Tricking others into giving out passwords or other sensitive information has a long tradition in the attacker community. Traditionally this activity has been performed through the process of social engineering. In the 1990s, with the increasing growth in interconnected systems and the popularity of the Internet, attackers started to automate this process and attack the mass consumer market. The first systematic research to cover such activity was published in 1998 by Gordon and Chess (Sarah Gordon, David M. Chess: Where There's Smoke, There's Mirrors: The Truth about Trojan Horses on the Internet, presented at the Virus Bulletin Conference in Munich, Germany, October 1998). Gordon and Chess were researching malware on AOL, but they were faced with phishing attempts instead of the expected trojan horse attacks. The term phishing ("password harvesting fishing") describes the fraudulent acquisition, through deception, of sensitive personal information such as passwords and credit card details by masquerading as someone trustworthy with a real need for such information. A phishing message described by Gordon and Chess is shown below:
Early phishing attacks were primarily aimed at gaining access to the victim's AOL accounts, or occasionally at obtaining credit card data for fraudulent purposes (e.g. to make illegal purchases with this information). Often the phishing messages contained a simple ruse to trick unskilled computer users and relied heavily upon the victim’s innate sense of trust in "automated" system functions or (apparent) figures of authority. As demonstrated in the previous example, this could be a story about a broken hardware device or the failure of a database, and most normal system users would take at face value any reasonably official-looking or highly urgent technical request that appeared to offer them assistance. Users were usually prompted to enter sensitive information quickly to avoid a serious problem, for example via the phrase "[...] and re-state your password. Failure to comply will result in immediate account deletion". To avoid potentially dire consequences the victims often complied immediately, unknowingly providing the social engineer with the credentials they required. Anecdotal evidence suggested that the culprits usually were acting alone or in small, unsophisticated groups. Literature often portrays early phishers as adolescents desiring account data for causing mischief and to make long distance phone calls, usually with little high level organisation or malice.
Today, the preferred strategy chosen by phishers is to bulk email their lures to as many end users as possible whilst masquerading as a trusted brand - usually one with whom the phisher hopes there is a chance that the victim already trusts. A request for urgent action is sent, often ironically to protect the user's confidential data from malicious activities, and this spoof email will contain an obscured link to a remote web-page that masquerades as the public web site of the target brand. The phisher hopes that victims will be tricked into submitting their credentials into a fake, but apparently legitimate looking "official" web interface for the trusted brand. Examples of the organisations being targeted by phishers include many well-known banks, credit card companies or well known Internet traders requiring regular payments (e.g. eBay and PayPal). Numerous examples of phishing emails targeting customers can be found at the Anti-Phishing Working Group web site, which has a archive of phishing emails, many of which illustrate the high degree of accuracy with which phishers can trick innocent users into believing they are accessing a legitimate web interface.
Following this brief introduction to the concepts of phishing, we will now review the actual techniques and tools we have captured during phishing attacks observed in the wild. If you are interested in further background on phishing, we have prepared this page of detailed background information.