ABSTRACT
A virus that uses advanced stealth is aiming to conceal its existence even from anti-virus software. Viruses that stealth the file size often leave an inconsistency between the size according to the directory entry and the number of elements in the fat chain. Amongst boot sector viruses, Joshi and EDV use advanced stealth techniques. The main enemy of viruses, is the scanner. This is because this is the only tool that many people use. Each virus that uses such a sophisticated decrypter/loader causes an immense amount of work for the scanner vendor, and we are beginning to see some of the vendors give up on these. But some scanners have difficulty detecting all instances of the virus and some scanners give false alarms on some innocent files because of the difficulty in doing it right.
