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Cactus

Posted: December 24, 2023
from Cybersecurity Glossary
Aliases:
Cactus virus
Aliases:
Platform:
Windows , VPN Software Affected
Variants:
Win64:Trojan-gen, Generic.Ransom.Cactus.A.6A6CBCEA,Win64/Filecoder.Cactus.A, Trojan- Ransom. Win32. Cactus.d, Ransom: Win32/Cactus.LKV!MTB
Damage:
Inaccessible Files, Data Theft, Ransom Demands, Network Spread
Risk Level:
Very High!

Cactus ransomware capitalizes on vulnerabilities within certain VPN software to infiltrate corporate networks. After breaching a company's system, the perpetrators behind Cactus establish fraudulent user accounts and execute the ransomware, encrypting files and demanding payment for a decryption key. Initially identified in March 2023, Cactus has gained notoriety for its ability to elude antivirus detection through self-encryption.

Possible symptoms

  • Unexpected encryption of files with a distinct file extension.
  • Display of ransom messages demanding payment for file decryption.
  • Creation of unauthorized user accounts within the network.
  • Unusual network activity, including increased data transfer volumes during the encryption process.

Sources of the infection

  • Exploitation of vulnerabilities in specific VPN software versions.
  • Phishing emails containing malicious attachments or links leading to the ransomware payload.
  • Compromised external devices, such as USB drives, carrying the malware into the network.
  • Drive-by downloads from compromised websites hosting exploit kits targeting VPN vulnerabilities.
  • Malicious network traffic attempting to exploit weaknesses in network security protocols.

Overview

Cactus ransomware, also known as the Cactus virus, is a formidable cyber threat categorized as a ransomware variant. Operating with a focus on exploiting vulnerabilities within specific VPN software, Cactus has emerged as a significant danger to corporate networks. The damage potential of this malicious software includes rendering files inaccessible, data theft, ransom demands, and network spread.

The Cactus ransomware, first identified in March 2023, exhibits a unique modus operandi. It gains access to corporate networks by leveraging weaknesses in targeted VPN software. Once infiltrated, the perpetrators establish fraudulent user accounts within the system and initiate the ransomware, encrypting files and subsequently demanding payment for a decryption key. Notably, Cactus has gained infamy for its ability to evade antivirus detection through self-encryption, adding to its sophisticated nature.

Common symptoms of a Cactus infection include the unexpected encryption of files with a distinct file extension, the display of ransom messages demanding payment for file decryption, the creation of unauthorized user accounts within the network, and unusual network activity characterized by increased data transfer volumes during the encryption process.

Cactus employs various infiltration methods, including the exploitation of vulnerabilities in specific VPN software versions, phishing emails containing malicious attachments or links leading to the ransomware payload, compromised external devices such as USB drives carrying the malware into the network, drive-by downloads from compromised websites hosting exploit kits targeting VPN vulnerabilities, and malicious network traffic attempting to exploit weaknesses in network security protocols.

For those suspecting a Cactus infection, immediate actions are crucial. Isolating the infected system from the network to prevent further spread, not paying the ransom but reporting the incident to cybersecurity teams or law enforcement, identifying patient zero and the initial point of infection, and restoring affected files from secure backups after removing the malware are recommended steps.

Preventing Cactus infections requires a proactive approach. This includes regularly updating and patching VPN software to address vulnerabilities, employing network segmentation to limit lateral movement in case of a breach, implementing strong access controls and user authentication mechanisms, conducting regular security audits and penetration testing, and training employees on recognizing phishing attempts and social engineering tactics.

🤔 What to do?

If you suspect a Cactus infection:

  1. Isolate the infected system from the network to prevent further spread.
  2. Do not pay the ransom; instead, report the incident to your cybersecurity team or law enforcement.
  3. Attempt to identify patient zero and the initial point of infection.
  4. Restore affected files from secure backups after removing the malware.

🛡️ Prevention

To prevent Cactus infections:

  • Regularly update and patch VPN software to address vulnerabilities.
  • Employ network segmentation to limit lateral movement in case of a breach.
  • Implement strong access controls and user authentication mechanisms.
  • Conduct regular security audits and penetration testing.
  • Train employees on recognizing phishing attempts and social engineering tactics.

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