In computing, a zombie is a computer connected to the Internet that has been compromised by a hacker via a computer virus, computer worm, or trojan horse program and can be used to perform malicious tasks under the remote direction of the hacker. Zombie computers often coordinate together in a botnet controlled by the hacker, and are used for activities such as spreading e-mail spam and launching distributed denial-of-service attacks (DDoS attacks) against web servers. Most victims are unaware that their computers have become zombies. The concept is similar to the zombie of Haitian Voodoo folklore, which refers to a corpse resurrected by a sorcerer via magic and enslaved to the sorcerer's commands, having no free will of its own.
Advertising
Zombie computers have been used extensively to send
Email spam; as of 2005, an estimated 50–80% of all spam worldwide was sent by zombie computers.
This allows
to avoid detection and presumably reduces their bandwidth costs, since the owners of zombies pay for their own bandwidth. This spam also greatly increases the spread of Trojan horses, as Trojans are not self-replicating. They rely on the movement of e-mails or spam to grow, whereas worms can spread by other means.
For similar reasons, zombies are also used to commit
click fraud against sites displaying
pay-per-click advertising. Others can host
phishing or
money mule recruiting websites.
Distributed denial-of-service attacks
Zombies can be used to conduct distributed denial-of-service (DDoS) attacks, a term which refers to the orchestrated flooding of target websites by large numbers of computers at once. The large number of Internet users making simultaneous requests of a website's server is intended to result in crashing and the prevention of legitimate users from accessing the site.
A variant of this type of flooding is known as distributed degradation-of-service. Committed by "pulsing" zombies, distributed degradation-of-service is the moderated and periodical flooding of websites intended to slow down rather than crash a victim site. The effectiveness of this tactic springs from the fact that intense flooding can be quickly detected and remedied, but pulsing zombie attacks and the resulting slow-down in website access can go unnoticed for months and even years.
The computing facilitated by the Internet of Things (IoT) has been productive for modern-day usage, yet it has played a significant role in the increase in web attacks. The potential of IoT enables every device to communicate efficiently, but this also intensifies the need for policy enforcement regarding security threats. Among these threats, Distributed Denial-of-Service (DDoS) attacks are prevalent. Research has been conducted to study the impact of such attacks on IoT networks and to develop compensating provisions for defense.
Notable incidents of distributed denial- and degradation-of-service attacks in the past include the attack upon the SPEWS service in 2003, and the one against Blue Frog service in 2006. In 2000, several prominent Web sites (Yahoo, eBay, etc.) were clogged to a standstill by a distributed denial of service attack mounted by 'MafiaBoy', a Canadian teenager.
Smartphones
Beginning in July 2009, similar botnet capabilities have also emerged for the growing
smartphone market. Examples include the July 2009 in the "wild" release of the Sexy Space
text message worm, the world's first botnet capable
SMS worm, which targeted the
Symbian operating system in
Nokia smartphones. Later that month, researcher Charlie Miller revealed a proof of concept text message worm for the
iPhone at Black Hat Briefings. Also in July, United Arab Emirates consumers were targeted by the
Etisalat BlackBerry
spyware program. In the 2010s, the security community is divided as to the real world potential of mobile botnets. But in an August 2009 interview with
The New York Times, cyber security consultant
Michael Gregg summarized the issue this way: "We are about at the point with smartphones that we were with desktops in the '80s."
"Malware" has become a serious challenge in smartphones. There are many different kinds, so advances in malware must keep up. One option is the fuzzy logic-based dynamic ensemble (FL-BDE).
See also
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