Ransomware

Ransomware attacks are typically carried out using a Trojan disguised as a legitimate file that the user is tricked into downloading or opening when it arrives as an email attachment.

Ransomware attacks are typically carried out using a Trojan, entering a system through, for example, a malicious attachment, an embedded link in a phishing email, or a vulnerability in a network service.

Payloads may display a fake warning purportedly by an entity such as a law enforcement agency, falsely claiming that the system has been used for illegal activities, contains content such as pornography and "pirated" media.

[1][22][23] Payment is virtually always the goal, and the victim is coerced into paying for the ransomware to be removed either by supplying a program that can decrypt the files, or by sending an unlock code that undoes the payload's changes.

A range of such payment methods have been used, including wire transfers, premium-rate text messages,[24] pre-paid voucher services such as paysafecard,[7][25][26] and the Bitcoin cryptocurrency.

Its payload hid the files on the hard drive and encrypted only their names, and displayed a message claiming that the user's license to use a certain piece of software had expired.

[31] The idea of abusing anonymous cash systems to safely collect ransom from human kidnapping was introduced in 1992 by Sebastiaan von Solms and David Naccache.

[50] Some ransomware strains have used proxies tied to Tor hidden services to connect to their command and control servers, increasing the difficulty of tracing the exact location of the criminals.

started to offer the technology as a service, wherein ransomware is sold, ready for deployment on victims' machines, on a subscription basis, similarly to Adobe Creative Cloud or Office 365.

Instead, WinLock trivially restricted access to the system by displaying pornographic images and asked users to send a premium-rate SMS (costing around US$10) to receive a code that could be used to unlock their machines.

[17] In 2012, Symantec reported spread out of Eastern Europe of ransomware with a lock screen purporting to be law enforcement demanding payment for illegal activity.

Unlike its Windows-based counterparts, it does not block the entire computer, but simply exploits the behaviour of the web browser itself to frustrate attempts to close the page through normal means.

[59] In July 2013, a 21-year-old man from Virginia, whose computer coincidentally did contain pornographic photographs of underage girls with whom he had conducted sexualized communications, turned himself in to police after receiving and being deceived by FBI MoneyPak Ransomware accusing him of possessing child pornography.

Rather than random emails, the gangs stole credentials, found vulnerabilities in target networks, and improved the malware to avoid detection by anti-malware scanners.

[57] The big problem is that millions of dollars are lost by some organizations and industries that have decided to pay, such as the Hollywood Presbyterian Medical Center and the MedStar Health.

In late 2019 ransomware group Maze downloaded companies' sensitive files before locking them, and threatened to leak the data publicly if the ransom was not paid; in at least one case they did this.

This decreased to $813m in 2024, with a sharp drop in the second half of the year, according to research firm Chainalysis, attributed to victims refusing to pay, and action by law enforcement.

[7][18] In May 2012, Trend Micro threat researchers discovered templates for variations for the United States and Canada, suggesting that its authors may have been planning to target users in North America.

The Trojans spread via fraudulent e-mails claiming to be failed parcel delivery notices from Australia Post; to evade detection by automatic e-mail scanners that follow all links on a page to scan for malware, this variant was designed to require users to visit a web page and enter a CAPTCHA code before the payload is actually downloaded, preventing such automated processes from being able to scan the payload.

[96][97][98] Another Trojan in this wave, TorrentLocker, initially contained a design flaw comparable to CryptoDefense; it used the same keystream for every infected computer, making the encryption trivial to overcome.

Due to another design change, it is also unable to actually unlock a system after the ransom is paid; this led to security analysts speculating that the attack was not meant to generate illicit profit, but to simply cause disruption.

[118] As it used corporate network structures to spread, the ransomware was also discovered in other countries, including Turkey, Germany, Poland, Japan, South Korea, and the United States.

The virus has been behind attacks on government and healthcare targets, with notable hacks occurring against the town of Farmington, New Mexico, the Colorado Department of Transportation, Davidson County, North Carolina, and most recently,[when?]

Following the attack, DarkSide posted a statement claiming that "We are apolitical, we do not participate in geopolitics...Our goal is to make money and not creating problems for society."

[129][130] Ransomware-as-a-service (RaaS) became a notable method after the Russia-based[131] or Russian-speaking[132] group REvil staged operations against several targets, including the Brazil-based JBS S.A. in May 2021, and the US-based Kaseya Limited in July 2021.

Using software or other security policies to block known payloads from launching will help to prevent infection, but will not protect against all attacks[27][139] As such, having a proper backup solution is a critical component to defending against ransomware.

and ways of collective participation[150] In August 2021, the Cybersecurity and Infrastructure Security Agency (CISA) released a report that provided guidance for how to mitigate ransomware attacks.

A 2019 ProPublica investigation found the cybersecurity firms Proven Data Recovery and Monstercloud, which advertised ransom-free decryption services, would typically simply pay the ransom and charge the victim a higher price.

Each of the adverts that were promoted on the websites contained the Reveton Ransomware strain of the malicious Angler Exploit Kit (AEK)[162] that seized control of the machine.

[163] A breakthrough, in this case, occurred in May 2013 when authorities from several countries seized the Liberty Reserve servers, obtaining access to all its transactions and account history.