Just when you thought it was safe to go swimming in the digital waters because you installed anti-virus software and firewalls, the threats get even more complex, rendering your defenses inadequate again.

It's a tough reality for every computer user--as the tools get more efficient, the bad guys simply change their tactics. Every week, new viruses crop up and the old ones can never actually be killed. Worms wiggle into systems, wardrivers jump onto unsecured networks, and phishers have swiped thousands, if not millions, of personal records.

It's comforting to know that there are plenty of security experts toiling to block them, but until they come up with a truly bulletproof security solution, users will just have to be content with staying informed and doing what they can to stay safe. Here are the latest threats to hit the digital world:

evil twin hotspots

In January, researchers at Cranfield University in England reported that malicious hackers could use wireless hotspots to obtain personal and financial information from users by redirecting network traffic to a different hotspot.

Called "evil twin" hotspots, they're created by jamming the connection to a legitimate base station and then either sending traffic to a fraudulent series of sites or stealing information that's input to legitimate sites through keystroke logging programs. Although no actual evil twins have been reported yet, researchers have been encouraging discussion of the vulnerability as a pre-emptive strike against potential attackers.

"We've already seen the issue raised in chat rooms and on news groups," says Dr. Phil Nobles, a wireless Internet and cybercrime expert at Cranfield University. "If we can spread awareness about the problem then maybe for once we can beat hackers at their own game."

Hotspot security has been an oft-discussed topic in security circles, especially as hotspot use grows beyond coffee shops and homes and edges closer to city-wide wireless access. The creation of an evil twin could be disastrous if an attacker chose to target the kind of large hotspots seen at airports or other well-traveled facilities.

"The worst thing about evil twins is that the attackers don't have to be especially clever," says Nobles. "They just have to know how to exploit a flaw. And they can find out from other malicious hackers how to do that."

instant-messaging vulnerabilities

Instant messaging has gone from being a quick way for teens to connect into a nearly full-fledged corporate tool. Although some companies still ban its use, fearing too much personal chatter on the network, many others embrace it as a way for colleagues to get information quickly without a hike down the hallway.

But as IM use grows, the potential for harm does as well. A report released in April from the IMlogic Threat Center--a group made up of vendors Symantec, Sybari, McAfee, IMlogic, Microsoft, AOL, and Yahoo--shows that since the beginning of 2005, IM-related security threats have grown by 271 percent over the previous year. In just the first few months of the year, over 75 new IM and P2P viruses and worms were reported.

The sharp rise should concern every IM user, but businesses should be especially alarmed, notes IMlogic chief technology officer Jon Sakoda. "Some companies still think that IM is safe for employees to use because it sits inside their firewall," he says. "But like e-mail, there's a connection to the network. And whenever you have that, you have the potential for harm."

According to the Threat Center, the top three most detected IM infections in corporate networks were Kelvir, Bropia, and Sumom, and reports of phishing through IM networks are coming in a bit too fast for comfort.

"It'll get worse before it gets better," says Sakoda. "We're already seeing mutations of worms reported just a few months ago." He recommends that companies examine their end-user policies, and revamp IM management standards.

cell phone threats

It was only a matter of time before cell phones and PDAs proved too tempting to pass up for malicious hackers. The cracking of Paris Hilton's Sidekick only emphasized the ease with which information could be obtained, and the vulnerabilities that all wireless users face.

But hacks aren't the only threat for cell phone owners. In late December, code was made publicly available for the Cabir worm, a fast-spreading threat first developed by security researchers. Variants have been sprouting up since then, as virus hobbyists tinker with the makeup of the worm and build in nasty extras that could be coming to a cell phone near you.

"Now that the code is available, we expect that there will be more variants created, and more types of phones targeted," says Mikko Hypponen, security researcher at Finland-based F-Secure. "This is going to be a headache for researchers and users alike."

The Cabir worm targets only Symbian OS-based mobile phones right now, but it's likely that as virus and worm writers play with the code, many more threats will emerge. "Exercise the same caution with your cell as you would with your e-mail," says Hypponen. "And stay tuned."

identity theft tactics

By now, identity theft isn't new. Citibank had a wealth of commercials on the topic, and even mainstream women's magazines have given their readers advice on how to avoid thieves (and get a boyfriend at the same time!). But what many computer users might not know is that the phishing strategies being employed are evolving all the time, making it hard to prevent identity theft through password protection or vigilance over one's accounts.

According to the Anti-Phishing Working Group (APWG), a non-profit organization dedicated to stamping out identity theft, there have been sharp spikes in activity in the last year. In January 2005, reports of phishing e-mails were up 47 percent over just a month earlier. In subsequent months, phishing seemed to decrease, but that's no reason for users to feel a bit more comfortable, says the group's chairman, Dave Jevans.

"When the activity goes down, that's when we're suspicious," he says. "That means the phishers are coming up with something we can't detect yet."

The difficulty, Jevans notes, is that user education simply isn't enough. Phishers have now developed tactics that skip over the user altogether. No longer can attacks be perpetrated by having a user download an .exe file full of spyware. Now, just having an e-mail land in an inbox can infect a system, whether that message is opened or not. At some point, it'll be up to the governments of the world and the anti-virus software makers, rather than individual users, to tackle the problem.

"These are very motivated individuals, and they'll try anything to get money," says Jevans. "Like the authors of any kind of security threat, it's a shame that they use their talents for evil rather than good."