Emerging Malware Trends: Ransomware

The mutation of malware is happening very rapidly where new types of techniques are evolving to raise money for hackers. Ransomware is a mutation of scareware, where the hacker hijacks a PC by encrypting all its files and demands ransom to unlock or decrypt the files. The infected PC may not send spam mails or track sensitive information for its creator. It is worse than that.

The ransomware came into radar screen of security researchers in 2009, where a Vundo Trojan is found to encrypt all personal files and the users are asked to pay for the key to decrypt them. The earliest form of scareware just used to make people pay for useless software and fake antivirus. The hackers were able to make it sophisticated enough to hold a PC for ransom. Apart from encryption, the ransomware might just block access to all the applications of the system, asking the user to buy a license in order to fix the problem. The hacker might even entice with a 30-day-money-back guarantee message, which is false.

Techniques used to install Ransomware:
Ransomware is just one kind of malware. So all the methods been used to install it in your PC are similar to that of any virus or trojan infection. However, the actual talent of the hacker lies in making the victim to pay the ransom. Heavy techniques of social engineering are used here. The following are a few techniques used by hackers of ransomware:

  • Spam emails with malicious files. The malicious files contain code that exploits the vulnerabilities in the software applications. The code then takes control of the PC denying the access to applications and files.
  • The exploitation of the vulnerabilities in browser due to opening malicious web pages. Then an in-line adult advertisement, is shown in every web page the user opens. It covers main part of the web page which the user can’t get rid off. The text written on the banner will be in a foreign language. The user is also asked to send SMS to a premium rate phone number, to get special code that will make the ad disappear and also receive access to an archive of explicit videos.
  • The user visiting a spoofed site may suddenly see a message that his PC is infected and to download a tool to get rid off it. The downloaded file actually contains ransomware.
  • A malicious .dll file is smuggled into the PC, which manipulates the working of parental controls or Web content filtering features of the PC. When the user tries to open even legitimate sites like Youtube, Facebook, etc from browser, a message in red background is displayed saying: “Restricted Site! This web site is restricted based on your security preferences. Your system is infected. Please activate your antivirus software.” The domains will be allowed to access only of the user purchases a fake AV from the hacker.
  • Another technique includes manipulation of the master boot record, preventing the booting into operating system. A message is displayed saying that the access to the PC is blocked and the user is asked to visit a site. In the site, he will be asked to pay for getting back access to the PC. However, in such cases, the user can just bypass the prompt and restore the master boot record. Rescue disks are very much helpful in these cases.
  • An Instant messaging worm is found to block access to the Facebook account in the infected PC. The message looks as if Facebook itself has blocked the account. The victim is asked to complete answers for a survey within a short period of time. Amid of the survey the victim is tricked to subscribe premium rate services on their mobile phones.
  • Adult websites are main hub for the malware downloads. For example, a piece of ransomware identified as WORM_RIXBOT.A, was downloaded over 137,000 times from a single adult website, in December alone. This worm prevents users from accessing their desktops and asks them to send a text message to a premium number in order to receive unlock code.
  • The recent Japan earthquake also triggered few ransomware infections. The emails sent to the users contain links to fake news articles from where the malware installs in the PC. Then the access to the desktop is seized with a message claiming to be from Federal police saying that some illegal activities are discovered on PC and pay some fine within the given time of they don’t want their hard drive erased.
  • The recent technique of ransomware involves display of a windows reactivation message. The victim is given a toll-free phone number for getting the reactivation code. However, the call will not be free and the hacker is paid indirectly from the victim’s pocket.

In most of the above instances, the files on the hard drive are encrypted. For decrypting the files, a private key is required from the hacker. In such cases, the users must plug off their PC, immediately after seeing the encryption message to stop further encryption of files. This makes sure to save at least some amount of data from getting encrypted. The hard drive should then be removed and installed as a secondary drive in another PC to copy unaffected files into some other storage device. Regular backups are key here to minimize the impact. The encryption can then be cracked down with the help of some security expert.

Tags: ransomware

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