An example of a phishing email, disguised as an official email from a [fictional] bank. The sender is attempting to trick the recipient into revealing confidential information by "confirming" it at the phisher's website. Note the misspelling of the words received and discrepancy as recieved and discrepency, respectively.
Phishing is a type of social engineering where an attacker sends a fraudulent [e.g., spoofed, fake, or otherwise deceptive] message designed to trick a person into revealing sensitive information to the attacker[1] 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.[2] As of 2020, phishing is by far the most common attack performed by cybercriminals, the FBI's Internet Crime Complaint Centre recording over twice as many incidents of phishing than any other type of computer crime.[3]
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 2600.[4][5][6] The word is a variant of fishing, influenced by phreaking, and alludes to the use of increasingly sophisticated lures to "fish" for users' sensitive information.[5][7][8]
Attempts to prevent or mitigate the impact of phishing incidents include legislation, user training, public awareness, and technical security measures.[9] Phishing awareness has become important at home and at the work place. For instance, from 2017 to 2020, phishing attacks have increased from 72% to 86% among businesses.[10]
Types[edit]
Email phishing[edit]
Most phishing messages are delivered by email spam, and are not personalized or targeted to a specific individual or company–this is termed "bulk" phishing.[11] 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.[12] 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.[5] Compromised streaming service accounts are usually sold directly to consumers on darknet markets.[13]
Spear phishing[edit]
Spear phishing involves an attacker directly targeting a specific organization or person with tailored phishing communications.[14] This is essentially the creation and sending of emails to a particular person to make the person think the email is legitimate. 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.[15][16][17][18] 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.[19]
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.[20][21]
A recent study tested the susceptibility of certain age groups against spear phishing. In total, 100 young and 58 older users received, without their knowledge, daily simulated phishing emails over 21 days. A browser plugin recorded their clicking on links in the emails as an indicator of their susceptibility. Forty-three percent of users fell for the simulated phishing emails, with older women showing the highest susceptibility. While susceptibility in young users declined across the study, susceptibility in older users remained stable.[22]
Whaling and CEO fraud[edit]
Whaling refers to spear phishing attacks directed specifically at senior executives and other high-profile targets.[23] The content will be likely crafted to be of interest to the person or role targeted - such as a subpoena or customer complaint.[24]
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.[25] 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.[26]
Clone phishing[edit]
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.[27][28]
Voice phishing[edit]
Voice phishing, or vishing,[29] 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.[29] 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.[30]
SMS phishing[edit]
SMS phishing[31] or smishing[32][33] is conceptually similar to email phishing, except attackers use cell phone text messages to deliver the "bait".[34] 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.[35] 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.[36]
Page hijacking[edit]
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.[citation needed]
Calendar phishing[edit]
Calendar phishing is when phishing links are delivered via calendar invitations. Calendar invitations are sent, which by default, are automatically added to many calendars. These invitations often take the form of RSVP and other common event requests.[37] Former Google click fraud czar Shuman Ghosemajumder believes this form of fraud is increasing, and recommends changing calendar settings to not automatically add new invitations.[38]
Techniques[edit]
Link manipulation[edit]
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.[39] Misspelled URLs or the use of subdomains are common tricks used by phishers. In the following example URL, //www.yourbank.example.com/, it can appear to the untrained eye as
though the URL will take the user 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.[40] Equivalent mobile apps generally do not have this preview
feature.[citation needed]
Internationalized domain names [IDNs] can be exploited via IDN spoofing[41] or homograph attacks,[42] 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.[43][44][45] 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.[46]
Filter evasion[edit]
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.[47] In response, more sophisticated anti-phishing filters are able to recover hidden text in images using optical character recognition [OCR].[48]
[edit]
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.[49] This occurs most often with victims bank or insurance accounts.[50]
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. These links are designed to take you to a professional looking website that looks exactly like the legitimate organization's website.[51] 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.[52]
History[edit]
1980s[edit]
A phishing technique was described in detail in a paper and presentation delivered to the 1987 International HP Users Group, Interex.[53]
1990s[edit]
The term "phishing" is said to have been coined by the well known spammer and hacker in the mid-90s, Khan C. Smith.[54] 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.[55][56]
Early AOL phishing[edit]
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 "