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Viruses, Worms and Trojans

Viruses and Worms

A virus is a small computer programme, often hidden within another programme, so that when the user runs the genuine programme, the virus is able to do whatever the designer intended, such as delete your files. A worm, on the other hand, is more self-contained. It is self-replicating and does not need to be part of any other computer programme or user action to begin its destructive actions.

While viruses and worms are becoming more sophisticated, protecting yourself against them is relatively simple. Follow these tips and you should be able to avoid the worst of cyber nuisances:

  • Install a firewall to prevent viruses and worms getting through. This will block unauthorised access to and from your PC or your network through your computer’s ports. Install a good anti-virus utility.
     
  • Back up your hard drive or your network drive. With CD-writers so readily available and so inexpensive, backing up has become easier and faster than before. Back-up software lets you automate back-ups, making things even easier.
     
  • Get software that takes snapshots of your system. This lets you revert to the latest snapshot when things go wrong, so you can recover from a crash quickly. However, these snapshots are not back-ups of your system or files, so you still need to perform regular daily back-ups.
     
  • Do not open any emails from anyone you do not know. If you run a small business, make this a formal policy. If it’s a potential business partner or someone who really wants to get in touch with you, they will call you over the phone if you don’t reply to their messages.
     
  • Do not download applications or programmes if at all possible. If you do have to download one, scan it with your anti-virus application before executing it.
     
  • Turn your PC off. If you are using an always-on connection such as cable or DSL, turn off your PC when you are not using it. Always-on connections keep the same IP address, which makes it easy to locate your computer on the internet and makes it an easy target. Turning off your PC will prevent people from accessing it over the internet.

Malware and Trojan horse threats

Malware is software written to infect private computers and commit crimes such as fraud and identity theft – it has become big business in the cyber underworld. As a result, if you use a computer for web surfing, shopping, banking, email, instant messaging, and gaming without proper protection, you’re at high risk of being victimised.

By exploiting vulnerabilities in operating systems and browsers, malware can sneak malicious Trojan-horse programmes onto unsecured PCs. Unsuspecting and unprotected users can also download Trojans, thinking they’re legitimate game, music-player, movie, or greeting-card files. Trojans can also lurk in files shared between friends, family, and co-workers using peer-to-peer file-sharing networks.

Trojans have traditionally hidden in worms and viruses spread by email, but they’re increasingly showing up in instant messages and on PDAs and mobiles. Organised crime rings have devised insidious new ways of delivering Trojans, so it’s important to stay informed of the latest tricks. Protection against these multi-faceted attacks requires integrated anti-virus, firewall, and anti-spyware technologies.

What do Trojans do?

Trojans corrupt important files and place adware, spyware, keyloggers, and screen scrapers that can steal personal information. They can also redirect you to fake phishing websites – even when you type valid web addresses (URLs) into your browser.

Trojan programmes are most dangerous because they can create a back door into your computer that gives malicious hackers direct access to your system. Once installed, Trojans can hijack your PC and upload usernames, passwords, credit card numbers, social security numbers, and bank account numbers to specified computers for as long as they remain undetected.

Hackers use chat rooms and peer-to-peer file sharing networks to target and hijack unsecured PCs. Once the Trojan opens a back door, the computer joins hordes of other “zombie” computers that the hacker can control remotely. The hacker can launch Denial of Service (DoS) attacks, generate ad traffic, send out infected software to other vulnerable computers, and pump out spam.

Cyber gangs even rent networks of these zombie computers (a.k.a. bots) by the hour to other criminals for extortion and fraud. Users are rarely aware that their machines have been hijacked, since usually the only indicator is slightly slower performance.

A new trend in malware is to extort money. This ransomware is a Trojan that encrypts a PC’s files or threatens to delete them one by one unless you pay up. After you pay using a money transfer service, the extortionist sends you a special disarming code or decryption application. Hackers also use Trojans to exploit weaknesses in legitimate banking, online bill paying, and e-commerce sites.

How does my PC get a Trojan?

Today, Trojans can be spread by browser drive-bys, where the programme is downloaded in the background when you simply surf to a rigged website. Shell code runs a Trojan that downloads additional payload code over HTTP – various forms of bots, spyware, back doors, and other Trojan programmes. Hackers then send phishing emails to lure you to websites, where unsuspecting victims are tricked into revealing personal information. Hackers can also exploit security weaknesses on sites, and then piggyback their Trojans onto legitimate software to be downloaded by trusting consumers.

Although hackers never stop developing new tricks to commit fraud and steal identities, you can take proactive steps to safeguard your systems. All it takes is a combination of robust security software and a commitment to following basic safety rules. Here are some additional security tips for protecting your computer:

  • Protect your computer with strong security software and make sure to keep it up to date. The McAfee® Internet Security Suite gives trusted PC protection from Trojans, hackers, spyware, and more. Its integrated anti-virus, anti-spyware, firewall, anti-spam, anti-phishing, and back-up technologies work together to combat today’s advanced multi-faceted attacks. It scans disks, email attachments, files downloaded from the web, and documents generated by word-processing and spreadsheet programmes.
     
  • Enable automatic Windows® updates or download Microsoft® updates regularly to keep your operating system patched against known vulnerabilities. Install patches from other software manufacturers as soon as they are distributed. A fully patched computer behind a firewall is the best defense against Trojan and spyware installation.
     
  • Be careful when engaging in peer-to-peer (P2P) file-sharing. Trojans sit within file-sharing programmes waiting to be downloaded. Use the same precautions when downloading shared files that you do for email and IM. Avoid downloading files with the extensions .exe, .scr, .lnk, .bat, .vbs, .dll, .bin, and .cmd. Anti-virus software and a good firewall will protect your system from malicious files.
     
  • Download the latest version of your browser to ensure that it is also fully updated and utilises the latest technologies to identify and filter out phishing sites that can install Trojans.
     
  • Use security precautions for your PDA, mobile phone, and Wi-Fi devices. Trojans arrive as an email/IM attachment, are downloaded from the internet, or are uploaded along with other data from a desktop. Mobile phone viruses are in their infancy, but will become more common as more people buy phones with advanced features. Anti-virus software is available for PDAs and mobiles. McAfee also offers trusted security solutions for Wi-Fi.
     
  • Configure your instant-messaging application correctly. Make sure it does not open automatically when you fire up your computer. Turn off your computer and disconnect the DSL or modem line when you’re not using it. Beware of spam-based phishing schemes – don’t click links in emails or IM.

Above all – don’t panic if you think you have a worm or Trojan. Use your security software to its fullest and use their websites for help on updated risks and solutions.

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