Beware of Spam

Spam is posting of advertisements, abusive, or unneeded messages . It is generally posted by automated spambots. Spams maybe come to your email in the forms of instant messaging spam, usenet newsgroup spam,web search engine spam, blog spam and mobile phone messaging spam. Spamming is economically viable because advertisers have no operating costs beyond the management of their mailing lists, and it is difficult to hold senders accountable for their mass mailings. Because the barrier to entry is so low, spammers are numerous, and the volume of unsolicited mail has become very high. The costs, such as lost productivity and fraud, are borne by the public and by internet service providers, which add extra capacity to cope with the deluge.

E-mail Spam

E-mail spam is the most common form of internet spamming. It involves sending unsolicited commercial messages to many recipients. Unlike legitimate commercial e-mail, spam is generally sent without the explicit permission of the recipients, and frequently contains various tricks to bypass e-mail filtering. Spammers obtain e-mail addresses by a number of means: addresses from Usenet,postings,listings, or Web pages; guessing common names at known domains (known as a dictionary attack) and "e-pending" or searching for e-mail addresses corresponding to specific persons, such as residents in an area. Spamming is widely reviled, and has been the subject of legislation in many jurisdictions. Many e-mail spammers go to great lengths to conceal the origin of their messages. They might do this by spoofing e-mail addresses (similar to internet protocol spoofing). The spammer will modify the e-mail message so it looks like it is coming from another e-mail address. However, many spammers make it easy for recipients to identify their messages as spam by placing an ad phrase in the field. Spammers try to circumvent the email filters by intentionally misspelling common spam filter trigger words. For example, "viagra" might become "vaigra", or other symbols may be inserted into the word as in "v/i/a/g./r/a". E-mail service providers have begun to use the misspellings themselves as a filtering test.

Spambots are a major producer of e-mail spam. The worst spammers create e-mail viruses that render an unprotected PC a "zombie computer" the zombie will inform a central unit of its existence, and the central unit will command the "zombie" to send a low volume of spam. This allows spammers to send high volumes of e-mail without being caught by their ISPs or being tracked down by antispammers; a low volume of spam is instead sent from many locations simultaneously.

Messaging Spam

Messaging spam, sometimes termed spim (a portmanteau of spam and IM, short for instant messenger), makes use of instant messaging systems, such as AOL instant messenger or ICQ. Many IM systems offer a user directory, including demographic information that allows an advertiser to gather the information, sign on to the system, and send unsolicited messages. To send instant messages to millions of users requires scriptable software and the recipients' IM usernames. Spammers have similarly targeted Internet Relay Chat channels, using IRC bots that join channels and bombard them with advertising. Messenger service spam has lent itself to spammer use in a particularly circular scheme. In many cases, messenger spammers send messages to vulnerable Windows machines consisting of text like "Annoyed by these messages? Visit this site." The link leads to a Web site where, for a fee, users are told how to disable the Windows messenger service. Though the messenger service is easily disabled for free, the scam works because it creates a perceived need and offers a solution. Often the only "annoying messages" the user receives through Messenger are ads to disable Messenger itself.

Chat Spam

Chat spam can occur in any live chat environment like IRC and in-game multiplayer chat of online games. It consists of repeating the same word or sentence many times to get attention or to interfere with normal operations. It is generally considered very rude and may lead to swift exclusion of the user from the used chat service by the owners or moderators. The application of the name "Spam" to unwanted communication originates in Chat-room spam. Specifically, it was developed in the chat-rooms of People-Link in the early 1980’s as a technique for getting rid of unwelcome newcomers. When someone would enter a chat-room full of friends who were in mid-conversation, and the newcomer tried to turn the conversation in an unwelcome direction (usually trolling for cybersex), two veteran members of the room would begin typing in the Monty Python “Spam” routine at high speed. They would fill the screen with “Spam Spam Spam eggs Spam Spam and Spam” etc, and make all other communication impossible. The other members of the room would just wait quietly until the newcomer got disgusted and moved on to a different room.

Spam Targeting Search Engines

Spamdexing(a portmanteauof spamming and indexing) refers to the practice on the World Wide Web of modifying HTML pages to increase the chances of them being placed high on search engine relevancy lists. It uses unethical means, "black hat SEO techniques." to unfairly increase the rank of sites in search engines. Many modern search engines modified their search algorithms to try to exclude web pages utilizing spamdexing tactics.

Blog, Wiki and Guestbook Spam

Blog spam, or "blam" for short is spamming on weblogs. In 2003, this type of spam took advantage of the open nature of comments in the blogging software movable type by repeatedly placing comments to various blog posts that provided nothing more than a link to the spammer's commercial web site. Similar attacks are often performed against Wikis and guestbooks, both of which accept user contributions.

from: Wikipedia