Whatever the reason for a malicious cyber-attack, whether it be for financial gain, espionage or just for the sheer hell of it, companies must protect against unwarranted incursion into their system. However, with these new methods of attack it is becoming increasingly difficult to ensure that they don’t penetrate computer systems because when they do the effects can range from the defacement of websites to the fraudulent extortion of vast sums of money. The recent attacks Bluesquare are a case in point of how far hackers are willing to take extortion.
So what can be done to ensure a sufficient level of protection against attack from these sources? Clearly, patching is not working because of the speed with which these attacks strike and propagate to other computers. A PC worm may be similar to a virus, in that it spreads from computer to computer, but where the worm differs is the speed of self-propagation. Worms use the basic transport mechanisms of any computer or network to spread as quickly as possible, allowing attackers to take control of systems and execute malicious behaviour. Normally this happens before a patch has had a chance to be created, let alone implemented, meaning worms can march through the globe’s computer systems at an incredible rate. Sasser and Blaster are examples of how devastating they can be.
The traditional signature-based approach still favoured by many companies to detect malicious attacks is based on patches, updated at regular intervals, and is inherently reactionary and out-of-date to stop zero-day attacks. Until a worm or Trojan is known and a signature created and updated, the antivirus program cannot provide protection against the malicious code as it does not recognise it as a threat. Even when the signature for these is known, if a worm executes itself from memory and not from the file system, a lot of antivirus programs are not capable of protecting a system from it. A lot of this type of code also hides in less accessed system directories which will only be processed by AV software during a full file scan. Which means that in most cases AV will help clean up the worm only after it infects the machine or network, and probably infected many other systems.
So how do we protect against this new breed of attack that is seemingly marching through unprepared systems? Intrusion detection software does not rely on signatures but highlights when malicious code has accessed critical areas such as memory, file system, OS, registry and applications. However closer to the mark this is it is still a case of closing the gate once the horse has bolted – surely prevention is better than cure. This is where Host Intrusion Prevention Software (HIPS) enters the fray.