A tricky new type of virus is surfacing, using an unfamiliar tactics to gain entry to systems and proliferating across networks. It appears in attachments that are not typically used for viruses, applies a password to avoid detection, and fools victims into entering the password and becoming infected.

Security vendors have suggested that Microsoft's pending antivirus product and upgrades to its next-generation OS (operating system), Windows Vista, won't be enough to guard against rising threats from viruses and criminal malware. In June, Microsoft is set to release Windows OneCare Live, a product that combines antivirus, antispyware, PC tuning and backup capabilities. It will retail for $50 (about £29) per year, a price that puts the product squarely in competition with a range of antivirus software products.

Users and resellers of RAV AntiVirus, which is especially popular on Linux platforms, are in limbo after Microsoft announced plans to buy the RAV technology from GeCAD Software. Microsoft has already said that the RAV product line will be discontinued after it completes acquisition of the technology. GeCAD will, however, continue to support its 10 million users worldwide until the end of their contracts.

CA (Computer Associates) is offering free antivirus software to protect the latest Beta 2.0 release of Microsoft's Vista operating system. Beta testers can now download a one-year trial subscription to CA's eTrust EZ Antivirus software, which the software vendor is billing as the first antivirus product for the next-generation operating system. The Beta 2.0 version of Vista was released on Tuesday. The free subscription gives users access to daily virus updates and web-based technical support. It can be downloaded here.

Symantec last night launched a free public beta for its Norton AntiBot software. Norton AntiBot will analyse your PC's behaviour to identify malware. Norton AntiBot is meant as a supplement to antivirus software, not a replacement. Norton AntiBot benefits from from Symantec's SONAR behavioural scanning technology, but is largely based on existing technology from Sana Security. Symantec's analytic software doesn't use signatures as traditional antivirus products do. Instead, it examines where a program runs from, what Registry changes it makes, what internet sites it may attempt to contact and so on. Symantec says Norton AntiBot won't conflict with other antivirus programs.

Antivirus experts have identified new versions of three major email worms and say that a 'war' between rival virus writers may be to blame for the rash of outbreaks in recent weeks. New versions of the Mydoom, Netsky, and Bagle have all appeared on the internet in the last 48 hours. Antivirus researchers have uncovered text messages in two of the worms that suggest a battle is underway between virus writers, according to antivirus companies.

A bug in the way Norton Antivirus uses the ActiveX programming language could cause serious problems for users of Symantec's products. Yesterday, Symantec patched the flaw warning that a bug in two ActiveX controls used by Norton Antivirus could allow an attacker to run unauthorised software on a victim's computer. Security vendor Secunia rates the threat as "highly critical".

Symantec has patched a widely reported flaw in the English versions of its corporate antivirus software. The flaw, which affects recent versions of its Client Security and Antivirus Corporate Edition products is considered serious, and could be exploited by hackers to run unauthorised software on unpatched PCs.

Antivirus and e-mail security companies are sending out warnings about a new Trojan horse program that they claim is being mass-distributed on the Internet through spam. The program, called Backdoor-CGT, is a new form of a Trojan horse installed after email recipients using Microsoft Outlook follow a weblink embedded in an email message. The Trojan horse is believed to have infected thousands of systems on the Internet since appearing early Tuesday, even though antivirus software and up-to-date versions of Outlook are immune to attack, according to Maksym Schipka, senior antivirus researcher at MessageLabs.

Heard this one before? You must run antivirus software and keep it up to date or else your PC will get infected, you'll lose all your data, and you'll incur the wrath of every email correspondent you unknowingly infect because of your carelessness.