![](https://web.archive.org/web/20120506060706im_/http://upload.wikimedia.org/wikipedia/en/thumb/c/ca/Metropolitan_Police_ransomware_scam.jpg/220px-Metropolitan_Police_ransomware_scam.jpg)
Ransomware (also referred to in some cases as cryptoviruses, cryptotrojans or cryptoworms) comprises a class of malware which restricts access to the computer system that it infects, and demands a ransom paid to the creator of the malware in order for the restriction to be removed. Some forms of ransomware encrypt files on the system's hard drive, while some may simply lock the system and display messages intended to coax the user into paying. Modern ransomware attacks were initially popular within Russia, but in recent years there have been an increasing number of ransomware attacks targeted towards other countries, such as Australia, Germany, and the United States among others.[1]
Operation
Ransomware typically propagates as a conventional computer worm, entering a system through, for example, a vulnerability in a network service or a downloaded file. The program will then run a payload which will begin to encrypt personal files on the hard drive.[2][3][4] More sophisticated ransomware may hybrid-encrypt the victim's plaintext with a random symmetric key and a fixed public key. The malware author is the only party that knows the needed private decryption key.[5] Some ransomware payloads do not use encryption. In these cases, the payload is simply an application designed to effectively restrict interaction with the system, typically by overriding explorer.exe in the Windows registry as the default shell.[6] Some ransomware payloads may instead modify the master boot record, not allowing the operating system to start at all until it is repaired[7]
Ransomware payloads, especially ones which do not encrypt files, utilize elements of scareware to coax the user into paying for its removal. The payload may, for example, display notices purportedly issued by companies or law enforcement agencies which falsely claim that the user's system had been used for illegal activities, or contains illegal content such as pornography and unlawfully obtained software.[8][9] Some ransomware payloads imitate Windows XP's product activation notices, falsely claiming that their computer's Windows installation is counterfeit or requires re-activation.[10]
In any case, the ransomware will attempt to extort money from the system's user by forcing them to purchase either a program to decrypt the files it had encrypted, or an unlock code which will remove the locks it had applied. These payments are often delivered using either a wire transfer, premium-rate text messages,[11] or through an online payment voucher service such as Ukash or Paysafecard.[1][12][13]
History
The first known ransomware was the 1989 "PC Cyborg" trojan written by Joseph Popp, which triggered a payload claiming that the user's license to use a certain piece of software had expired, encrypted file names on the hard drive, and required the user to pay 189 United States dollars to "PC Cyborg Corporation" in order to unlock the system. Researchers discovered, however, that Popp had used symmetric cryptography, which was easily broken. 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.[14] The notion of using public key cryptography for such attacks was introduced in 1996 by Alex Young and Moti Yung, who presented a proof-of-concept cryptovirus for the Macintosh SE/30 using RSA and TEA. Young and Yung referred to this attack as 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.[2]
Examples of extortionate ransomware reappeared in May 2005.[15] By mid-2006, worms 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.[16] In June 2008, a variant known as Gpcode.AK used a 1024-bit RSA key, which was believed to be large enough to be computationally infeasible to break without a concerted distributed effort.[5][17][18][19]
In August 2010, Russian authorities arrested ten individuals had been connected to WinLock, a ransomware which displayed pornographic images and asked users to send a premium-rate text message costing around US$10 to receive a code which can unlock their machines. The scam hit a large number of users across Russia and neighboring countries—reportedly earning the group over US$16 million. Unlike the previous Gpcode worms, WinLock did not use encryption, using a more trivial process of simply requiring an activation code.[9][20]
In 2011, a new ransomware attack surfaced which claimed that a system's Windows installation would have to be re-activated due to "[being a] victim of fraud" or an internal error. While an online activation option is offered much like the actual Windows activation process, it is unavailable, requiring the user to call one of six international numbers to input a 6-digit code. While the call was claimed to 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 long distance charges.[10]
In 2012, a ransomware attack aimed at British users surfaced, containing notices purportedly from the Metropolitan Police stating that the user's system was under investigation since it contained pornographic videos and that "spam messages with terrorist motives" had been sent from it. To increase its realism, the screen the ransomware displayed also showed the computer's IP address as well. In order to unlock the system, the notice informed the user that they would have to pay a fine using the widely used Ukash or Paysafecard payment platforms—which do not require the disclosure of personal information in order to be used, thus reducing the amount of evidence. Localized variants of this ransomware also surfaced in other European countries. In a statement warning of the scam, the Metropolitan Police clarified that they would not lock a computer in such a way as part of an investigation.[1][8] A similar ransomware targeted Italian users, with notices allegedly from Guardia di Finanza and connecting to IP addresses located in Russia.[21]
References
- ^ a b c Dunn, John E.. "Ransom Trojans spreading beyond Russian heartland". TechWorld. http://news.techworld.com/security/3343528/ransom-trojans-spreading-beyond-russian-heartland/. Retrieved 10 March 2012.
- ^ a b Young, A.; Moti Yung (1996). "Cryptovirology: extortion-based security threats and countermeasures". Proceedings 1996 IEEE Symposium on Security and Privacy. pp. 129. doi:10.1109/SECPRI.1996.502676. ISBN 0-8186-7417-2.
- ^ Adam Young (2005). "Building a Cryptovirus Using Microsoft's Cryptographic API". Information Security: 8th International Conference, ISC 2005 (Springer-Verlag): pp. 389–401.
- ^ Young, Adam (2006). "Cryptoviral Extortion Using Microsoft's Crypto API: Can Crypto APIs Help the Enemy?". International Journal of Information Security (Springer-Verlag) 5 (2): 67–76.
- ^ a b Naraine, Ryan (2008-06-06). "Blackmail ransomware returns with 1024-bit encryption key". ZDnet. http://blogs.zdnet.com/security/?p=1251. Retrieved 2009-05-03.
- ^ "Ransomware: Fake Federal German Police (BKA) notice". SecureList (Kaspersky Lab). http://www.securelist.com/en/blog/6155/Ransomware_Fake_Federal_German_Police_BKA_notice. Retrieved 10 March 2012.
- ^ "And Now, an MBR Ransomware". SecureList (Kaspersky Lab). http://www.securelist.com/en/blog/208188032/And_Now_an_MBR_Ransomware. Retrieved 10 March 2012.
- ^ a b "Police warn of extortion messages sent in their name". Helsingin Sanomat. http://www.hs.fi/english/article/Police+warn+of+extortion+messages+sent+in+their+name/1329103586716. Retrieved 9 March 2012.
- ^ a b McMillian, Robert. "Alleged Ransomware Gang Investigated by Moscow Police". PC World. http://www.pcworld.com/businesscenter/article/204577/alleged_ransomware_gang_investigated_by_moscow_police.html. Retrieved 10 March 2012.
- ^ a b "Ransomware squeezes users with bogus Windows activation demand". Computerworld. http://www.computerworld.com/s/article/9215711/Ransomware_squeezes_users_with_bogus_Windows_activation_demand. Retrieved 9 March 2012.
- ^ Danchev, Dancho (2009-04-22). "New ransomware locks PCs, demands premium SMS for removal". ZDNet. http://blogs.zdnet.com/security/?p=3197. Retrieved 2009-05-02.
- ^ "Ransomware plays pirated Windows card, demands $143". Computerworld. http://www.computerworld.com/s/article/9219745/Ransomware_plays_pirated_Windows_card_demands_143. Retrieved 9 March 2012.
- ^ Cheng, Jacqui (2007-07-18). "New Trojans: give us $300, or the data gets it!". Ars Technica. http://arstechnica.com/security/news/2007/07/new-trojans-give-us-300-or-the-data-gets-it.ars. Retrieved 2009-04-16.
- ^ Kassner, Michael. "Ransomware: Extortion via the Internet". TechRepublic. http://www.techrepublic.com/blog/security/ransomware-extortion-via-the-internet/2976. Retrieved 10 March 2012.
- ^ Schaibly, Susan (2005-09-26). "Files for ransom". Network World. http://www.networkworld.com/buzz/2005/092605-ransom.html?page=3. Retrieved 2009-04-17.
- ^ Leyden, John (2006-07-24). "Ransomware getting harder to break". The Register. http://theregister.co.uk/2006/07/24/ransomware/. Retrieved 2009-04-18.
- ^ Lemos, Robert (2008-06-13). "Ransomware resisting crypto cracking efforts". SecurityFocus. http://www.securityfocus.com/news/11523. Retrieved 2009-04-18.
- ^ Krebs, Brian (2008-06-09). "Ransomware Encrypts Victim Files With 1,024-Bit Key". Washington Post. http://voices.washingtonpost.com/securityfix/2008/06/ransomware_encrypts_victim_fil.html. Retrieved 2009-04-16.
- ^ "Kaspersky Lab reports a new and dangerous blackmailing virus". Kaspersky Lab. 2008-06-05. http://www.kaspersky.com/news?id=207575650. Retrieved 2008-06-11.
- ^ Leyden, John. "Russian cops cuff 10 ransomware Trojan suspects". The Register. http://www.theregister.co.uk/2010/09/01/ransomware_trojan_suspects_cuffed/. Retrieved 10 March 2012.
- ^ "(In Italian) Trojan.Win32.FakeGdf.A Malware che si spaccia per la Guardia di Finanza.". http://www.anti-phishing.it/phishing/2011/12/18/1957. Retrieved 21 March 2012.
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