spambot

A spambot is a program designed to collect e-mail addresses from the Internet in order to build mailing lists for sending unsolicited e-mail, also known as spam. A spambot is a type of web crawler that can gather e-mail addresses from Web sites, newsgroups, special-interest group (SIG) postings, and chat-room conversations. Because e-mail addresses have a distinctive format, spambots are easy to write. A number of legislators in the U.S. are reported to be devising laws that would outlaw the spambot.

A number of programs and approaches have been devised to foil spambots. One such technique is known as address munging, in which an e-mail address is deliberately modified so that a human reader (and/or human-controlled Web browser) can decode it but a spambot cannot. This has led to the evolution of sophisticated spambots that can recover e-mail addresses from character strings that appear to be munged, or rendering the text into a web browser and then scraping the rendered text for email addresses. Alternative transparent techniques include displaying all or part of the e-mail address on a webpage as an image, a text logo shrunken to normal size using inline CSS, or as text with the order of characters jumbled and restoring the order using CSS, where users are then able to see the address. Although these methods combat spambots, they are not compatible with web page accessibility standards and some also disable hyperlink capability - users are not able to click the address to send an email.

The term spambot is sometimes used in reference to a program designed to prevent spam from reaching the subscribers of an Internet service provider (ISP). Such programs are more often called e-mail blockers or filters. Occasionally, such a blocker may inadvertently prevent a legitimate e-mail message from reaching a subscriber. This can be prevented by allowing each subscriber to generate a whitelist, or a list of specific e-mail addresses the blocker should let pass.

Another type of spambot surfs the web, looking for forums to submit, and it submits spam e-mails to these web forums, often with OCR technology to bypass any CAPTCHAs.

There are also spambots used to post spam links to guestbooks, wikis, blogs, forums and any other web forms to boost search engine ranking. This category of spambot has gained considerable notoriety since November of 2006, with the introduction of XRumer, a forum and wiki spambot which can often bypass many of the safeguards administrators use to reduce the amount of spam posted.

See also

• Address munging
• Botnets
• Stopping e-mail abuse

References

• Email Address Harvesting: How Spammers Reap What You Sow by the US FTC

External links

• Botnet discussion mailing list
• Bot-trap - A Bad Web-Robot Blocker
• Fight Spam - Join Byteplant's Spambot Honeypot Project
• How to Block phpbb Spam. (The phpbb spambot honeypot project)
• How to block spambots
• How to detect and ban spambots with iptables
• Reputation services such as TrustedSource tackle the issue
• Spambot Beware! - information on how to avoid, detect, and harass spambots
• Stas Bekman's Article on Botnets and how they are used for spamming
• Stopping Spambots - A Spambot Trap - Using Linux, Apache, mod_perl, Perl, MySQL, iptables and Embperl
• The top 10 spam bot user agents you MUST block. NOW. list of current spambots, harvesters and other bad bots.
• Virus Bulletin's The World of Botnets

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