Category Archives: Randsomware

New Cry Ransomware Strain Has Unusual Advanced Features

“A new ransomware that pretends to be from a fake organization called the Central Security Treatment Organization has been discovered by security researcher MalwareHunterTeam.  When the Central Security Treatment Organization, or Cry, Ransomware infects a computer it will encrypt a victim’s files and then append the .cry extension to encrypted files. It will then demand approximately 1.1 bitcoins, or $625 USD, in order to get the decryption key.”

Reported – Larry Abrams at Bleepingcomputer

Abrams continued: “For example, like Cerber, this ransomware will send information about the victim to the Command & Control server using UDP. Furthermore, it will also use public sites such as Imgur.com and Pastee.org to host information about each of the victims. Last, but not least, it will query the Google Maps API to determine the victim’s location using nearby wireless SSIDs.”

This strain is clearly created by experienced coders that know what they are doing. Just look at the list of advanced features this Version 1.0 came out with. Looking at the resources spent to create this strain, you can expect a massive wave of attacks to follow soon. These bad guys have the resources and then some:

  • Uses UDP to communicate with the Command & Control Server to evade detection
  • Uses social networks to upload and host information about the victims using fake PNG files
  • Queries Google Maps API to identify victim location using nearby wireless SSID’s
  • Deletes the system Shadow Volume Copies
  • Stays persistent after reboots Uses TOR payment site that requires the victim’s personal ID from ransomnote
  • Has functioning support page to communicate with the criminals
  • Includes a free (drag & drop, imagine that) decryption of one file to prove the files can be decrypted

 

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Locky Ransomware Encrypts Files Even When Machine Is Offline

The Locky ransomware has added a fallback mechanism in the latest strain of  malware created for situations where the code can’t reach its Command & Control server.

Researchers from antivirus vendor Avira blogged about this version which starts encrypting files even when it cannot request a unique encryption key from the Command & Control server because the computer is offline or a firewall blocks outgoing communications.

Calling the mothership is normally required for ransomware that uses public key cryptography. And actually, if the code is unable to call home to a Command & Control server after they infect a new machine, most ransomware does not start the encryption process and is dead in the water.

Why? The encryption routine needs unique public-private key pairs that are generated by the Command & Control server for each infection. How does this work? Here is a simplified sequence of events.

  1. The ransomware program generates a local encryption key and uses an algorithm like AES (Advanced Encryption Standard) to encrypt files with certain extensions.
  2. It reaches out to a Command & Control server and asks that machine to generate an RSA key pair for the newly infected system.
  3. The public key of that pair is sent back to the infected machine and used to encrypt the AES encryption key from step 1. The private key, (needed to decrypt what the public key encrypted), stays on the Command & Control server and is the key that you get when you pay the ransom and is used for decryption.

As you see, a lot of ransomware  strains are useless if a firewall detects their attempt to call home and blocks it as suspicious. There is another scenario however…

As damage control, organizations also cut off a computer from the network the moment a ransomware infection is detected. They might even take the whole network offline until they can investigate if other systems have also been infected.

The silver lining? If someone pays the ransom and gets the private key, that key will work for all other offline victims as well, so expect a free decryptor to become available in the near future.

 

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PETYA Crypto-ransomware Overwrites MBR to Lock Users Out of Their Computers

As if encrypting files and holding them hostage is not enough, cybercriminals who create and spread crypto-ransomware are now resorting to causing blue screen of death and putting their ransom notes at system startup—as in, even before the operating system loads. Imagine turning on your computer and instead of the usual Windows icon loading, you get a flashing red and white screen with a skull-and-crossbones instead.

petya_figure1

This is the routine of a new crypto-ransomware variant dubbed “Petya”. Not only does this malware have the ability to overwrite the affected system’s master boot record (MBR) in order to lock users out, it is also interesting to note that it is delivered to victims via a legitimate cloud storage service (in this case, via Dropbox).

This isn’t the first time that malware has abused a legitimate service for its own gain; however, this is the first time (in a long time) that leads to crypto-ransomware infection. It is also a departure from the typical infection chain, wherein the malicious files are attached to emails or hosted in malicious sites and delivered by exploit kits.

Infection Routine

Reportedly, Petya is still distributed via email. Victims would receive an email tailored to look and read like a business-related missive from an “applicant” seeking a position in a company. It would present users with a hyperlink to a Dropbox storage location, which supposedly would let the user download said applicant’s curriculum vitae (CV).

In samples analyzed, the Dropbox folder the link points contains two files: a self-extracting executable file, which purports to be the CV, and the applicant’s photo. Further digging revealed that the photo is a stock image that is most likely used without permission from the photographer.

petya_archive

Of course, the file downloaded isn’t actually a resume at all, but rather a self-extracting executable file which would then unleash a Trojan onto the system. The Trojan then blinds any antivirus programs installed before downloading (and executing) the Petya ransomware.

Infection Symptoms

Once executed, Petya overwrites the MBR of the entire hard drive, causing Windows to crash and display a blue screen. Should the user try to reboot his PC, the modified MBR will prevent him from loading Windows normally and instead greet him with an ASCII skull and an ultimatum: pay up with a certain amount of bitcoins or lose access to your files and computer.

Another thing to point out here is that the edited MBR also disallows restarting in Safe Mode.

The user is then given explicit instructions on how to do this, just like any crypto-ransomware currently making the rounds: a list of demands, a link to the Tor Project and how to get to the payment page using it, and a personal decryption code.

petya_figure2

Looking at its very professionally-designed Tor website, we discover that its ransom price is currently at 0.99 Bitcoins (BTC), or US$431 – and that said price would be doubled if the on-screen deadline for payment is missed.

petya_figure3

 

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Weird New Cerber Ransomware Speaks To Its Victims

There is a new strain of ransomware called Cerber that takes creepiness to the next level.

It drops three files on the victim’s desktop named “# DECRYPT MY FILES #.” These files contain instructions about the ransom amount and how to pay it. One of the files is your standard TXT format, one is HTML and the third is plain weird. It contains a Visual Basic Script, which contains text-to-speech code that converts text into an audio message.

“When the above script is executed, your computer will speak a message stating that your computer’s files were encrypted and will repeat itself numerous times,” Larry Abrams from Bleepingcomputer said in a blog post. They have a sample in that post you can listen to.

Cerber’s criminal developers are selling the tool as Ransomware-as-a-Service (RaaS) so that practically anyone can use it without any coding experience. It is easy to find out where this new strain originated.  When first run, Cerber will check to see if the victim is from a particular country. If the computer appears to be from any of the following countries, it will terminate itself and not encrypt the computer: Armenia, Azerbaijan, Belarus, Georgia, Kyrgyzstan, Kazakhstan, Moldova, Russia, Turkmenistan, Tajikistan, Ukraine, Uzbekistan.

Yup, that was easy. Another Eastern European cyber gang with another strain.

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