PublicEnemy is a simple Java based trojan that was found in October 1997. The trojan does modifications to any class files that are located in the same directory from which the trojan is executed. PublicEnemy is a trojan not a virus and thus is unable to spread by infecting other Java applications.
Once detected, the F-Secure security product will automatically disinfect the suspect file by either deleting it or renaming it.
When run, PublicEnemy searches the current directory for .class files, and modifies them damaging the file. The .class files damaged by PublicEnemy sometimes remain operational, but should still be restored from backups or reinstalled.
Being Java based trojan the PublicEnemy is capable of executing in almost any platform that has Java runtime environment installed. The trojan is capable of executing on Windows and Linux platforms and in PDA devices which have Java runtime installed.
PublicEnemy is not capable of spreading and it has not been met in the wild. As such, it can not be considered a realistic threat.
Technical Details: Jarno Niemela, February 2002, F-Secure