This virus does not really swap anything, so the alias name is a bit misleading. This boot virus from Israel is unusual in that it does not store the original boot sector anywhere, but instead it just overwrites the original boot sector with a short piece of code to load the rest of the virus, which is stored on one of the last sectors on track 39. A similar method is used by the Alameda virus.
When this virus activates it is said to produce a display of falling letters on the screen - similar to the Cascade virus, but I have not seen this effect yet.
The VSAFE program belonging to Microsoft Antivirus is known to cause false Falling Letters alarms in other antivirus programs. If unsure, delete VSAFE program, reboot and retry.