From Wikipedia, the free encyclopedia
In computing, phishing is a criminal activity using social engineering techniques. Phishers attempt to fraudulently acquire sensitive information, such as passwords and credit card details, by masquerading as a trustworthy person or business in an electronic communication. Phishing is typically carried out using email or an instant message, although phone contact has been used as well. Attempts to deal with the growing number of reported phishing incidents include legislation, user training, and technical measures.
The first recorded mention of phishing is on the alt.online-service.america-online Usenet newsgroup on January 2, 1996, although the term may have appeared even earlier in the print edition of the hacker magazine 2600. The term phishing is a variant of fishing, probably influenced by phreaking, and alludes to the use of increasingly sophisticated lures to "fish" for users' financial information and passwords. The word may also be linked to leetspeak, in which ph is a common substitution for f. The popular theory that it is a portmanteau of password harvesting is an example of folk etymology.
Early phishing on AOL
Those who would later phish on AOL during the 1990s originally used fake, algorithmically generated credit card numbers to create accounts on AOL, which could last weeks or even months. After AOL brought in measures in late 1995 to prevent this, early AOL crackers resorted to phishing for legitimate accounts.
Phishing on AOL was closely associated with the warez community that exchanged pirated software. A phisher might pose as an AOL staff member and send an instant message to a potential victim, asking him to reveal his password. In order to lure the victim into giving up sensitive information the message might include text such as "verify your account" or "confirm billing information". Once the victim had submitted his password, the attacker could access and use the victim's account for criminal purposes, such as spamming. Both phishing and warezing on AOL generally required custom-written programs, such as AOHell. Phishing became so prevalent on AOL that they added a line on all instant messages stating: "no one working at AOL will ask for your password or billing information".
After 1997, AOL's policy enforcement with respect to phishing and warez became stricter and forced pirated software off AOL servers. AOL simultaneously developed a system to promptly deactivate accounts involved in phishing, often before the victims could respond. The shutting down of the warez scene on AOL caused most phishers to leave the service, and many phishers — often young teens — grew out of the habit.
Recent phishing attempts
More recent phishing attempts have targeted the customers of banks and online payment services. E-mails supposedly from the Internal Revenue Service have also been used to glean sensitive data from U.S. taxpayers. While the first such examples were sent indiscriminately in the hope of finding a customer of a given bank or service, recent research has shown that phishers may in principle be able to establish what bank a potential victim has a relationship with, and then send an appropriate spoofed email to this victim.. Targeted versions of phishing have been termed spear phishing. Social networking sites are also a target of phishing, since the personal details in such sites can be used in identity theft. Experiments show a success rate of over 70% for phishing attacks on social networks. In late 2006 a computer worm took over pages on MySpace and altered links to direct surfers to websites designed to steal login details.
Most methods of phishing use some form of technical deception designed to make a link in an email (and the spoofed website it leads to) appear to belong to the spoofed organization. Misspelled URLs or the use of subdomains are common tricks used by phishers, such as this example URL, http://www.yourbank.com.example.com/. Another common trick is to make the anchor text for a link appear to be a valid URL when the link actually goes to the phishers' site.
An old method of spoofing links used links containing the @ symbol, originally intended as a way to include a username and password in a web link (contrary to the standard). For example, the link http://email@example.com/ might deceive a casual observer into believing that the link will open a page on www.google.com, whereas the link actually directs the browser to a page on members.tripod.com, using a username of www.google.com: the page opens normally, regardless of the username supplied. Such URLs were disabled in Internet Explorer, while the Mozilla and Opera web browsers opted to present a warning message and give users the option of continuing to the site or cancelling.
A further problem with URLs has been found in the handling of Internationalized domain names (IDN) in web browsers, that might allow visually identical web addresses to lead to different, possibly malicious, websites. Despite the publicity surrounding the flaw, known as IDN spoofing or a homograph attack, no known phishing attacks have yet taken advantage of it. Phishers have taken advantage of a similar risk, using open URL redirectors on the websites of trusted organizations to disguise malicious URLs with a trusted domain. 
In another popular method of phishing, an attacker uses a trusted website's own scripts against the victim. These types of attacks (known as cross-site scripting) are particularly problematic, because they direct the user to sign in at their bank or service's own web page, where everything from the web address to the security certificates appears correct. In reality, the link to the website is crafted to carry out the attack, although it is very difficult to spot without specialist knowledge. Just such a flaw was used in 2006 against PayPal.
In another attack, malicious intruders invaded servers of the web hosting company. The intruders then modified the banks' real home pages on the hosting company's servers so that web traffic to the trusted bank sites was redirected to false web pages that looked nearly identical to those under the intruders' control. When unwary bank customers visited the legitimate home pages, the customers were redirected to phony web pages right from the banks' web hosting company's own servers. Once bank customers landed at the false web pages, the intruders were presented with opportunities to steal passwords and other personal information entered by unsuspecting customers. The ruse lasted as long as 90 minutes, with the attack affecting the web hosting company's 600 bank clients in varying degrees. In the meantime, the web hosting company recognized irregularities in web traffic patterns of the bank sites, and the web hosting company shut down its web hosting servers to thwart the attack.
Some security experts characterized this attack as a security breach, since phishing typically involves enticement of an unsuspecting person to visit a rogue site by way an embedded link in a spoofed e-mail message. In this case, the attack took a different spin, with breakdown in security occurring right at the source -- servers operated by the web hosting company. However, security experts found that banks were not entirely blameless in this episode, too, since this type of attack could have been averted had the banks used two-way authentication to establish and prove the identities of the bank and user.
Not all phishing attacks require a fake website. In an incident in 2006, messages that claimed to be from a bank told users to dial a phone number regarding a problem with their bank account. Once the phone number (owned by the phisher, and provided by a Voice over IP provider) was dialed, prompts told users to enter their account numbers and PIN.
PayPal phishing example
In an example PayPal phish (right), spelling mistakes in the email and the presence of an IP address in the link (visible in the tooltip under the yellow box) are both clues that this is a phishing attempt. Another giveaway is the lack of a personal greeting, although the presence of personal details is not a guarantee of legitimacy.
SouthTrust Bank example
In this second example, targeted at SouthTrust Bank users, the phisher has used an image to make it harder for anti-phishing filters to detect by scanning for text commonly used in phishing emails.
From: SouthTrust <firstname.lastname@example.org>
Subject: SouthTrust Bank: Important Notification
Date: Thu, 16 Jun 2005 23:56:30 -0200 (22:56 BRT)
Damage caused by phishing
The damage caused by phishing ranges from loss of access to email to substantial financial loss. This style of identity theft is becoming more popular, because of the ease with which unsuspecting people often divulge personal information to phishers, including credit card numbers, social security numbers, and mothers' maiden names. There are also fears that identity thieves can obtain some such information simply by accessing public records.
Once this information is acquired, the phishers may use a person's details to create fake accounts in a victim's name, ruin a victim's credit, or even prevent victims from accessing their own accounts.
It is estimated that between May 2004 and May 2005, approximately 1.2 million computer users in the United States suffered losses caused by phishing, totaling approximately $929 million USD. U.S. businesses lose an estimated $2 billion USD a year as their clients become victims. In the United Kingdom losses from web banking fraud — mostly from phishing — almost doubled to £23.2m in 2005, from £12.2m in 2004, while 1 in 20 users claimed to have lost out to phishing in 2005.
A bank in Europe has initially refused to cover losses suffered by its customers, in a move that is backed by the UK banking body APACS' stance that "customers must also take sensible precautions...so that they are not vulnerable to the criminal."
There are several different techniques to combat phishing, including legislation and technology created specifically to protect against phishing.
One strategy for combating phishing is to train users to deal with phishing attempts. User education can be promising, especially where training provides direct feedback to the user on his success (or otherwise).  One newer phishing tactic, which uses phishing emails targeted at a specific company, known as spear phishing, has been harnessed to train users at various locations, including West Point Military Academy. In a June 2004 experiment with spear phishing, 80% of 500 West Point cadets who were sent a fake email were tricked into revealing personal information.
Users who are contacted about an account needing to be "verified" can take steps to avoid phishing attempts by contacting the company that is the subject of the email to check that the email is legitimate or by typing in a trusted web address for the company's website into the address bar of their browser to bypass the link in the suspected phishing message.
Nearly all legitimate email messages from companies to their customers will contain an item of information that is not readily available to phishers. Some companies, like PayPal, always address their customers by their username in emails, so if an email addresses a user in a generic fashion ("Dear PayPal customer") it is likely to be an attempt at phishing. Emails from banks and credit card companies will often include partial account numbers. Therefore, one should always be suspicious if the message does not contain specific personal information. Phishing attempts in early 2006, however, used such highly personalized information, making it unsafe to rely on personal information alone as a sign that a message is legitimate. Further, another recent study concluded in part that the presence of this information does not significantly affect the success rate of phishing attacks, suggesting that most users do not pay attention to such details anyway.
The Anti-Phishing Working Group, an industry and law enforcement association, has suggested that conventional phishing techniques could become obsolete in the future as people are increasingly aware of the social engineering techniques used by phishers. They propose that pharming and other uses of malware will become more common tools for stealing information.
Anti-phishing software is available that may identify phishing contents on websites, act as a toolbar that displays the real domain name for the visited website, or spot phishing attempts in email. Microsoft's new IE7 browser, Mozilla Firefox 2.0, and Opera from version 9.1 include a form of anti-phishing technology, by which a site may be checked against a list of known phishing sites. If the site is a suspect the software may either warn a user or block the site outright.  Firefox 2 uses Google anti-phishing software, which may also be installed under IE6. Spam filters also help, because they reduce the number of phishing emails that users receive.  An approach introduced in mid-2006 (similar in principle to using a hosts file to block web adverts) involves switching to using a special DNS service that filters out known phishing domains, which will work with any browser.
Security skins present a user-selected secret image whenever a password is requested; if the image does not appear, then the site is not legitimate. Bank of America use these together with challenge questions, which ask the user for information that should be known only to the user and the bank. This feature (and other forms of two-way authentication and two-factor authentication) is still susceptible to attacks, such as those suffered by Scandinavian bank Nordea in late 2005, and Citibank in 2006.
To mitigate the problem of phishing sites spoofing a victim site and directly using its real images, several site owners have responded by altering the images to send a message to the visitor. If the images were not requested in the normal way by visiting the real page then a warning that the site is fraudulent can be substituted for the usual image, or the original image can be moved to a new filename and the original permanently replaced with a warning.  
Monitoring and takedown
Several companies offer banks and other entities likely to suffer from phishing scams 24/7 services to monitor, analyze and assist in shutting down phishing websites. Individuals can contribute by reporting phishing to both volunteer and industry groups, such as PhishTank.
On January 26, 2004, the FTC (Federal Trade Commission) filed the first lawsuit against a suspected phisher. The defendant, a Californian teenager, allegedly created and used a webpage designed to look like the America Online website, so that he could steal credit card numbers. Other countries have followed the lead of the U.S. by tracing and arresting phishers. A phishing kingpin, Valdir Paulo de Almeida, was arrested in Brazil for leading one of the largest phishing crime rings, which in 2 years stole between $18 and $37 million USD. UK authorities jailed two men in June 2005 for their role in a phishing scam, in a case connected to the US Secret Service Operation Firewall, which targeted notorious "carder" websites. In 2006 eight people were arrested by Japanese police on suspicion of phishing fraud by creating bogus Yahoo Japan Web sites, netting themselves 100 million yen ($870 thousand USD). The arrests continued in 2006 with the FBI Operation Cardkeeper detaining a gang of sixteen in the U.S. and Europe.
In the United States, Democratic Senator Patrick Leahy introduced the Anti-Phishing Act of 2005 on March 1, 2005. The federal anti-phishing bill proposes that criminals who create fake web sites and spam bogus emails in order to defraud consumers could receive a fine up to $250,000 and receive jail terms of up to five years. The UK has strengthened the legal arsenal against phishing with the Fraud Act 2006, which introduces a general offence of fraud that can carry up to a ten year sentence, and prohibits writing or possessing phishing kits with intent to commit fraud. 
Companies have also joined the effort to crack down on phishing. On March 31, 2005, Microsoft filed 117 federal lawsuits in the U.S. District Court for the Western District of Washington. The lawsuits accuse "John Doe" defendants of using various methods to obtain passwords and confidential information. March 2005 also saw Microsoft partner with the Australian government to teach law enforcement officials how to combat various cyber crimes, including phishing.. Microsoft announced a planned further 100 lawsuits outside the U.S. in March 2006, followed by the commencement, as of November 2006, of 129 lawsuits mixing criminal and civil actions.
AOL reinforced its efforts against phishing in early 2006 with three lawsuits seeking a total of $18 million USD under the 2005 amendments to the Virginia Computer Crimes Act, and Earthlink has joined in by helping to identify six men subsequently charged with phishing fraud in Connecticut.
- Anti-phishing software
- Computer insecurity
- Defensive computing
- E-mail spoofing
- Rock Phish Kit
- Social engineering
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- Anti-Phishing Working Group - News about phishing and anti-phishing control methods.
- Bank Safe Online - Advice to UK consumers regarding phishing.
- Banking Scam Revealed - A public forensic examination of a phishing attack.
- CIMIP - Center for Identity Management and Information Protection.
- Duke Law & Technology Review - Plugging the "phishing" hole: legislation versus technology.
- FBI E-scams and Warnings Update - Summaries of new or active scams that use the web or e-mail.
- FTC Consumer Alert - How not to get hooked by a phishing scam.
- How Phishing Actually Works - How the bad guys actually operate.
- Indiana University Phishing Group - Collection of research articles on phishing.
- Know Your Enemy: Phishing - Case study from the Honeynet Project on detailed techniques of a couple of phishers.
- Phishing Detection and Prevention: Practical Counter-Fraud Solutions - Industry whitepaper exploring various counter-fraud techniques.
- The Phishing Guide: Understanding and Preventing Phishing Attacks - The technologies and security flaws phishers exploit.
- Phishing IQ Test - Find out how well you can recognize a Phishing email.
- Phishing mailing list - Phishing discussion, research and mitigation.
- Phishing scams gallery - A large and growing gallery of phishing examples.
- Spot phishing scams - Recognize Phishing Scams.