Yerg, when first run, launches a fake Microsoft Paint application. When this application is run, the worm infects the system and infects many files that you run.
On the 18th of any month, the virus's payload activates. When the virus is run again, it displays a message:
"W32.UFO... The Truth is out there
W32.UFO .. The ALiens are Among us
Flying around the night sky in their UFO
Snatching people up, Shoving things inside there dong
the short little guys with the big black eyes from a galacy far away
and now the UFOs are on your PC!!! many of them, is UFO INvasion
After this message, the worm launches the paint program as usual, but the program changes its icon and the cursor to a UFO. It will also open up http://abduct.com/ in Internet Explorer.