ICS-Targeting Snake Ransomware Isolates Infected Systems Before Encryption

Recent samples of the Snake ransomware were observed isolating the infected systems to ensure that nothing interferes with the file encryption process, security researchers warn.

Initially detailed in January this year, Snake (also known as EKANS) has emerged as a prevalent threat to industrial control systems (ICS), due to the targeting of processes specific to these environments. The ransomware is believed to be responsible for the Honda cyber-incident last month.

One of the main characteristics of Snake is the killing of processes from a predefined list, including ICS-related processes, to encrypt resources associated with them in an effort to further entice victims into paying the ransom to restore affected systems.

As part of more recent attacks, the ransomware has taken the malicious activity one step further, through attempting to isolate the compromised systems before starting the file encryption process.

For that, Snake’s developers packed the threat with the ability to enable and disable the firewall and use specific commands to block unwanted connections to the system.

“Before initiating the encryption, Snake will utilize the Windows firewall in order to block any incoming and outgoing network connections on the victim’s machine that aren’t configured in the firewall. Windows built-in netsh tool will be used for this purpose,” cybersecurity firm Deep Instinct explains.

Furthermore, the malware would then hunt for processes that might interfere with the encryption process and kill them, including those related to industrial applications, security tools, and backup solutions. It also deletes shadow copies to prevent recovery operations.

Just as before, however, the ransomware avoids encrypting system-critical folders and files.

While analyzing Snake’s behavior, Fortinet also discovered that the malicious tool turns the firewall off after the encryption process has been completed.

Furthermore, the security firm notes that the ransomware appears to prefer domain controllers on the network, and that it specifically searches for them following initial compromise. For that, it uses a WMI query to determine the roles of various machines on the network.

If successful at infecting a domain controller, Snake “can affect security authentication requests within the network domain, thereby severely impacting networked users,” Fortinet points out.

Related: Honda Ransomware Confirms Findings of Industrial Honeypot Research

Related: New Snake Ransomware Targets ICS Processes

Related: Double Extortion: Ransomware’s New Normal Combining Encryption with Data Theft