A Web bot is an automated software program that executes specific commands when it receives the proper input, much like a robot. This automated application is used to perform relatively simple and repetitive online tasks that would otherwise be too difficult or mundane for a human to continuously perform.
Web bots can be used as chat-room moderators or as website advertisers. Web searching bots, known as spiders or crawlers, search the World Wide Web to retrieve documents and record the information found on Web pages. From there, the search bots generate electronic catalogs of the "spidered" sites, making up the index of sites that are delivered as search-engine results.
Bots can also be used by websites to promote shopping deals. In this type of usage, the bot indexes information about a user's visits to pages on the Web.
However, bots can also be used for malicious intents.
Malicious bots are self-propagating blended threats, part malware and part bot. After a malicious bot infects a host, it connects back to a central server or servers that command and control hundreds or thousands of similarly infected computers.
When a group of computers are infected by a malicious bot and work together as one entity, this is known as a botnet. Botnets are used to commit identity theft or launch denial-of-service attacks. This is done by launching broad-based remote attacks against targets.
Bots can log keystrokes or gather passwords and financial information. Other malicious bots can harvest email addresses for spam, scrape content, or manipulate user feedback on sites. Bots have the advantages of worms but are more versatile in their infections, and are often modified within hours of a new exploit.
There are a number of ways to protect yourself against a malicious Web bot. Ensure your operating system is up to date, and that you have updated anti-virus software. Have this software scan emails and downloaded files, and install a firewall.