This was the subject of a 2003 lawsuit by adware vendor Gator (which has since changed its name to Claria). The lawsuit, aimed at anti-spyware maker PC Pitstop, claimed that calling Gator's product "spyware" amounted to defamation. Following an out-of-court settlement, PC Pitstop no longer calls Gator's product spyware, but still helps people remove it.
"We'll never get a letter from the lawyer of the guy who wrote the Netsky worm saying stop blocking my stuff, but spyware vendors feel they can be as intrusive as they want because you visited the site or downloaded the software," says Hansmann.
Hansmann says Trend Micro has to proceed carefully when defining programs to be blocked or removed. Spyware researchers at Trend Labs have to coordinate with Trend Micro's legal department before including software in a detection database.
Finally, spyware (and adware in particular) is often more difficult to remove than viruses. Many viruses exist as discrete entities on host machines, making them easy to find and delete. Spyware spreads itself throughout a PC, so portions of the program can exist throughout the file system and in dozens or hundreds of registry keys and directories. The result is that anti-spyware engines have to conduct detailed searches and attempt to remove all traces of spyware without affecting the PC's normal operations.
Failure to fully remove the program can affect the PC's performance. That's because spyware often inserts itself into the boot functions of the host PC. If the spyware program has been deleted elsewhere but entries remain in the boot process, the OS may return an error message because it can't find the program to run at startup.
