A quick & dirty guide to malware (part 2: viruses)

A dialogue screen shown by Virus:W32/Duts.A

This is the second posting in a three-part series covering common threats a user may encounter.

This series serves as a rough and ready guide, highlighting key features and trends relevant to most users.

The One That Left

Last week I spoke of Trojans, Viruses and Worms as The Big Three. I lied a bit, though. Viruses – as a distinct malware type – probably shouldn’t be on that list any more.

Viruses have always loomed large in users’ minds as the poster child of malicious programs – heck, we even call it the anti-virus industry. In the last 10 years or so however, the number of virus infections has nosedived; our Labs, which once dealt with viruses routinely, now sees a proper virus infection about once or twice a month. Today when people talk of ‘viruses’, more often than not what they’re describing is technically a trojan or a worm, and they’re using the term in a general, ‘any malware will do’ kind of way.

That’s not to say viruses are extinct; we still receive a small, if persistent, number of queries about viruses. This may be because many businesses, households and users (both in developed countries and in recently connected developing ones) still use old, out-dated, unpatched machines or programs, or haven’t yet developed a security-conscious habits.

Whatever the case, virus infections will probably still cling on to life for a weary day after, so let’s take a look at them.

Highlights of a virus

Definition of a virus given by Merriam-Webster online dictionary

The Merriam-Webster online dictionary’s bare-bones definition of a computer virus touches on important elements most users should know, so I’ll just elaborate a bit more on some key concepts:

“usually hidden within another seemingly innocuous program”

Last week I compared a virus to a parasite, because not only does it ‘hide’ in another program, but also depends on its host to function. For the virus to run, the unsuspecting user must actively launch the infected program, which in turn launches the virus.

For this reason, virus writers usually create viruses that infect executable files (especially popular programs such as word processors or media files), which have a higher chance of being run; programs with files that get passed around a lot are extra attractive, since they can affect even more potential victims.

A good example is the Microsoft Office suite which, with their huge community of business and personal users, used to be a popular target for macro viruses. We still see queries related to this virus type, though thankfully far less than previously.

“Produces copies of itself and inserts them into other programs”

If you think of the common cold virus spreading from one person to another, you’ll have a pretty good idea of why this behavior can be so damaging. When a infected file is executed, it searches for and infects new files; if the newly infected files are launched, they find and infect new files in turn, like some evil Multi-Level Marketing operation. At worst, this pattern can lead to every targeted file on the system being infected.

“Usually performs a malicious action”

The damage a virus can do by replicating and infecting new files is bad enough; its payload, a completely separate set of nasty actions, can be worse. The range of actions a virus can take is huge – connecting to a remote site, changing the desktop wallpaper, displaying silly notification messages, deleting data files…it really just depends on the virus author’s imagination and programming skills.

If you’re lucky, they’re not that good and you get failed viruses like Virus:W32/Stardust; if they’re good, then you get really nasty beasts like Virus:W32/Virut or Virus:W32/Sality.AA (one of the few viruses we still find regularly active).

Appending, prepending, cavity…who cares?

A dialogue screen shown by Virus:W32/ZMK

With thousands of unique viruses out in the wild, antivirus companies find it necessary to divide them into sub-types. Unlike trojans though, viruses don’t fall into neat categories reflecting their actions; instead, they naturally fall into groupings based on technical differences in the way they infect a file – which is  basically gobbledeegook to a user not interested in detailed analysis.

Gnerally, viruses can be divided into two groups – system infectors and file infectors. The majority of viruses are the latter and infect programs or data files. System infectors on the other hand write their malicious code to specific, critical sections of the hard disk containing the operating system, so that while the OS is running its normal routines, it’s also unintentionally executing the virus code.

Fortunately, for most users a virus’s classification is largely academic. For better or for worse, the sheer variety of possible effects each unique virus can have on a file or system makes it more practical to take each virus on a case by case basis.

Back to what’s important – why should the user  care?

So let’s go back to the original question that sparked off this series: do you really need to know if it’s a virus – as opposed to, say, a trojan or worm – infecting your computer?

Well, it helps to know because the two malware types tend affect your data and computer in different ways. As a (very) general rule, trojan infections is more about data theft and loss of control over the computer; virus infections tend to result in software disruptions or damage.

Trojans may copy and steal your data, but they don’t usually destroy the data file itself; they may stop programs from running but they don’t destroy the program. A virus on the other hand, insert its own code into a program or data file, and depending on how it does so, may either leave the host completely unharmed and functional, slightly disrupted, or completely non-functional.

Another difference between trojans and viruses that really affects the user involves disinfection. For one thing, a trojan is usually a single, discrete program – getting rid of it tends to be fairly simple, a matter of removing the malicious file and its residuals (registry keys, processes, icons, etc). Removing the trojan also generally doesn’t affect the integrity of other files on the computer.

Viruses are far more nebulous by design – they can be present in multiple files, in different locations. Identifying a virus-infected file may require scanning the entire computer to be sure every affected file is caught. Removing malicious code from an infected file or – if it can’t be saved, deleting the infected file entirely – can also be problematic if the damaged data is important or the program is a critical system component.

And this doesn’t even take into account the virus’s payload, which can produce a whole other set of worries.

If you’re still interested

Still, there is a ray of hope. If current malware trends persist, we may soon see adware or backdoors promoted to being the newest member of The Big Three, and viruses – as a distinct malware type – can finally be relegated to joining 3½” floppy disks in Computer Hell.

In the meantime, here’s some links to other, more in-depth resources on viruses:

Or partially available on Google Books:

  • “Elements of Computer Security” by David Salomon
  • “Cybercrimes: A Multidisciplinary Analysis” by Sumit Ghosh

Next

Coming soon – Worms!

More posts from this topic

trust, internet, internet of things

A Brief History of the Trusted Internet

By Allen Scott, managing director of F-Secure UK and Ireland The internet and the industry which surrounds it is at a tipping point. The scramble to dominate in emerging product and service markets has led many organisations to lose sight of what the Internet should be. If things continue on this downward moral trajectory, we run the risk of breaching the rights of every person who uses it. As a general rule of thumb, violating customers and prospects is not a wise sales strategy. This is why the Trusted Internet is so important now, in 2015, to stem the tide. Half the world away The internet has morphed from a military funded academic computer network into the World Wide Web into what we know today. It has created new industries and billionaire business owners. It has made the world smaller by connecting people who would never otherwise have interacted. It has helped every person by making their life a little easier – from keeping in touch with family to being the number one resource for research on any given subject. It is hard to imagine life without it. Of course, not everyone is online…yet. Figures vary, but it is generally accepted that approximately 3 billion people are now connected to the internet. That is 42% of the world’s population. By 2018, it is estimated that half of the world’s population will be online. That means that every other person could have their human right to privacy (Article 12 of the Declaration of Human Rights) violated. It is unacceptable because it is avoidable. Personal data – the ultimate renewable resource The internet is now an extension of mankind. It is our marvellous creation and we are growing more and more dependent on it. The problem is that it is turning into a Frankenstein’s monster. We are so consumed with whether something (such as tracking people’s movements online) is possible, that the industry has forgotten to ask themselves whether they should. Morality has been pushed aside in the race to gain more personal data, for knowledge is power. Don’t believe how valuable data is? Just take a look at Google. A giant of the internet, it made over £11 billion in profit last year. Not bad for a company which gives away its services for free. Google collects so much data on its users that it is the fourth largest manufacturer of servers in the world. It doesn’t even sell servers! Personal data is big business. Advertisers pay a lot of money for profiles on people. What people like, where they live, who they are likely to vote for, whether they are left-handed – some marketing companies claim to have up to 1,500 points of interest on each individual’s profile. Are all of these ‘interesting points’ something which those people are happy to have shared? I doubt it.  What about the Internet of Things Next up is the Internet of Things (IoT). A concept whereby a vast number of objects, from toasters to bridges, will be connected to the internet where they will share the data they collect. The benefits of this emerging network is that analysis of the data will lead to efficiencies and will make life easier still for people. For example, I could combine the data collected from my smartphone pedometer, my diet app and my watch’s heart monitor to analyse my health and make informed improvements. So far, so good. The IoT waters get a little murkier when you start asking who else has access to that data about me. Maybe I don’t mind if my doctor sees it, but I’m not comfortable with marketing companies or health insurers seeing that data. It’s private. We are fortunate that we are still in the fledgling stage of the IoT and have the opportunity to shape how it impacts our private lives. This is a relatively small window in which to act though, so we must be outspoken in order to protect people’s civil liberties. The ethical solution The next stage of internet development needs to be the Trusted Internet. People have the right to privacy online and it is entirely possible. Not every business and organisation online is part of the data-collecting frenzy. Some, like F-Secure, simply don’t care what you want to look up in a search engine or which websites you visit (unless they are malicious, of course!). We believe that your data is exactly that – yours. Until now, the internet has developed a taste for the free in people. Users have been reluctant to pay for services which they could get for free elsewhere. But now people are realising that when they don’t pay for the product, they are the product. With F-Secure, our customers are just that – customers. Being the customer, their data is their own. Our job is to protect them and their data. We believe that the internet should be a place for people to learn and interact. There shouldn’t be a price on this in the form of our privacy. If there should be a price, it should be monetary, so that people have the chance to buy the services they wish to use, rather than gaining access to services in exchange for personal information. I would happily pay to use Google, Facebook, LinkedIn or one of the many other sites which stakes claim to me when I sign up. We are the generation which created the internet. Let’s not be the generation which disposed of decency, respect and privacy too. [Image by Timo Arnall | Flickr]

Feb 27, 2015
Apple

Which operating system is the most secure? Four points to remember.

No, you are almost certainly wrong if you tried to guess. A recent study shows that products from Apple actually are at the top when counting vulnerabilities, and that means at the bottom security-wise. Just counting vulnerabilities is not a very scientific way to measure security, and there is a debate over how to interpret the figures. But this is anyway a welcome eye-opener that helps kill old myths. Apple did for a long time stubbornly deny security problems and their marketing succeeded in building an image of security. Meanwhile Windows was the biggest and most malware-targeted system. Microsoft rolled up the sleeves and fought at the frontline against viruses and vulnerabilities. Their reputation suffered but Microsoft gradually improved in security and built an efficient process for patching security holes. Microsoft had what is most important in security, the right attitude. Apple didn’t and the recent vulnerability study shows the result. Here’s four points for people who want to select a secure operating system. Forget reputation when thinking security. Windows used to be bad and nobody really cared to attack Apple’s computers before they became popular. The old belief that Windows is unsafe and Apple is safe is just a myth nowadays. There is malware on almost all commonly used platforms. Windows Phone is the only exception with practically zero risk. Windows and Android are the most common systems and malware authors are targeting them most. So the need for an anti-malware product is naturally bigger on these systems. But the so called antivirus products of today are actually broad security suites. They protect against spam and harmful web sites too, just to mention some examples. So changes are that you want a security product anyway even if your system isn’t one of the main malware targets. So which system is most secure? It’s the one that is patched regularly. All the major systems, Windows, OS X and Linux have sufficient security for a normal private user. But they will also all become unsafe if the security updates are neglected. So security is not really a selection criteria for ordinary people. Mobile devices, phones and tablets, generally have a more modern systems architecture and a safer software distribution process. Do you have to use a desktop or laptop, or can you switch to a tablet? Dumping the big old-school devices is a way to improve security. Could it work for you? So all this really boils down to the fact that you can select any operating system you like and still be reasonable safe. There are some differences though, but it is more about old-school versus new-school devices. Not about Apple versus Microsoft versus Linux. Also remember that your own behavior affects security more than your choice of device, and that you never are 100% safe no matter what you do.   Safe surfing, Micke   Added February 27th. Yes, this controversy study has indeed stirred a heated debate, which isn’t surprising at all. Here’s an article defending Apple. It has flaws and represent a very limited view on security, but one of its important points still stands. If someone still thinks Apple is immortal and invincible, it’s time to wake up. And naturally that this whole debate is totally meaningless for ordinary users. Just keep patching what you have and you will be fine. :) Thanks to Jussi (and others) for feedback.  

Feb 26, 2015
BY 
NSA, GCHQ, listening, mobile calls, privacy

Is the NSA listening to your mobile calls? Maybe. Here’s what you can do about it.​

The newest leak from Edward Snowden may be coming at a terrible time for the Obama White House but it's not particularly shocking news to security experts. The Intercept's report about the "Great SIM Heist" reveals American and British spies stole the keys that are "used to protect the privacy of cellphone communications across the globe" from Gemalto, the world's largest manufacturer of SIM cards. It goes on to report that "With these stolen encryption keys, intelligence agencies can monitor mobile communications without seeking or receiving approval from telecom companies and foreign governments," which sidesteps the needs for legal warrants that should be the foundation of ethical law enforcement. While this is certainly troubling and speaks to the agencies wanton regard for privacy and some amateurish procedures being used to transport keys, it likely won't alter the security landscape much. "The best summary is that an already unreliable communication method became even more unreliable," F-Secure Labs Senior Researcher Jarno Niemela, the holder of 20 security-related patents, explained. "Nobody in their right minds would assume GSM  [Global System for Mobile Communications --the digital cellular network used by mobile phones] to be private in the first place," he said. "Phone networks have never been really designed with privacy in mind." Mobile operators are much more concerned with being able to prevent their customers from avoiding billing. While a scope of such a breach does seem huge, Jarno points we're not sure how many of the billions of cards manufactured by Gemalto may be affected. Keys sent to and from operators via without encryption in email or via FTP servers that were not properly secured are almost certainly compromised. But according to The Intercept, GCHQ also penetrated “authentication servers,” which allow it to "decrypt data and voice communications between a targeted individual’s phone and his or her telecom provider’s network" regardless who made the cards. With the cracked keys, users' calls would be vulnerable but likely only in a limited manner. "I am told that these keys only expose the encryption and authentication between the mobile device and the local cell tower," F-Secure Security Advisor David Perry explained. "This means that the NSA or (whoever else) would have to be locally located within radio range of your phone." So could the NSA or GCHQ be listening to your calls without a warrant? Maybe. Here's what you can do about it. Add a layer of encryption of your own to any device you use to communicate. A VPN like our Freedome will protect your data traffic. This would not, however, protect your voice calls. "Maybe it’s time to stop making 'traditional' mobile phones calls," F-Secure Labs Senior Researcher Timo Hirvonen suggests. "Install Freedome, and start making your calls with apps like Signal." [Image by Julian Carvajal | Flickr]

Feb 23, 2015
BY