Malware  Viruses  Virus  Worms  Trojan Horses  Spyware –Keystroke Loggers  Adware

Viruses  Segments of programs that attach to other programs  When an “infected” program is run, the virus is run  The virus seeks uninfected software and infects it  Viruses can be spread to other computers through shared media or  Can attach to Word documents, spreadsheets – anything which can have code  Famous “boot-sector” virus on floppy disks

viruses  Programs that are attached to messages  When run attach themselves to programs  May use address book to send messages to others using victim's return address  May look like image files or text documents

Virus Defenses  Anti-virus software  Can check against a list of virus “signatures”  Can look for suspicious activity  Must be updated regularly  Don't run programs from untrusted sources  Digital signatures  Shrink-wrapped software is not immune to viruses  Informed users

Worms  Program that propagate themselves through a network  When a computer is infected, the program runs and seeks out other computes to infect  Often exploits bugs in software, especially network and web applications  May use password attacks  Famous example: Morris worm of 1998

Worm Defenses  Keep software up-to-date, especially with security patches  Firewall  Monitoring software  Use secure passwords  Informed users

Trojan Horse  A program that appears to do one thing, but really does another  May do both – legitimate and illegitimate functions  Often found in games from untrusted sources Defenses:  Don't download from untrusted sources  Use source code

Spyware  Programs that spy on you  May collect personal information  Can be used for identity theft  Keystroke loggers monitor whatever is typed on the keyboard  Information is sent via the internet to hacker's machine

Warheads  Once control is gained of a computer, there are various malicious tasks that can be done:  botnets  steal personal information  change information  shut down virus protection and other safety features  allow remote access to computer  damage hardware