From Wikipedia, the free encyclopedia
Ransomware is a type of malware from cryptovirology that threatens to publish the victim’s data or perpetually block access to it unless a ransom
is paid. While some simple ransomware may lock the system in a way
which is not difficult for a knowledgeable person to reverse, more
advanced malware uses a technique called cryptoviral extortion, in which
it encrypts the victim’s files, making them inaccessible, and demands a ransom payment to decrypt them. In a properly implemented cryptoviral extortion attack, recovering the files without the decryption key is an intractable problem – and difficult to trace digital currencies such as Ukash or Bitcoin and other cryptocurrency are used for the ransoms, making tracing and prosecuting the perpetrators difficult.
Ransomware attacks are typically carried out using a Trojan
that is disguised as a legitimate file that the user is tricked into
downloading or opening when it arrives as an email attachment. However,
one high-profile example, the “WannaCry worm“, travelled automatically between computers without user interaction.
Starting from around 2012 the use of ransomware scams has grown internationally.
There were 181.5 million ransomware attacks in the first six months of
2018. This marks a 229% increase over this same time frame in 2017. In June 2014, vendor McAfee
released data showing that it had collected more than double the number
of samples of ransomware that quarter than it had in the same quarter
of the previous year. CryptoLocker was particularly successful, procuring an estimated US$3 million before it was taken down by authorities, and CryptoWall was estimated by the US Federal Bureau of Investigation (FBI) to have accrued over US$18 million by June 2015.
- 1 Operation
- 2 History
- 3 Notable examples
- 4 Mitigation
- 5 The growing threat of malware
- 6 Freedom of speech challenges and criminal punishment
- 7 Ransomware arrests and convictions
- 8 See also
- 9 References
- 10 Further reading
- 11 External links
The concept of file-encrypting ransomware was invented and implemented by Young and Yung at Columbia University and was presented at the 1996 IEEE Security & Privacy conference. It is called cryptoviral extortion and it was inspired by the fictional facehugger in the movie Alien. Cryptoviral extortion is the following three-round protocol carried out between the attacker and the victim.
- [attacker→victim] The attacker generates a key pair and places the corresponding public key in the malware. The malware is released.
- [victim→attacker] To carry out the cryptoviral extortion
attack, the malware generates a random symmetric key and encrypts the
victim’s data with it. It uses the public key in the malware to encrypt
the symmetric key. This is known as hybrid encryption
and it results in a small asymmetric ciphertext as well as the
symmetric ciphertext of the victim’s data. It zeroizes the symmetric key
and the original plaintext data to prevent recovery. It puts up a
message to the user that includes the asymmetric ciphertext and how to
pay the ransom. The victim sends the asymmetric ciphertext and e-money
to the attacker.
- [attacker→victim] The attacker receives the payment,
deciphers the asymmetric ciphertext with the attacker’s private key, and
sends the symmetric key to the victim. The victim deciphers the
encrypted data with the needed symmetric key thereby completing the
The symmetric key
is randomly generated and will not assist other victims. At no point is
the attacker’s private key exposed to victims and the victim need only
send a very small ciphertext (the encrypted symmetric-cipher key) to the
Ransomware attacks are typically carried out using a Trojan, entering a system through, for example, a malicious attachment, embedded link in a Phishing email, or a vulnerability in a network service. The program then runs a payload, which locks the system in some fashion, or claims to lock the system but does not (e.g., a scareware program). 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.
Some payloads consist simply of an application designed to lock
or restrict the system until payment is made, typically by setting the Windows Shell to itself, or even modifying the master boot record and/or partition table to prevent the operating to the system from booting until it is repaired. The most sophisticated payloads encrypt files, with many using strong encryption to encrypt the victim’s files in such a way that only the malware author has the needed decryption key.
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. While the attacker may simply take the
money without returning the victim’s files, it is in the attacker’s best
interest to perform the decryption as agreed, since victims will stop
sending payments if it becomes known that they serve no purpose. A key
element in making ransomware work for the attacker is a convenient
payment system that is hard to trace. A range of such payment methods
have been used, including wire transfers, premium-rate text messages, pre-paid voucher services such as paysafecard, and the digital currency bitcoin.
The first known malware extortion attack, the “AIDS Trojan” written by Joseph Popp
in 1989, had a design failure so severe it was not necessary to pay the
extortionist at all. 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. The user was asked to pay US$189
to “PC Cyborg Corporation” in order to obtain a repair tool even though
the decryption key could be extracted from the code of the Trojan. The
Trojan was also known as “PC Cyborg”. Popp was declared mentally unfit to stand trial for his actions, but he promised to donate the profits from the malware to fund AIDS research.
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. This electronic money collection method was also proposed for cryptoviral extortion attacks.
In the von Solms-Naccache scenario a newspaper publication was used
(since bitcoin ledgers did not exist at the time the paper was written).
The notion of using public key cryptography for data kidnapping attacks was introduced in 1996 by Adam L. Young and Moti Yung. Young and Yung critiqued the failed AIDS Information Trojan that relied on symmetric cryptography
alone, the fatal flaw being that the decryption key could be extracted
from the Trojan, and implemented an experimental proof-of-concept
cryptovirus on a Macintosh SE/30 that used RSA and the Tiny Encryption Algorithm (TEA) to hybrid encrypt the victim’s data. Since public key crypto is used, the cryptovirus only contains the encryption key. The attacker keeps the corresponding private
decryption key private. Young and Yung’s original experimental
cryptovirus had the victim send the asymmetric ciphertext to the
attacker who deciphers it and returns the symmetric decryption key it
contains to the victim for a fee. Long before electronic money
existed Young and Yung proposed that electronic money could be extorted
through encryption as well, stating that “the virus writer can
effectively hold all of the money ransom until half of it is given to
him. Even if the e-money was previously encrypted by the user, it is of
no use to the user if it gets encrypted by a cryptovirus”. They referred to these attacks as being “cryptoviral extortion”, an overt attack that is part of a larger class of attacks in a field called cryptovirology, which encompasses both overt and covert attacks.
The cryptoviral extortion protocol was inspired by the parasitic
relationship between H. R. Giger’s facehugger and its host in the movie Alien.
Examples of extortionate ransomware became prominent in May 2005. By mid-2006, Trojans such as Gpcode, TROJ.RANSOM.A, Archiveus,
Krotten, Cryzip, and MayArchive began utilizing more sophisticated RSA
encryption schemes, with ever-increasing key-sizes. Gpcode.AG, which was
detected in June 2006, was encrypted with a 660-bit RSA public key.
In June 2008, a variant known as Gpcode.AK was detected. Using a
1024-bit RSA key, it was believed large enough to be computationally
infeasible to break without a concerted distributed effort.
Encrypting ransomware returned to prominence in late 2013 with the propagation of CryptoLocker—using the Bitcoin digital currency platform to collect ransom money. In December 2013, ZDNet
estimated based on Bitcoin transaction information that between 15
October and 18 December, the operators of CryptoLocker had procured
about US$27 million from infected users. The CryptoLocker technique was widely copied
in the months following, including CryptoLocker 2.0 (thought not to be
related to CryptoLocker), CryptoDefense (which initially contained a
major design flaw that stored the private key on the infected system in a
user-retrievable location, due to its use of Windows’ built-in encryption APIs), and the August 2014 discovery of a Trojan specifically targeting network-attached storage devices produced by Synology.
In January 2015, it was reported that ransomware-styled attacks have
occurred against individual websites via hacking, and through ransomware
designed to target Linux-based web servers.
The Microsoft Malware Protection Center identified a trend away from WSF files in favour of LNK files and PowerShell scripting.
These LNK shortcut files install Locky ransomware by automating
infection operations rather than relying on traditional user downloads
of WSF files—all of which is made possible by the universal PowerShell Windows application.
Unfortunately, cybercriminals have been able to leverage PowerShell for
their attacks for years. In a recent report, the application was found
to be involved in nearly 40% of endpoint security incidents.
While attackers have been finding weaknesses in the Windows operating
system for years, it’s clear that there’s something problematic with
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. Furthermore, dark web vendors have increasingly started to offer the technology as a service.
Symantec has classified ransomware to be the most dangerous cyber threat.
August 2010, Russian authorities arrested nine individuals connected to
a ransomware Trojan known as WinLock. Unlike the previous Gpcode
Trojan, WinLock did not use encryption. 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. The scam hit numerous users across Russia and
neighbouring countries—reportedly earning the group over US$16 million.
In 2011, a ransomware Trojan surfaced that imitated the Windows Product Activation
notice, and informed users that a system’s Windows installation had to
be re-activated due to “[being a] victim of fraud”. An online
activation option was offered (like the actual Windows activation
process), but was unavailable, requiring the user to call one of six international numbers
to input a 6-digit code. While the malware claimed that this call would
be free, it was routed through a rogue operator in a country with high
international phone rates, who placed the call on hold, causing the user
to incur large international long distance charges.
In February 2013, a ransomware Trojan based on the Stamp.EK exploit kit surfaced; the malware was distributed via sites hosted on the project hosting services SourceForge and GitHub that claimed to offer “fake nude pics” of celebrities. In July 2013, an OS X-specific
ransomware Trojan surfaced, which displays a web page that accuses the
user of downloading pornography. 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.
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. An investigation
discovered the incriminating files, and the man was charged with child sexual abuse and possession of child pornography.
Leakware (also called Doxware)
The converse of ransomware is a cryptovirology
attack invented by Adam L. Young that threatens to publish stolen
information from the victim’s computer system rather than deny the
victim access to it.
In a leakware attack, malware exfiltrates sensitive host data either to
the attacker or alternatively, to remote instances of the malware, and
the attacker threatens to publish the victim’s data unless a ransom is
paid. The attack was presented at West Point in 2003 and was summarized in the book Malicious Cryptography
as follows, “The attack differs from the extortion attack in the
following way. In the extortion attack, the victim is denied access to
its own valuable information and has to pay to get it back, where in the
attack that is presented here the victim retains access to the
information but its disclosure is at the discretion of the computer
The attack is rooted in game theory and was originally dubbed “non-zero
sum games and survivable malware”. The attack can yield monetary gain
in cases where the malware acquires access to information that may
damage the victim user or organization, e.g., the reputational damage
that could result from publishing proof that the attack itself was a
With the increased popularity of ransomware on PC platforms, ransomware targeting mobile operating systems
has also proliferated. Typically, mobile ransomware payloads are
blockers, as there is little incentive to encrypt data since it can be
easily restored via online synchronization. Mobile ransomware typically targets the Android platform, as it allows applications to be installed from third-party sources. The payload is typically distributed as an APK file installed by an unsuspecting user; it may attempt to display a blocking message over top of all other applications, while another used a form of clickjacking to cause the user to give it “device administrator” privileges to achieve deeper access to the system.
It recently has been shown that ransomware may also target ARM
architectures like those that can be found in various Internet-of-Things
(IoT) devices, such as Industrial IoT edge devices.
In August 2019 researchers demonstrated it’s possible to infect DSLR cameras with ransomware. Digital cameras often use Picture Transfer Protocol
(PTP – standard protocol used to transfer files.) Researchers found
that it was possible to exploit vulnerabilities in the protocol to
infect target camera(s) with ransomware (or execute any arbitrary code).
This attack was presented at the Defcon security conference in Las Vegas as a proof of concept attack (not as actual armed malware).
A Reveton payload, fraudulently claiming that the user must pay a fine to the Metropolitan Police Service
In 2012, a major ransomware Trojan known as Reveton began to spread. Based on the Citadel Trojan (which itself, is based on the Zeus
Trojan), its payload displays a warning purportedly from a law
enforcement agency claiming that the computer has been used for illegal
activities, such as downloading unlicensed software or child pornography. Due to this behaviour, it is commonly referred to as the “Police Trojan”.
The warning informs the user that to unlock their system, they would
have to pay a fine using a voucher from an anonymous prepaid cash
service such as Ukash or paysafecard. To increase the illusion that the computer is being tracked by law enforcement, the screen also displays the computer’s IP address, while some versions display footage from a victim’s webcam to give the illusion that the user is being recorded.
Reveton initially began spreading in various European countries in early 2012.
Variants were localized with templates branded with the logos of
different law enforcement organizations based on the user’s country; for
example, variants used in the United Kingdom contained the branding of
organizations such as the Metropolitan Police Service and the Police National E-Crime Unit. Another version contained the logo of the royalty collection society PRS for Music, which specifically accused the user of illegally downloading music.
In a statement warning the public about the malware, the Metropolitan
Police clarified that they would never lock a computer in such a way as
part of an investigation.
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. By August 2012, a new variant of Reveton began to spread in the United States, claiming to require the payment of a $200 fine to the FBI using a MoneyPak card. In February 2013, a Russian citizen was arrested in Dubai by Spanish authorities for his connection to a crime ring that had been using Reveton; ten other individuals were arrested on money laundering charges. In August 2014, Avast Software reported that it had found new variants of Reveton that also distribute password-stealing malware as part of its payload.
Main article: CryptoLocker
Encrypting ransomware reappeared in September 2013 with a Trojan known as CryptoLocker,
which generated a 2048-bit RSA key pair and uploaded in turn to a
command-and-control server, and used to encrypt files using a whitelist of specific file extensions. The malware threatened to delete the private key if a payment of Bitcoin
or a pre-paid cash voucher was not made within 3 days of the infection.
Due to the extremely large key size it uses, analysts and those
affected by the Trojan considered CryptoLocker extremely difficult to
Even after the deadline passed, the private key could still be obtained
using an online tool, but the price would increase to 10 BTC—which cost
approximately US$2300 as of November 2013.
CryptoLocker was isolated by the seizure of the Gameover ZeuS botnet as part of Operation Tovar, as officially announced by the U.S. Department of Justice on 2 June 2014. The Department of Justice also publicly issued an indictment against the Russian hacker Evgeniy Bogachev for his alleged involvement in the botnet. It was estimated that at least US$3 million was extorted with the malware before the shutdown.
CryptoLocker.F and TorrentLocker
In September 2014, a wave of ransomware Trojans surfaced that first targeted users in Australia, under the names CryptoWall and CryptoLocker
(which is, as with CryptoLocker 2.0, unrelated to the original
CryptoLocker). 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. Symantec determined that these new variants, which it identified as CryptoLocker.F, were again, unrelated to the original CryptoLocker due to differences in their operation. A notable victim of the Trojans was the Australian Broadcasting Corporation; live programming on its television news channel ABC News 24 was disrupted for half an hour and shifted to Melbourne studios due to a CryptoWall infection on computers at its Sydney studio.
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. However, this flaw was later fixed.
By late-November 2014, it was estimated that over 9,000 users had been
infected by TorrentLocker in Australia alone, trailing only Turkey with
major ransomware Trojan targeting Windows, CryptoWall, first appeared
in 2014. One strain of CryptoWall was distributed as part of a malvertising campaign on the Zedo
ad network in late-September 2014 that targeted several major websites;
the ads redirected to rogue websites that used browser plugin exploits
to download the payload. A Barracuda Networks researcher also noted that the payload was signed with a digital signature in an effort to appear trustworthy to security software.
to communicate with its servers. When encrypting files, the malware
also deletes volume shadow copies and installs spyware that steals
passwords and Bitcoin wallets.
The FBI reported in June 2015 that nearly 1,000 victims had contacted the bureau’s Internet Crime Complaint Center to report CryptoWall infections, and estimated losses of at least $18 million.
The most recent version, CryptoWall 4.0, enhanced its code to
avoid antivirus detection, and encrypts not only the data in files but
also the file names.
one of the major mobile ransomware families. Between April 2015 and
March 2016, about 56 percent of accounted mobile ransomware was Fusob.
Like a typical mobile ransomware, it employs scare tactics to extort people to pay a ransom. The program pretends to be an accusatory authority, demanding the victim to pay a fine from $100 to $200 USD
or otherwise face a fictitious charge. Rather surprisingly, Fusob
suggests using iTunes gift cards for payment. Also, a timer clicking
down on the screen adds to the users’ anxiety as well.
In order to infect devices, Fusob masquerades as a pornographic video player. Thus, victims, thinking it is harmless, unwittingly download Fusob.
When Fusob is installed, it first checks the language used in the
device. If it uses Russian or certain Eastern European languages, Fusob
does nothing. Otherwise, it proceeds on to lock the device and demand
ransom. Among victims, about 40% of them are in Germany with the United
Kingdom and the United States following with 14.5% and 11.4%
Fusob has lots in common with Small, which is another major
family of mobile ransomware. They represented over 93% of mobile
ransomware between 2015 and 2016.
Main article: WannaCry ransomware attack
In May 2017, the WannaCry ransomware attack spread through the Internet, using an exploit vector named EternalBlue, which was allegedly leaked from the U.S. National Security Agency. The ransomware attack, unprecedented in scale, infected more than 230,000 computers in over 150 countries, using 20 different languages to demand money from users using Bitcoin cryptocurrency. WannaCry demanded US$300 per computer. The attack affected Telefónica and several other large companies in Spain, as well as parts of the British National Health Service (NHS), where at least 16 hospitals had to turn away patients or cancel scheduled operations, FedEx, Deutsche Bahn, Honda, Renault, as well as the Russian Interior Ministry and Russian telecom MegaFon.
The attackers gave their victims a 7-day deadline from the day their
computers got infected, after which the encrypted files would be
Main article: Petya (malware)
See also: 2017 cyberattacks on Ukraine
Petya was first discovered in March 2016; unlike other forms of encrypting ransomware, the malware aimed to infect the master boot record, installing a payload which encrypts the file tables of the NTFS
file system the next time that the infected system boots, blocking the
system from booting into Windows at all until the ransom is paid. Check Point
reported that despite what it believed to be an innovative evolution in
ransomware design, it had resulted in relatively-fewer infections than
other ransomware active around the same time frame.
On 27 June 2017, a heavily modified version of Petya was used for a global cyberattack primarily targeting Ukraine (but affecting many countries).
This version had been modified to propagate using the same EternalBlue
exploit that was used by WannaCry. 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.
On 24 October 2017, some users in Russia
and Ukraine reported a new ransomware attack, named “Bad Rabbit”, which
follows a similar pattern to WannaCry and Petya by encrypting the
user’s file tables and then demands a Bitcoin payment to decrypt them. ESET believed the ransomware to have been distributed by a bogus update to Adobe Flash software. Among agencies that were affected by the ransomware were: Interfax, Odessa International Airport, Kiev Metro, and the Ministry of Infrastructure of Ukraine.
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.
Experts believed the ransomware attack was tied to the Petya attack in
Ukraine (especially because Bad Rabbit’s code has many overlapping and
analogical elements to the code of Petya/NotPetya, appending to CrowdStrike Bad Rabbit and NotPetya’s DLL (dynamic link library) share 67 percent of the same code) though the only identity to the culprits are the names of characters from the Game of Thrones series embedded within the code.
Security experts found that the ransomware did not use the
EternalBlue exploit to spread, and a simple method to vaccinate an
unaffected machine running older Windows versions was found by 24
Further, the sites that had been used to spread the bogus Flash
updating have gone offline or removed the problematic files within a few
days of its discovery, effectively killing off the spread of Bad
In 2016, a new strain of ransomware emerged that was targeting JBoss servers. This strain, named “SamSam“, was found to bypass the process of phishing or illicit downloads in favor of exploiting vulnerabilities on weak servers. The malware uses a Remote Desktop Protocol brute-force attack
to guess weak passwords until one is broken. 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, a major breach of security on the infrastructure of Atlanta.
Mohammad Mehdi Shah Mansouri (born in Qom, Iran in 1991) and Faramarz Shahi Savandi (born in Shiraz, Iran, in 1984) are wanted by the FBI for allegedly launching SamSam ransomware. The two have allegedly made $6 million from extortion and caused over $30 million in damages using the malware.
Syskey is a utility that was included with Windows NT-based operating systems to encrypt the user account database, optionally with a password. The tool has sometimes been effectively used as ransomware during technical support scams—where
a caller with remote access to the computer may use the tool to lock
the user out of their computer with a password known only to them. Syskey was removed from later versions of Windows 10 and Windows Server in 2017, due to being obsolete and “known to be used by hackers as part of ransomware scams”.
As with other forms of malware, security software (antivirus software)
might not detect a ransomware payload, or, especially in the case of
encrypting payloads, only after encryption is under way or complete,
particularly if a new version unknown to the protective software is distributed.
If an attack is suspected or detected in its early stages, it takes
some time for encryption to take place; immediate removal of the malware
(a relatively simple process) before it has completed would stop
further damage to data, without salvaging any already lost.
Security experts have suggested precautionary measures for
dealing with ransomware. Using software or other security policies to
block known payloads from launching will help to prevent infection, but
will not protect against all attacks As such, having a proper backup
solution is a critical component to defending against ransomware. Note
that, because many ransomware attackers will not only encrypt the
victim’s live machine but it will also attempt to delete any hot backups
stored locally or on accessible over the network on a NAS, it’s also critical to maintain “offline” backups of data stored in locations inaccessible from any potentially infected computer, such as external storage drives or devices that do not have any access to any network (including the Internet), prevents them from being accessed by the ransomware. Moreover, if using a NAS or Cloud storage, then the computer should have append-only permission to the destination storage, such that it cannot delete or overwrite previous backups.
Installing security updates issued by software vendors can mitigate the vulnerabilities leveraged by certain strains to propagate. Other measures include cyber hygiene − exercising caution when opening e-mail attachments and links, network segmentation, and keeping critical computers isolated from networks. Furthermore, to mitigate the spread of ransomware measures of infection control can be applied. Such may include disconnecting infected machines from all networks, educational programs, effective communication channels, malware surveillance[original research?] and ways of collective participation
File system defenses against ransomware
number of file systems keep snapshots of the data they hold, which can
be used to recover the contents of files from a time prior to the
ransomware attack in the event the ransomware doesn’t disable it.
- On Windows, the Volume shadow copy
(VSS) is often used to store backups of data; ransomware often targets
these snapshots to prevent recovery and therefore it is often advisable
to disable user access to the user tool VSSadmin.exe to reduce the risk that ransomware can disable or delete past copies.
- On Windows 10, users can add specific directories or files to
Controlled Folder Access in Windows Defender to protect them from
ransomware. It is advised to add backup and other important directories to Controlled Folder Access.
- File servers running ZFS
are almost universally immune to ransomware, because ZFS is capable of
snapshotting even a large file system many times an hour, and these
snapshots are immutable (read only) and easily rolled back or files
recovered in the event of data corruption. In general, only an administrator can delete (but cannot modify) snapshots.
- On Windows, the Volume shadow copy
File decryption and recovery
are a number of tools intended specifically to decrypt files locked by
ransomware, although successful recovery may not be possible.
If the same encryption key is used for all files, decryption tools use
files for which there are both uncorrupted backups and encrypted copies
(a known-plaintext attack in the jargon of cryptanalysis.
But, it only works when the cipher the attacker used was weak to begin
with, being vulnerable to known-plaintext attack); recovery of the key,
if it is possible, may take several days.
Free ransomware decryption tools can help decrypt files encrypted by
the following forms of ransomware: AES_NI, Alcatraz Locker, Apocalypse,
BadBlock, Bart, BTCWare, Crypt888, CryptoMix, CrySiS, EncrypTile,
FindZip, Globe, Hidden Tear, Jigsaw, LambdaLocker, Legion, NoobCrypt, Stampado, SZFLocker, TeslaCrypt, XData.
In addition, old copies of files may exist on the disk, which has
been previously deleted. In some cases, these deleted versions may
still be recoverable using software designed for that purpose.
The growing threat of malware
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Ransomware malicious software has evolved since its beginnings when
it was confined to one or two countries in Eastern Europe which then
spread across the Atlantic to the United States and Canada. The first versions of this type of malware used various techniques to disable the computers
by locking the victims system machine (Locker Ransomware) . Some
examples of how this ransomware works, include; locking the screen by
displaying a message from a branch of local law enforcement indicating
the user’s lines like “You have browsed illicit materials and must pay a
fine”. They were first seen in Russia by year 2009 claiming to be a
message from Microsoft. They also used to request a payment by sending
an SMS message to a premium rate number. The next variant displayed
pornographic image content and demanded payment for the removal of it.
In 2011 the tactics changed, the attackers started to use
electronic payment methods and they added more languages to the messages
which also changed based on the user’s location which was obtained by
geo-locating the user’s IP addresses.
Not only end users are affected by these attacks. Corporations,
private entities, government, and even hospitals are also affected. For
example, in healthcare (although 2015 was the year in which the largest
ePHI data breaches occurred according to the ONC) 2016 was the year that
ransomware started to increase exponentially in this market. According
to the 2017 Internet Security Threat Report from Symantec Corp,
ransomware affects not only IT systems but also patient care, clinical
operations, and billing. Online criminals have found “there was easy
money to be made in healthcare,” according to the Symantec report, which
was developed with data from insurance claims and the U.S. Department
of Health and Human Services (HHS).
Ransomware is growing rapidly across the internet users but also for the IoT environment
which creates a challenging problem to the INFOSEC while increasing the
attack surface area. They are evolving into more sophisticated attacks
and, they are becoming more resistant; at the same time, they are also
more accessible than ever. Today, for a cheap price, the attackers have
access to ransomware as a service. 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
At the end, the pressure to offer services to the patients and keep
their lives is so critical that they are forced to pay, and the attacker
knows that. The problem here is that by paying the ransom, they are
funding the cybercrime.
According to Symantec 2019 ISTR report, for the first time since
2013, in 2018 there was an observed decrease in ransomware activity with
a drop of 20 percent. Before 2017, consumers were the preferred
victims, but in 2017 this changed dramatically, it moved to the
enterprises. In 2018 this path accelerated with 81 percent infections
which represented a 12 percent increase. The common distribution method today is based on email campaigns.
Cyber awareness training is crucial to detecting attacks, whereas
technology cannot protect against careless or foolish behavior.
It is important for organizations to help their users recognize
malicious contact whereas ransomware is typically introduced through
email and social engineering
techniques to either download a file, provide key sensitive information
or take some action that will bring harm to the organization.
According to KnowBe4 Osterman report, there are number of approaches to
security awareness training that are practiced by organizations and
managed by security teams. There is the break room approach which are
special meetings periodically held to talk about security; monthly
security videos with short snippets of security information; simulated
phishing tests which target users with internal phishing messages; human
firewall approach where everyone is subject to simulated phishing and
those employees that are prone to attack are identified; and then there
is the do-nothing approach where cyber awareness training does not exist
in the organization.
An effective and successful cyber awareness training program must
be sponsored from the top of the organization with supporting policies
and procedures which effectively outline ramifications of
non-compliance, frequency of training and a process for acknowledgement
of training. Without sponsorship from the “C-level” executives the
training cannot be ignored. Other factors that are key to a successful
Cyber Awareness Training program is to establish a baseline identifying
the level of knowledge of the organization to establish where the users
are in their knowledge prior to training and after. Whichever approach
an organization decides to implement, it is important that the
organization has policies and procedures in place that provide training
that is up to date, performed frequently and has the backing of the
entire organization from the top down.
Investment in technology to detect and stop these threats must be
maintained, but along with that we need to remember and focus on our
weakest link, which is the user.
Freedom of speech challenges and criminal punishment
publication of proof-of-concept attack code is common among academic
researchers and vulnerability researchers.
It teaches the nature of the threat, conveys the gravity of the issues,
and enables countermeasures to be devised and put into place. However,
lawmakers with the support of law-enforcement bodies are contemplating
creation of ransomware illegal. In the state of Maryland, the original
draft of HB 340 made it a felony to create ransomware, punishable by up
to 10 years in prison. However, this provision was removed from the final version of the bill.
A minor in Japan was arrested for creating and distributing ransomware code.
Young and Yung have had the ANSI C source code to a ransomware cryptotrojan on-line, at cryptovirology.com, since 2005 as part of a cryptovirology book being written. The source code to the cryptotrojan is still live on the Internet and is
associated with a draft of Chapter 2.
Ransomware arrests and convictions
British student Zain Qaiser (24) from Barking, London was jailed for
more than six years at Kingston Crown Court for his ransomware attacks
He is said to have been “the most prolific cyber criminal to be
sentenced in the UK”. He became active when he was only 17. He contacted
the Russian controller of one of the most powerful attacks, believed to
be the Lurk malware gang, and arranged for a split of his profits. He
also contacted online criminals from China and the US to move the money.
For about one and a half years, he posed as a legitimate supplier of
online promotions of book advertising on some of the world’s most
visited legal pornography websites. Each of the adverts that was
promoted on the websites contained the Reveton strain of the malicious
“Angler Exploit Kit (AEK)”
code that seized control of the machine. Investigators discovered about
£700,000 of earnings, although his network may have earned more than
£4m. He may have hidden some money using cryptocurrencies. The
ransomware would instruct victims to buy GreenDot MoneyPak
vouchers, and enter the code in the Reveton panel that being displayed
on the screens. This money entered a MoneyPak account managed by
Qaiser, who would then deposit the voucher payments into an American
co-conspirator’s (Raymond Odigie Uadiale Uadiale, who was then a student
at Florida International University
during 2012 and 2013 and later worked for Microsoft) debit card, who
would convert the money into Liberty Reserve digital currency and
deposit it into Qaiser’s Liberty Reserve account.
A breakthrough in this case came occurred in May 2013 when authorities from several countries seized the Liberty Reserve
servers, obtaining access to all the transactions and account history.
Qaiser was running encrypted virtual machines on his Macbook Pro with
both Mac and Windows operating systems.
He could not be tried earlier because he was sectioned under the UK
Mental Health Act at Goodmayes hospital (where he was found to be using
the hospital wifi to access his advertising sites.) His lawyer claimed
that Qaiser had suffered from mental illness. Russian police arrested 50 members of the Lurk malware gang in June 2016. Raymond Odigie Uadiale, a naturalized US citizen of Nigerian descent, was jailed for 18 months.
Muna; den Hartog, Frank; Sitnikova, Elena (2019). “Targeted Ransomware:
A New Cyber Threat to Edge System of Brownfield Industrial Internet of
Things”. IEEE Internet of Things Journal. 6 (4): 7137–7151. doi:10.1109/JIOT.2019.2914390.
Iranian Men Indicted for Deploying Ransomware to Extort Hospitals,
Municipalities, and Public Institutions, Causing Over $30 Million in
Losses” (Press release). United States Department of Justice. 28 November 2018. Retrieved 11 December 2018.
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American businesses since the meltdown of 2008. Clearwater, FL: KnowBe4.
Research, Inc. (October 2018). “Best Practices for Implementing
Security Awareness Training” [Whitepaper]. KnowBe4. Retrieved
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- Richet, Jean-Loup (July 2015). “Extortion on the Internet: the Rise of Crypto-Ransomware” (PDF). Harvard University.
- Media related to Ransomware at Wikimedia Commons
- Incidents of Ransomware on the Rise – Federal Bureau of Investigation