Malicious software (or malware), often generically called a virus, is computer software which deliberately does something harmful or otherwise abusive to a computer or other digital device. Once downloaded, malware can be passed from one computer to another. Malware is usually downloaded to a computer by hiding inside rogue (and sometimes legitimate) software packages: the Trojan horse (or Trojan).
If an operating system (such as Windows, or Mac OS) gets infected by malware, it could cause the loss of important files; business files, digital music and movies, and pictures could be destroyed by a single infection. The malware may use the infected computer to generate revenue (by displaying advertisements, farming private information, or mining cryptocurrency, for example) or simply cause damage. Malware can also interfere with industrial processes, infrastructure, and other business processes if it has access to related devices. In some other cases, malware has no interest in the host computer, but rather performs various tasks (such as DDoS attacks and spamming) as a bot for the malware publisher.
Infectious Mobile Devices
Android and Apple iOS mobile operating systems are vulnerable to malicious code as well. This can come from PDF files, applications, and a variety of other sources. This malware may affect the infected device, or it could act as an asymptomatic carrier, allowing cybercriminals to access confidential information on in or other devices connected to it, intercept phone conversations or take over other aspects of the infected device.
While Mac malware is scarcer than Windows malware, over the last ten years threats targeting Mac OS X have been on the rise and have become more sophisticated. In addition, Macs can pass on files that contain malware to Windows users. For this reason, a layered approach to security is the best defense, including the use of a firewall and Mac antivirus that detects and stops Windows viruses as well as Mac malware.
Since the iOS is shared across all Mac devices, malware targeting this operating system will sometimes lay dormant until it is connected to another device. For example, one kind of malware will infect an iPhone but remain dormant. Once it is connected to a MacBook (through a wired or wireless connection) it infects that. The malware will also infect any other iOS device available, such as an iPod or iPad. After a time, it can gather information from every device the individual owns, essentially stealing their entire online (and quite possibly real) identity. Such malware is sometimes used by hackers to open a back door into these devices so they can manually lock the entire set of devices and copy everything off of them.
- Credential stealers
- Scareware (rogue software that claims to serve a legitimate purpose, usually pretending to be security software)
Prevention and Recovery
Most malware can be prevented from infecting a computer by following these guidelines:
- Keep the operating system on computer, phone, tablet, etc. and your software updated
- Run an antivirius program on your computer
- Do not connect computers with outdated/unsupported software to the internet
- Only download/install software from trusted sources
- Remove (uninstall) unused software and do not install software that you do not intend to use
- Only visit web sites that you know and trust
- Do not open email attachments unless you know the sender, and can verify that they intended to send you an attachment
- Regularly back up important files and email messages
If you find, or suspect, that you have malware on your computer, you can do one or more of the following (listed in order of how time-consuming they are):
- Run a security scan with your antivirius software
- Run one, or more, of several anti-malware programs
- Reinstall your operating system and software
It may be impossible to guarantee that your computer, phone, or other devices are never compromised with malware. Even trustworthy sources can become unintentional providers of malware. Sometimes security flaws in software allow attackers to gain access to your computer resources, before the software supplier is aware of the flaw. Exploitation of these flaws before the software manufacturer provides patches are called zero-day exploits (or zero-day hacks). Additionally, legitimate software can be compromised either by direct attack on the publisher, or by a supply chain attack (in which, a third party is attacked, leading to the compromise of software downstream).
- malware. Dictionary.com. http://dictionary.reference.com/browse/malware, (accessed: July 13, 2011).
- Definition: Trojan horse, searchsecurity.techtarget.com, (Accessed July 13, 2011).
- Apple Macintoshes Targeted by Porn-Based Computer Virus, FOXNews.com, November 02, 2007.
- The Mac Security Blog. Do You Need an Antivirus for Your Mac? Definitely, Yes., blog.intego.com, December 4, 2008.
- Amy Gahran. iPhone, iPad users: Watch out for malicious PDF files, CNN, July 11, 2011.
- The Mac Security Blog. iOS PDF Vulnerability Creates Security Risks, Allows Easy Jailbreaks, blog.intego.com, July 7, 2011.
- 10 Years of Mac Malware: How OS X Threats Have Evolved (Infographic)