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Cyberthreat Research

Increase in PYSA Ransomware Targeting Education Institutions

Fortify Security Team
Mar 16, 2021

FBI reporting has indicated a recent increase in PYSA ransomware targeting education institutions in 12 US states and the United Kingdom. PYSA, also known as Mespinoza, is a malware capable of exfiltrating data and encrypting users’ critical files and data stored on their systems. The unidentified cyber actors have specifically targeted higher education, K-12 schools, and seminaries. These actors use PYSA to exfiltrate data from victims prior to encrypting victim’s systems to use as leverage in eliciting ransom payments.

Technical Details
Since March 2020, the FBI has become aware of PYSA ransomware attacks against US and foreign government entities, educational institutions, private companies, and the healthcare sector by unidentified cyber actors. PYSA typically gains unauthorized access to victim networks by compromising Remote Desktop Protocol (RDP) credentials and/or through phishing emails. The cyber actors use Advanced Port Scanner and Advanced IP Scanner to conduct network reconnaissance, and proceed to install open source tools, such as PowerShell Empire, Koadic, and Mimikatz. The cyber actors execute commands to deactivate antivirus capabilities on the victim network prior to deploying the ransomware.

The cyber actors then exfiltrate files from the victim’s network, sometimes using the free opensource tool WinSCP , and proceed to encrypt all connected Windows and/or Linux devices and data, rendering critical files, databases, virtual machines, backups, and applications inaccessible to users. In previous incidents, cyber actors exfiltrated employment records that contained personally identifiable information (PII), payroll tax information, and other data that could be used to extort victims to pay a ransom.

Upon malware execution, a detailed ransom message is generated and displayed on the victim’s login or lock screen. The ransom message contains information on how to contact the actors via email, displays frequently asked questions (FAQs), and offers to decrypt the affected files. If the ransom is not met, the actors warn that the information will be uploaded and monetized on the darknet. Additionally, the malware is dropped in a user folder, such as C:\Users\%username%\Downloads\. Observed instances of the malware showed a filename of svchost.exe, which is most likely an effort by the cyber actors to trick victims and disguise the ransomware as the generic Windows host process name. In some instances, the actors removed the malicious files after deployment, resulting in victims not finding any malicious files on their systems.

The cyber actors have uploaded stolen data to MEGA.NZ, a cloud storage and file sharing service, by uploading the data through the MEGA website or by installing the MEGA client application directly on a victim’s computer. However, in the past actors have used other methods of exfiltrating data that leaves less evidence of what was stolen.

Indicators
The following are characteristics of the compromise:

Information Requested

The FBI does not encourage paying ransoms. Payment does not guarantee files will be recovered. It may also embolden adversaries to target additional organizations, encourage other criminal actors to engage in the distribution of ransomware, and/or fund illicit activities. However, the FBI understands that when victims are faced with an inability to function, all options are evaluated to protect shareholders, employees and customers. Regardless of whether your organization decided to pay the ransom, the FBI urges you to report ransomware incidents to your local FBI field office or the FBI’s Internet Crime Complaint Center (IC3) (https://ic3.gov). Doing so provides the FBI with critical information needed to prevent future attacks by identifying and tracking ransomware attackers and holding them accountable under U.S. law. Your Fortify 24×7 Incident Response team will be able to assist with FBI engagement on ongoing communication.

Recommended Mitigations

  • Regularly back up data, air gap, and password protect backup copies offline. Ensure copies of critical data are not accessible for modification or deletion from the system where the data resides.
  • Implement network segmentation.
  • Implement a recovery plan to maintain and retain multiple copies of sensitive or proprietary data and servers in a physically separate, segmented, secure location (i.e., hard drive, storage device, the cloud).
  • Install updates/patch operating systems, software, and firmware as soon as they are released.
  • Use multifactor authentication where possible.
  • Regularly, change passwords to network systems and accounts, and avoid reusing passwords for different accounts. Implement the shortest acceptable timeframe for password changes.
  • Disable unused remote access/RDP ports and monitor remote access/RDP logs.
  • Audit user accounts with administrative privileges and configure access controls with least privilege in mind.
  • Install and regularly update anti-virus and anti-malware software on all hosts.
  • Only use secure networks and avoid using public Wi-Fi networks. Consider installing and using a VPN.
  • Consider adding an email banner to messages coming from outside your organizations.
  • Disable hyperlinks in received emails.
  • Focus on awareness and training. Provide users with training on information security principles and techniques as well as overall emerging cybersecurity risks and vulnerabilities (i.e., ransomware and phishing scams).

 

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