Unfortunately, it may happen occasionally that the antivirus installed in your computer with its latest updates is incapable of detecting a new virus, worm or a Trojan. Sadly but true: no antivirus protection software gives you a 100% guarantee of complete security. If your computer does get infected, you need to determine the fact of infection, identify the infected file and send it to the vendor whose product missed the malicious program and failed to protect your computer.
However, users on their own are typically unable to detect that their computer got infected unless aided by antivirus solutions. Many worms and Trojans typically do not reveal their presence in any way. By way of exception, some Trojans do inform the user directly that their computer has been infected – they may encrypt the user’s personal files so as to demand a ransom for the decryption utility. However, a Trojan typically installs itself secretly in the system, often employs special disguising methods and also covertly does its activity. So, the fact of infection can be detected by indirect evidence only.
Symptoms of infection
An increase in the outgoing web traffic is the general indication of an infection; this applies to both individual computers and corporate networks. If no users are working in the Internet in a specific time period (e.g. at night), but the web traffic continues, this could mean that somebody or someone else is active on the system, and most probably that is a malicious activity. In a firewall is configured in the system, attempts by unknown applications to establish Internet connections may be indicative of an infection. Numerous advertisement windows popping up while visiting web-sites may signal that an adware in present in the system. If a computer freezes or crashes frequently, this may be also related to a malware activity. Such malfunctions are more often accounted for by hardware or software malfunctions rather than a virus activity. However, if similar symptoms simultaneously occur on multiple or numerous computers on the network, accompanied by a dramatic increase in the internal traffic, this is very likely caused by a network worm or a backdoor Trojan spreading across the network.
An infection may be also indirectly evidenced by non-computer related symptoms, such as bills for telephone calls that nobody made or SMS messages that nobody sent. Such facts may indicate that a phone Trojan is active in the computer or the cell phone. If unauthorized access has been gained to your personal bank account or your credit card has bee used without your authorization, this may signal that a spyware has intruded into your system.
