There is no antivirus software that catches all viruses. Even the best security applications do not have a perfect detection rate which means that it can happen that a virus slips past by them and infects the computer system.
Even if they detect all known viruses, which they don't, they might not detect new malicious code.
There are a few options to cope with this problem. From sandboxing and using virtual machines, to running regular checks with third-party antivirus programs to improve the likelihood of detection.
Some users run multiple tools on their system, but that can cause a number of issues as it may result in conflicts that can lead to a system becoming inoperable or extremely unreliable or slow.
Dr. Web CureIt
Dr. Web CureIt is a third-party antivirus programs that can be used to scan a Windows operating system without causing any conflicts with installed security solutions.
The program requires no installation and can be run right from the location it was downloaded to.
Note that it has a size of about 150 Megabyte, and that it uses random file names to prevent that malware blocks the execution of it on a system.
Dr. Web CureIt can detect and remove viruses, rootkits, trojans and other malicious or infected files on compatible systems.
Three types of scans are available: A quick, full and custom scan. A quick scan will only scan the most important locations of the Windows operating system including boot sectors, startup objects, the Windows system folder and the user documents folders.
It is usually recommended to perform a full scan instead to make sure all files and locations are scanned. While it takes longer to complete, it is the only way to ensure that the system is indeed clean and not infected by malware.
Objects that have been found as malicious during the scan can be cured, renamed, moved or deleted from within the program's interface.
Dr.Web CureIt is an interesting program for users who want to quickly scan their computer system without having to install yet another antivirus software. It is a second opinion scanner that does not get in the way, but can be very useful if you want to verify the findings -- or non-findings -- of installed security software.
The product is quite renowned for its detection and cleaning capabilities, and a solid on demand scanner to catch malicious software that regular antivirus misses.
The only downside are the popups that are displayed by the program that advertise the commercial version of the program and that it sends anonymous usage statistics to the makers.