.

The logic bombs These are fragments of code that remain dormant until a certain condition is met: a specific date (like the infamous Friday the 13th or Michelangelo), a key combination, or a specific system event. At that moment, they activate and execute destructive or sabotaging actions.

The calls bacteria "Fork bombs" are programs that replicate themselves continuously within the same system, consuming memory, CPU, or disk space until the computer becomes unusable. They don't always aim to steal data; sometimes they simply intend to completely lock the machine.

Hoaxes or rumors: disinformation is also a problem

Hoaxes are not viruses in the strict sense, but Yes, they are a threat to digital security Because they spread fear and misinformation, wasting time and resources. They usually arrive via email or social media, warning of supposed "terrible" viruses or urging people to perform absurd actions.

A classic example was the message encouraging people to type “Q33 NY” into Word and change the font to Wingdings, implying it was the flight code of one of the 9/11 planes. The code was fake, but the hoax spread massively, demonstrating how social engineering can exploit curiosity and fear.

How viruses and other malware spread

The routes of transmission have changed over time, but they still exist today. very common propagation channels which should be well controlled if you want to minimize risks.

Among the most common ways malware spreads are the suspicious emails and SMS messagesSoftware downloads, malicious websites, removable devices, and the exploitation of security holes in operating systems and applications.

The emails with suspicious attachments or links They remain a classic: simply opening the file, clicking on a fraudulent link, or enabling macros in a document is enough to start the code running. The same applies to text messages or messaging apps that include shortened links or unknown files.

The external storage devices USB drives, portable hard drives, and memory cards are also a significant source of risk. If you connect an infected USB drive to an unprotected computer, malware can automatically install itself or copy itself to other files.

The downloads from untrusted websitesPirated repositories or "free" installers that include toolbars or additional programs are another common route. These often come bundled with adware or spyware that installs in the background.

Finally, many infections occur by exploiting vulnerabilities in operating systems or programs Outdated. A simple flaw in the browser, a plugin, or the system itself can allow an attacker to execute arbitrary code on your computer simply by visiting a manipulated page.

What is a cyberattack and the most common types

A cyberattack is any deliberate action in which an attacker attempts to compromise confidentiality, integrity, or availability of systems, networks or data. It can be directed against individuals, companies, public institutions or critical infrastructure, and its objectives range from information theft to economic extortion or industrial espionage.

In recent years all kinds of attacks have proliferated, some highly technical and others based primarily on social engineeringThat is, manipulating people so that they themselves unwittingly open the door to the criminal.

Denial of Service (DoS and DDoS) attacks

In a DoS or DDoS attack, the objective is to take a system or website offline saturating their resources (CPU, memory, bandwidth) with malicious traffic. DDoS attacks employ thousands of compromised computers (botnets) that send simultaneous requests, making filtering difficult.

MITM attacks and illegal wiretapping

Attacks Man in the Middle (MITM) These methods involve positioning oneself between two communicating endpoints (for example, your browser and the bank's website) to intercept, modify, or redirect information. Illegal eavesdropping or sniffing relies on capturing network traffic to read unencrypted data.

Identity theft and phishing

Identity theft encompasses everything from classic email phishing This includes more targeted variants such as spear-phishing or whaling. In general phishing, the attacker sends mass messages impersonating banks, well-known platforms, or official organizations to steal credentials.

El spear-phishing It targets specific individuals or companies using personalized information to make the scam more believable. whaling It focuses on senior managers or people with privileged access, in order to obtain large benefits or critical information.

Password and brute force attacks

Password attacks include everything from use of leaked credentials in other breaches (credential stuffing) to the systematic testing of combinations using brute force or dictionaries. If passwords are weak or reused across multiple services, the chances of success skyrocket.

SQL injection, XSS and web attacks

In the attacks of SQL injectionThe attacker introduces malicious commands into forms or URL parameters to manipulate the database behind a web application. They can read, modify, or delete sensitive information.

Attacks Cross-Site Scripting (XSS) They insert scripts into web pages that are then executed by the victims' browsers, allowing them to steal cookies, hijack sessions, or redirect to malicious sites. All of this is part of a broader range of web attacks (CSRF, file uploads, etc.).

Spoofing, session hijacking, and URL interpretation

La DNS spoofing This involves manipulating domain name resolution to redirect the user to a server controlled by the attacker, even if the address they typed is correct. It is a very effective way to steal credentials.

El hijacking of sessions This involves hijacking the session identifier of an already authenticated user (for example, by stealing cookies) to impersonate them. Malicious URL manipulation and similar techniques exploit how browsers and servers process addresses to deceive the user or the system.

Insider threats and malware attacks

Not all attacks come from outside: internal threats (Disgruntled employees, former employees, or collaborators with legitimate access) can leak data, sabotage systems, or steal intellectual property.

The malware attacks They generally combine several techniques: exploiting a vulnerability, executing malicious code, establishing persistence, and from there, moving laterally through the victim's network, escalating privileges and stealing or encrypting information.

Zero-day vulnerabilities: the race between attackers and defenders

A zero-day vulnerability is a security flaw in software, firmware or hardware which doesn't yet have an official patch from the vendor. It may already be publicly known, or only known to researchers and certain groups of attackers, but until there's an update, users are vulnerable.

It's called "day zero" because, from the moment the developer becomes aware of the problem, It has zero days of margin to react before it begins to be actively exploited. When the patch finally appears and is distributed, the vulnerability becomes "known" or "n-day", although it will still be dangerous if the system is not updated.

When attackers create proof-of-concept or working malware that exploits that vulnerability before a solution is available, we call it exploit or zero-day attackIt's a constant race: researchers try to fix it before it's exploited, while cybercriminals try to squeeze every last drop of profit from the vulnerability while it remains open.

The real impact of cyberattacks: recent figures and examples

Cybercrime drives a gigantic parallel economyRecent studies estimate that the global cost of cybercrime will continue to grow at a double-digit rate each year, with losses in the trillions of dollars due to theft, extortion, business disruption, regulatory penalties, and reputational damage.

At an individual level, victims face identity theft, account emptying, blackmail, and leaks of personal dataIn the case of companies, the consequences include production stoppages, intellectual property leaks, customers leaving, and fines for failing to adequately protect information.

In regions like Latin America, a sharp increase in incidents has been detected. In a recent year, Around a third of the cases analyzed involved data leaksand more than a fifth involved direct extortion (often linked to ransomware). Botnets, credential theft, and mass data exfiltration represented similar percentages of the total.

Major data breaches and attacks on well-known companies

One of the most striking cases was the discovery of a gigantic database with some 26.000 billion records The leaked data came from platforms like Twitter, Dropbox, LinkedIn, and many others. It was a file of about 12 terabytes that compiled credentials and data from multiple previous breaches.

This type of build makes it easier for attackers to carry out credential stuffing attacks, targeted phishing, and other large-scale abuses. For users, the lesson is clear: Use unique and strong passwords, and enable two-step authentication. and be especially vigilant about suspicious emails after incidents of this kind.

Another example was the incident that affected Bank of America Following a problem at a technology provider (Infosys McCamish), a security flaw allowed access to the data of more than 57.000 customers, including names, addresses, dates of birth, and social security numbers. A ransomware group known as LockBit claimed responsibility for the attack.

This case highlights the importance of manage risk effectively with external providersConduct regular security audits and clearly define in contracts who is responsible and how in the event of a breach.

Even tech giants like ecosystem They have suffered significant attacks. A breach in their Azure platform compromised the accounts of high-level executives, and a critical vulnerability (CVE-2024-21410) was also discovered in thousands of Exchange servers that allowed for privilege escalation, manipulation of NTLM hashes, and user impersonation.

In the industrial sector, cases like that of VolkswagenThe theft of thousands of documents on electric vehicle technologies and production strategies (allegedly in a context of international espionage) demonstrates that the target is no longer just personal data, but also intellectual property.

And we cannot forget the internal threatsAs happened with Tesla, where former employees leaked the personal information of tens of thousands of workers to a media outlet. Although the data was not published, the mere fact of the leak requires the activation of legal and communication protocols, as well as a review of how access to information is controlled.

Malicious hackers and ethical hackers: two sides of the same coin

The term “hacker” is often used confusingly. Technically, a hacker is someone with high technical skill to explore and modify systemsThis includes both those who break security for criminal purposes and those who do so to improve it.

On one side are the cybercriminalsThese groups form a veritable criminal industry: they sell malware, offer on-demand attack services, resell stolen databases, and extort victims. The cost of their actions is expected to reach astronomical figures in the coming years.

At the other extreme are the ethical hackersThese professionals use their expertise to strengthen security, detect vulnerabilities before others exploit them, and help businesses and law enforcement agencies pursue criminals. Their work includes penetration testing, audits, forensic analysis, and bug bounty programs, among other services.

Even a consumer who Modify your own smartphone to install custom software It technically falls under the umbrella of hacking, even if it's not malicious. The key isn't the label, but the intent and compliance with the law.

How to protect your computer and your business from viruses and hacks

The good news is that, although the risk is never zero, There are many practical measures to reduce the attack surface.The combination of technical tools, safe practices, and an appropriate incident response makes all the difference.

Antimalware and system updates

The first step is to use a Reliable antimalware application and keep it up to date. Windows includes Microsoft Defender, which updates automatically through Windows Update, but you can also opt for reputable third-party solutions. The important thing is to keep real-time protection active and the signature databases up to date.

Just as crucial as antivirus software is Keep your operating system and programs up to dateSecurity updates fix vulnerabilities that attackers could exploit, including known zero-day flaws. While restarting can sometimes be inconvenient, it's one of the best defenses available.

Browser, SmartScreen and pop-up windows

Modern browsers include security features that are worth enabling. Tools such as SmartScreen in Microsoft Edge They help block pages or downloads that have already been categorized as dangerous, showing clear warnings to the user.

Also, use a popup blocker It reduces exposure to malicious ads or scripts that load in pop-up windows. While many pop-ups are just advertising, others may contain unsafe code or lead you to fraudulent websites.

La browser privacy settings It's also key. Limiting what data websites can collect, controlling tracking cookies, and restricting permissions (geolocation, camera, microphone) minimizes the risk of your information being used for aggressive advertising, fraud, or identity theft.

Email, UAC, and tamper protection

Regarding mail, the golden rule is Do not open messages or attachments from unknown sendersAnd don't click on links you weren't expecting, even if the sender seems trustworthy. Phishing attacks are becoming increasingly sophisticated and can convincingly impersonate addresses or signatures.

In Windows, the User Account Control (UAC) User Account Control (UAC) prompts for confirmation when an application attempts to make changes that require administrator privileges. Keeping UAC enabled makes it more difficult for malware to modify critical settings without your knowledge.

Features such as Tamper Protection They prevent unauthorized applications from disabling your antimalware solution or changing security settings. Many viruses try to disable antivirus software to operate freely, so this feature is especially useful.

Specific measures for companies: training and legal response

In the business environment, in addition to technology, the following have enormous weight: staff awarenessTraining employees in detecting suspicious emails, password management, using external devices, and good browsing practices drastically reduces the success rate of many attacks.

It is essential to have a clear and adaptable cybersecurity strategythat covers external and internal risks, defines access controls, establishes procedures for revoking permissions when an employee leaves the company, and includes supplier audits.

When an incident occurs, many victims rush to the scene and They restart or clean the equipment, losing key evidenceIt is preferable to keep records, screenshots, emails, encrypted files and, if possible, make forensic copies so that experts can analyze what happened and the authorities have solid evidence.

In ransomware cases, paying the ransom is rarely a good option. There is no guarantee of data recovery. Furthermore, criminal organizations are being funded. Consulting with cybersecurity specialists and a lawyer allows you to explore technical (backups, public decryption tools, system reconstruction) and legal alternatives to respond without giving in to blackmail.

Specialized law firms and security consultancies can coordinate the technical, legal and communication aspects, file complaints, claim damages and minimize reputational impact, especially when third-party data is involved and data protection regulations must be met.

This whole landscape of malware, vulnerabilities, and cyberattacks demonstrates that cybersecurity is no longer an optional "extra," but a basic requirement for any user and company that wants to continue operating with peace of mind: knowing the types of viruses, how they spread, what techniques attackers use, and what tools we have to defend ourselves transforms a seemingly hostile environment into a manageable scenario, where prevention, constant updates, and rapid reaction make the difference between a simple scare and a major crisis.