Malware
Viruses E-mail 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 e-mail Can attach to Word documents, spreadsheets –
anything which can have code Famous “boot-sector” virus on floppy disks
E-mail viruses
Programs that are attached to e-mail 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