You wouldn’t leave your house unlocked, so why take that chance with your computer? There are a number of different software weapons to use against potential malicious threats. Here are some of those available for free:
Computer viruses, worms and trojan horses are programs designed to damage your computer, corrupt data, or control your PC. Antivirus programs scan everything that goes into your computer – e-mail, discs, attachments – for thousands of known viruses and try to clean up any they find. And remember, installing antivirus software without updating it is like buying home insurance but not making the payments. Be sure to subscribe to an antivirus update service.
| Avast - Since its release, Avast! 4 Home has become one of the most popular full-featured freeware anti-virus applications for Microsoft Windows users. As of March 7, 2008 Avast! (Home version) has had 50 million registered users. |
| AVG - According to their 2007 statistics, AVG has 70 million users (including both the free and commercial versions) and is one of the most downloaded softwares on CNET's Download.com. Simple interface, easy to use and excellent performance put AVG at the top of our list of free versions. |
A firewall puts a protective barrier between your PC and the internet, by inspecting network traffic passing through it, and denying or permitting passage based on a set of rules, somewhat like a security checkpoint that information must pass through before it’s allowed to enter your computer. Firewalls also help make your computer “invisible” to online attackers, viruses and worms.
| ZoneAlarm - freeware firewall including an inbound intrusion detection system, as well as the ability to control which programs can create outbound connections — the latter not available in the Windows XP Service Pack 2 firewall. |
| Comodo - a freeware firewall developed by Comodo Group that provides protection on a Microsoft Windows operating system from both inbound and outbound attacks. |
Spyware programs are stealthy software that installs on your computer without your explicit consent. They can track your Web activity, send annoying pop-up advertising, change your home page and slow your computer to a crawl. More severe types can collect personal information remotely and lead to identity theft.
| Ad-Aware –anti-spyware program developed by Lavasoft that detects and removes spyware or adware on a user's computer. It also detects dialers, Trojans, malware, viruses, bots, rootkits, data-mining, aggressive advertising, parasites, browser hijackers and tracking components. |
| Spybot SD - Spybot - Search & Destroy (often Spybot-S&D) is a popular malware, spyware and adware removal program which scans the computer hard disk and/or RAM for malicious software. Spybot has been applauded for its ease of installation, free updates, and excellent features. |
A botnet (also known as a zombie army) is a number of Internet computers that, although their owners are unaware of it, have been set up to forward transmissions (including spam or viruses) to other computers on the Internet. Most computers compromised in this way are home-based.
| BotHunter - BotHunter is a passive network monitoring tool designed to recognize the communication patterns of malware-infected computers within your network perimeter. Using an advanced infection-dialog-based event correlation engine (patent pending), BotHunter represents the most in-depth network-based malware infection diagnosis system available today. |
| RUBotted - RUBotted monitors for remote command and control (C&C) commands sent from a bot-herder to control your computer. Additionally, RUBotted watches for an array of potentially malicious bot-related activities, including mass mailing - a common activity performed by a bot-infected computer. RUBotted co-exists with your existing AV software, providing advanced bot specific behavior monitoring. RUBotted does not rely on frequent, network intensive updates to ensure your computer’s continued protection. |
A rootkit is a collection of tools (programs) that enable administrator-level access to a computer or computer network. Typically, a cracker installs a rootkit on a computer after first obtaining user-level access, either by exploiting a known vulnerability or cracking a password. Once the rootkit is installed, it allows the attacker to mask intrusion and gain root or privileged access to the computer and, possibly, other machines on the network.
| Panda Anti-Rootkit - Panda Anti-Rootkit (PAR) sifts through the files and Registry items in your computer with a fine-tooth comb, looking for evidence of rootkit activity. It reports its findings in as much detail as you can handle. It distinguishes rootkits it recognizes from unknown ones, but it will wipe out both kinds. |
| Rootkit Revealer - RootkitRevealer is an advanced rootkit detection utility. It runs on Windows NT 4 and higher and its output lists Registry and file system API discrepancies that may indicate the presence of a user-mode or kernel-mode rootkit. RootkitRevealer successfully detects many persistent rootkits |
| ClamXav – based on the open source ClamAV virus scanner. If you're looking for free Mac antivirus software, ClamXav is certainly a virus scanner worth trying. |
| iAntiVirus – protecting against the most nefarious cyber-threats attempting to gain access to your Mac and personal information. Once your computer has been infected, a virus or worm will usually attempt to spread itself to your friends, family and associates by accessing your email contacts and networked PCs. |