Petya Ransomware Cripples Systems Like WannaCry – Worldwide

Morey Haber, June 27th, 2017

Petya Ransomware

It is another week, and another widespread report of a significant cyber-attack across Ukraine which is also affecting organizations in Russia and throughout Europe. This appears to be another ransomware attack, this time using the Petya malware – similar to the recent than WannaCry ransomware attack. However, Petya differs by attacking the whole file system at a very low level rather than file-by-file.

Researchers in 2016 discovered that turning your PC off after initial infection—which causes BSOD (Blue-Screen of Death)—can potentially recover your system because encryption of the drive hasn’t started at that point. However, if you reboot your system then it will immediately start the encryption which will quickly render the system unrecoverable. Unfortunately, this variation of Petya ransomware makes this mitigation path nearly impossible to utilize.

About Petya Ransomware

The initial ransomware payload has been modified and now contains these new traits:

  • Petya spreads through malicious Office attachments and email. This gets through the front door and onto any target system that can be exploited via social engineering.
  • Once the malware is installed, it looks for other systems to exploit using EternalBlue. This is the same vulnerability as WannaCry to exploit any system via lateral movement.
  • Petya also contains malware to scrape memory and the file system for passwords and execute psexec against remote targets to propagate the infection. This will compromise hosts even if they are patched for EthernalBlue and leverage administrator credentials it discovers during its interrogation of the system.
  • Encryption is at a low level using the Master File Tree tables for NTFS and overwrites the Master Boot Record (MBR) with a ransomware warning. This is why a reboot must be done instantly or the MBR can be compromised.

It’s impossible to say who is behind this attack. Previously, Ukraine has pointed to Russia as the culprit but in this attack Russian organizations have also been affected. With European companies also impacted it’s likely this is a purely financial attack looking for the broadest reach without specific targeting of countries or organizations.

What to do

As with other cyber attacks of this nature, this highlights the importance of getting the basics of cybersecurity right starting with patching vulnerabilities with known exploits first and ensuring your teams understand the importance of not opening attachments that were not expected.

The BeyondTrust team has identified that the initial exploitation does require administrator rights to infect the system and drop the initial malware associated with Petya. If you are running a least privilege solution, have removed end user administrator rights, or are only trusting digitally signed applications, initial reports indicate UAC will prompt before executing the malware.

Peyta Ransomware

This should stop the initial infection. However, once the first machine is compromised, administrator rights are not needed to propagate the worm due to the severity of the vulnerability and methods used for exploitation. It is still unknown whether newer systems with SecureBoot are immune to this ransomware at initial inception, or if the exploitation has been improved to target Windows 10 machines as well.

As BeyondTrust has recommended in the past, the best way to mitigate the risks from ransomware are implementing the basics in cyber security hygiene:

For more information on how BeyondTrust can help mitigate the risks Petya, and other ransomware, contact us today.