Phishing

Phishing is a type of social engineering where an attacker sends a fraudulent ("spoofed") message designed to trick a human victim into revealing sensitive information to the attacker or to deploy malicious software on the victim's infrastructure like ransomware. Phishing attacks have become increasingly sophisticated and often transparently mirror the site being targeted, allowing the attacker to observe everything while the victim is navigating the site, and transverse any additional security boundaries with the victim. As of 2020, phishing is by far the most common attack performed by cyber-criminals, with the FBI's Internet Crime Complaint Centre recording over twice as many incidents of phishing than any other type of computer crime.
The first recorded use of the term "phishing" was in the cracking toolkit AOHell created by Koceilah Rekouche in 1995, however it is possible that the term was used before this in a print edition of the hacker magazine "". The word is a leetspeak variant of "fishing" ("ph" is a common replacement for "f" ), probably influenced by phreaking, and alludes to the use of increasingly sophisticated lures to "fish" for users' sensitive information.
Attempts to prevent or mitigate the impact of phishing incidents include legislation, user training, public awareness, and technical security measures.
Types.
Email phishing.
Most phishing messages are delivered by email, and are not personalized or targeted to a specific individual or company–this is termed "bulk" phishing. The content of a bulk phishing message varies widely depending on the goal of the attacker–common targets for impersonation include banks and financial services, email and cloud productivity providers, and streaming services. Attackers may use the credentials obtained to directly steal money from a victim, although compromised accounts are often used instead as a jumping-off point to perform other attacks, such as the theft of proprietary information, the installation of malware, or the spear phishing of other people within the target's organization. Compromised streaming service accounts are usually sold directly to consumers on darknet markets.
Spear phishing.
Spear phishing involves an attacker directly targeting a specific organization or person with tailored phishing emails. In contrast to bulk phishing, spear phishing attackers often gather and use personal information about their target to increase their probability of success of the attack. Spear phishing typically targets executives or those that work in financial departments that have access to the organization's sensitive financial data and services. A 2019 study showed that accountancy and audit firms are frequent targets for spear phishing owing to their employees' access to information that could be valuable to criminals. 
Threat Group-4127 (Fancy Bear) used spear phishing tactics to target email accounts linked to Hillary Clinton's 2016 presidential campaign. They attacked more than 1,800 Google accounts and implemented the accounts-google.com domain to threaten targeted users.
Whaling and CEO fraud.
Whaling refers to spear phishing attacks directed specifically at senior executives and other high-profile targets. The content will be likely crafted to be of interest to the person or role targeted - such as a subpoena or customer complaint.
CEO fraud is effectively the opposite of whaling; it involves the crafting of spoofed emails purportedly "from" senior executives with the intention of getting other employees at an organization to perform a specific action, usually the wiring of money to an offshore account. While CEO fraud has a reasonably low success rate, criminals can gain very large sums of money from the few attempts that do succeed. There have been multiple instances of organizations losing tens of millions of dollars to such attacks.
Clone phishing.
Clone phishing is a type of phishing attack whereby a legitimate, and previously delivered email containing an attachment or link has had its content and recipient address(es) taken and used to create an almost identical or cloned email. The attachment or link within the email is replaced with a malicious version and then sent from an email address spoofed to appear to come from the original sender. It may claim to be a resend of the original or an updated version to the original. Typically this requires either the sender or recipient to have been previously hacked for the malicious third party to obtain the legitimate email.
Voice phishing.
Voice phishing, or vishing, is the use of telephony (often Voice over IP telephony) to conduct phishing attacks. Attackers will dial a large quantity of telephone numbers and play automated recordings - often made using text to speech synthesizers - that make false claims of fraudulent activity on the victim's bank accounts or credit cards. The calling phone number will be spoofed to show the real number of the bank or institution impersonated. The victim is then directed to call a number controlled by the attackers, which will either automatically prompt them to enter sensitive information in order to "resolve" the supposed fraud, or connect them to a live person who will attempt to use social engineering to obtain information. Voice phishing capitalizes on the lower awareness among the general public of techniques such as caller ID spoofing and automated dialing, compared to the equivalents for email phishing, and thereby the inherent trust that many people have in voice telephony.
SMS phishing.
SMS phishing or smishing is conceptually similar to email phishing, except attackers use cell phone text messages to deliver the 'bait'. Smishing attacks typically invite the user to click a link, call a phone number, or contact an email address provided by the attacker via SMS message. The victim is then invited to provide their private data; often, credentials to other websites or services. Furthermore, due to the nature of mobile browsers, URLs may not be fully displayed; this may make it more difficult to identify an illegitimate logon page. As the mobile phone market is now saturated with smartphones which all have fast internet connectivity, a malicious link sent via SMS can yield the same result as it would if sent via email. Smishing messages may come from telephone numbers that are in a strange or unexpected format.
Page hijacking.
Page hijacking involves compromising legitimate web pages in order to redirect users to a malicious website or an exploit kit via cross site scripting. A hacker may compromise a website and insert an exploit kit such as MPack in order to compromise legitimate users who visit the now compromised web server. One of the simplest forms of page hijacking involves altering a webpage to contain a malicious inline frame which can allow an exploit kit to load. Page hijacking is frequently used in tandem with a watering hole attack on corporate entities in order to compromise targets.
Techniques.
Link manipulation.
Most types of phishing use some form of technical deception designed to make a link in an email appear to belong to the organization the attackers are impersonating. Misspelled URLs or the use of subdomains are common tricks used by phishers. In the following example URL, , it can appear to the untrained eye as though the URL will take you to the "example" section of the "yourbank" website; actually this URL points to the "yourbank" (i.e. phishing) section of the "example" website. Another common trick is to make the displayed text for a link suggest a reliable destination, when the link actually goes to the phishers' site. Many desktop email clients and web browsers will show a link's target URL in the status bar while hovering the mouse over it. This behavior, however, may in some circumstances be overridden by the phisher. Equivalent mobile apps generally do not have this preview feature.
Internationalized domain names (IDNs) can be exploited via IDN spoofing or homograph attacks, to create web addresses visually identical to a legitimate site, that lead instead to malicious version. 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. Even digital certificates do not solve this problem because it is quite possible for a phisher to purchase a valid certificate and subsequently change content to spoof a genuine website, or, to host the phish site without SSL at all.
Filter evasion.
Phishers have sometimes used images instead of text to make it harder for anti-phishing filters to detect the text commonly used in phishing emails. In response, more sophisticated anti-phishing filters are able to recover hidden text in images using optical character recognition (OCR).
Social engineering.
Most types of phishing involve some kind of social engineering, in which users are psychologically manipulated into performing an action such as clicking a link, opening an attachment, or divulging confidential information. In addition to the obvious impersonation of a trusted entity, most phishing involves the creation of a sense of urgency - attackers claim that accounts will be shut down or seized unless the victim takes an action.
An alternative technique to impersonation-based phishing is the use of fake news articles designed to provoke outrage, causing the victim to click a link without properly considering where it could lead. Once on the attacker's website, victims can be presented with imitation "virus" notifications or redirected to pages that attempt to exploit web browser vulnerabilities to install malware.
History.
1980s.
A phishing technique was described in detail in a paper and presentation delivered to the 1987 International HP Users Group, Interex.
1990s.
The term "phishing" is said to have been coined by the well known spammer and hacker in the mid-90s, Khan C. Smith. The first recorded mention of the term is found in the hacking tool AOHell (according to its creator), which included a function for attempting to steal the passwords or financial details of America Online users.
Early AOL phishing.
Phishing on AOL was closely associated with the warez community that exchanged unlicensed software and the black hat hacking scene that perpetrated credit card fraud and other online crimes. AOL enforcement would detect words used in AOL chat rooms to suspend the accounts of individuals involved in counterfeiting software and trading stolen accounts. The term was used because "<><" is the single most common tag of HTML that was found in all chat transcripts naturally, and as such could not be detected or filtered by AOL staff. The symbol <>< was replaced for any wording that referred to stolen credit cards, accounts, or illegal activity. Since the symbol looked like a fish, and due to the popularity of phreaking it was adapted as "Phishing". AOHell, released in early 1995, was a program designed to hack AOL users by allowing the attacker to 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 imperatives such as "verify your account" or "confirm billing information".
Once the victim had revealed the password, the attacker could access and use the victim's account for fraudulent purposes. 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". A user using both an AIM account and an AOL account from an ISP simultaneously could phish AOL members with relative impunity as internet AIM accounts could be used by non-AOL internet members and could not be actioned (i.e., reported to AOL TOS department for disciplinary action).. In late 1995, AOL crackers resorted to phishing for legitimate accounts after AOL brought in measures in late 1995 to prevent using fake, algorithmically generated credit card numbers to open accounts. Eventually, AOL's policy enforcement forced copyright infringement off AOL servers, and AOL 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.
Anti-phishing.
There are anti-phishing websites which publish exact messages that have been recently circulating the internet, such as FraudWatch International and Millersmiles. Such sites often provide specific details about the particular messages.
As recently as 2007, the adoption of anti-phishing strategies by businesses needing to protect personal and financial information was low. Now there are several different techniques to combat phishing, including legislation and technology created specifically to protect against phishing. These techniques include steps that can be taken by individuals, as well as by organizations. Phone, web site, and email phishing can now be reported to authorities, as described below.
User training.
People can be trained to recognize phishing attempts, and to deal with them through a variety of approaches. Such education can be effective, especially where training emphasizes conceptual knowledge and provides direct feedback.
Many organizations run regular simulated phishing campaigns targeting their staff to measure the effectiveness of their training.
People can take steps to avoid phishing attempts by slightly modifying their browsing habits. When contacted about an account needing to be "verified" (or any other topic used by phishers), it is a sensible precaution to contact the company from which the email apparently originates to check that the email is legitimate. Alternatively, the address that the individual knows is the company's genuine website can be typed into the address bar of the browser, rather than trusting any hyperlinks in the suspected phishing message.
Nearly all legitimate e-mail messages from companies to their customers contain an item of information that is not readily available to phishers. Some companies, for example PayPal, always address their customers by their username in emails, so if an email addresses the recipient in a generic fashion ("Dear PayPal customer") it is likely to be an attempt at phishing. Furthermore, PayPal offers various methods to determine spoof emails and advises users to forward suspicious emails to their spoof@PayPal.com domain to investigate and warn other customers. However it is unsafe to assume that the presence of personal information alone guarantees that a message is legitimate, and some studies have shown that the presence of personal information does not significantly affect the success rate of phishing attacks; which suggests that most people do not pay attention to such details.
Emails from banks and credit card companies often include partial account numbers. However, recent research has shown that the public do not typically distinguish between the first few digits and the last few digits of an account number—a significant problem since the first few digits are often the same for all clients of a financial institution.
The Anti-Phishing Working Group produces regular report on trends in phishing attacks.
Google posted a video demonstrating how to identify and protect yourself from Phishing scams.
Technical approaches.
A wide range of technical approaches are available to prevent phishing attacks reaching users or to prevent them from successfully capturing sensitive information.
Filtering out phishing mail.
Specialized spam filters can reduce the number of phishing emails that reach their addressees' inboxes. These filters use a number of techniques including machine learning and natural language processing approaches to classify phishing emails, and reject email with forged addresses.
Browsers alerting users to fraudulent websites.
Another popular approach to fighting phishing is to maintain a list of known phishing sites and to check websites against the list. One such service is the Safe Browsing service. Web browsers such as Google Chrome, Internet Explorer 7, Mozilla Firefox 2.0, Safari 3.2, and Opera all contain this type of anti-phishing measure. Firefox 2 used Google anti-phishing software. Opera 9.1 uses live blacklists from Phishtank, cyscon and GeoTrust, as well as live whitelists from GeoTrust. Some implementations of this approach send the visited URLs to a central service to be checked, which has raised concerns about privacy. According to a report by Mozilla in late 2006, Firefox 2 was found to be more effective than Internet Explorer 7 at detecting fraudulent sites in a study by an independent software testing company.
An approach introduced in mid-2006 involves switching to a special DNS service that filters out known phishing domains: this will work with any browser, and is similar in principle to using a hosts file to block web adverts.
To mitigate the problem of phishing sites impersonating a victim site by embedding its images (such as logos), several site owners have altered the images to send a message to the visitor that a site may be fraudulent. The image may be moved to a new filename and the original permanently replaced, or a server can detect that the image was not requested as part of normal browsing, and instead send a warning image.
Augmenting password logins.
The Bank of America website is one of several that asks users to select a personal image (marketed as SiteKey) and displays this user-selected image with any forms that request a password. Users of the bank's online services are instructed to enter a password only when they see the image they selected. However, several studies suggest that few users refrain from entering their passwords when images are absent. In addition, this feature (like other forms of two-factor authentication) is susceptible to other attacks, such as those suffered by Scandinavian bank Nordea in late 2005, and Citibank in 2006.
A similar system, in which an automatically generated "Identity Cue" consisting of a colored word within a colored box is displayed to each website user, is in use at other financial institutions.
Security skins are a related technique that involves overlaying a user-selected image onto the login form as a visual cue that the form is legitimate. Unlike the website-based image schemes, however, the image itself is shared only between the user and the browser, and not between the user and the website. The scheme also relies on a mutual authentication protocol, which makes it less vulnerable to attacks that affect user-only authentication schemes.
Still another technique relies on a dynamic grid of images that is different for each login attempt. The user must identify the pictures that fit their pre-chosen categories (such as dogs, cars and flowers). Only after they have correctly identified the pictures that fit their categories are they allowed to enter their alphanumeric password to complete the login. Unlike the static images used on the Bank of America website, a dynamic image-based authentication method creates a one-time passcode for the login, requires active participation from the user, and is very difficult for a phishing website to correctly replicate because it would need to display a different grid of randomly generated images that includes the user's secret categories.
Monitoring and takedown.
Several companies offer banks and other organizations likely to suffer from phishing scams round-the-clock services to monitor, analyze and assist in shutting down phishing websites. Automated detection of phishing content is still below accepted levels for direct action, with content-based analysis reaching between 80 and 90% of success so most of the tools include manual steps to certify the detection and authorize the response. Individuals can contribute by reporting phishing to both volunteer and industry groups, such as cyscon or PhishTank. Phishing web pages and emails can be reported to Google.
Transaction verification and signing.
Solutions have also emerged using the mobile phone (smartphone) as a second channel for verification and authorization of banking transactions.
Multi-factor authentication.
Organizations can implement two factor or multi-factor authentication (MFA), which requires a user to use at least 2 factors when logging in. (For example, a user must both present a smart card and a password). This mitigates some risk, in the event of a successful phishing attack, the stolen password on its own cannot be reused to further breach the protected system. However, there are several attack methods which can defeat many of the typical systems. MFA schemes such as WebAuthn address this issue by design.
Email content redaction.
Organizations that prioritize security over convenience can require users of its computers to use an email client that redacts URLs from email messages, thus making it impossible for the reader of the email to click on a link, or even copy a URL. While this may result in an inconvenience, it does almost completely eliminate email phishing attacks.
Limitations of technical responses.
An article in "Forbes" in August 2014 argues that the reason phishing problems persist even after a decade of anti-phishing technologies being sold is that phishing is "a technological medium to exploit human weaknesses" and that technology cannot fully compensate for human weaknesses.
Legal responses.
On January 26, 2004, the U.S. Federal Trade Commission filed the first lawsuit against a suspected phisher. The defendant, a Californian teenager, allegedly created a webpage designed to look like the America Online website, and used it to steal credit card information. Other countries have followed this lead 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 two years stole between and . UK authorities jailed two men in June 2005 for their role in a phishing scam, in a case connected to the U.S. 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 (). 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, Senator Patrick Leahy introduced the "Anti-Phishing Act of 2005" in Congress on March 1, 2005. This bill, if it had been enacted into law, would have subjected criminals who created fake web sites and sent bogus emails in order to defraud consumers to fines of up to and prison terms of up to five years.
The UK strengthened its legal arsenal against phishing with the Fraud Act 2006, which introduces a general offence of fraud that can carry up to a ten-year prison sentence, and prohibits the development or possession of 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 obtaining passwords and confidential information. March 2005 also saw a partnership between Microsoft and the Australian government teaching 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 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.
In January 2007, Jeffrey Brett Goodin of California became the first defendant convicted by a jury under the provisions of the CAN-SPAM Act of 2003. He was found guilty of sending thousands of emails to America Online users, while posing as AOL's billing department, which prompted customers to submit personal and credit card information. Facing a possible 101 years in prison for the CAN-SPAM violation and ten other counts including wire fraud, the unauthorized use of credit cards, and the misuse of AOL's trademark, he was sentenced to serve 70 months. Goodin had been in custody since failing to appear for an earlier court hearing and began serving his prison term immediately.