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What is Clop Ransomware? – Security Boulevard | #hacking | #cybersecurity | #infosec | #comptia | #pentest | #ransomware


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Clop ransomware is part of the infamous Cryptomix family that targets systems with security loopholes. Clop ransomware can encrypt files and append the .Clop extension. Its name is taken from the Russian word ‘Klop,’ which means bed bug– a bug from the Cimex family that feeds on human blood at night.

This ransomware was first observed by Michael Gillespie in 2019. It was recently involved in exploiting security loopholes in MOVEit Transfer and MOVEit Cloud to extort $500 million from various enterprises.

What is Clop Ransomware?

Clop ransomware is a type of malware that encrypts files on a victim’s system, making them inaccessible until a ransom is paid to hackers. It’s popular for its double extortion strategy, which means that in addition to encrypting files, threat actors exfiltrate sensitive and confidential information from the target’s device or network. If the ransom is not paid, they threaten to publish the stolen data, which can lead to serious data breaches and reputational damage for businesses and individuals.

Clop ransomware is often distributed through phishing emails, malicious attachments, or by exploiting zero-day vulnerabilities in software. Once it infects a system, it searches for important files and encrypts them, demanding a ransom payment, usually in cryptocurrency, in exchange for a decryption key.

Common indicators of the Clop ransomware are encryption extensions, file hashes, and IP addresses. Bad actors rename the targeted files with either of the extensions- .clop or .CIop (capital i instead of small L). Also, the ransom notes are saved as ClopReadMe.txt or CIopReadMe.txt (capital i instead of small L).

How Does Clop Ransomware Work?

Clop proceeds strategically so that it stays undetected. Here’s how it unfolds-

1. Infection Vector

Clop ransomware begins by exfiltrating systems by sending phishing emails with infected downloadables or links, planting malware, installing exploit kits, etc. Another common tactic they use involves sending emails with malicious HTML attachments that take the victim to a macro-enabled document. This helps install the Get2 loader that further aids the download of infected tools and programs like SDBOT, FlawedAmmyy, and Cobalt Strike.

2. Initial Compromise

After gaining access, the ransomware executes payload, starting its evil operations on the compromised device or network. It’s likely to proceed laterally within the network to infect other systems and servers.

3. File Encryption

It utilizes a strong encryption algorithm to encrypt files on the victim’s system. This includes critical data like documents, images, databases, and other files that might be crucial to the victim. Doing so gives them control over their data and puts them under pressure to pay ransom quickly. 

4. File Renaming

Encrypted files are often renamed with a specific extension, such as “.clop,” making them easily identifiable as being encrypted by Clop.

5. Ransom Demand

Clop ransomware typically leaves a ransom note in each folder containing encrypted files. This note provides instructions for the victim on how to pay the ransom (usually in cryptocurrency) to obtain the decryption key.

6. Data Exfiltration and Double Extortion

In addition to encrypting files for ransom, they exfiltrate sensitive data and threaten the victim to leak the information if the ransom is not paid within the specified time frame. They may also intimidate victims that they will sell the stolen data to competitors or on the dark web, adding more pressure.

7. Persistence and Obfuscation

Clop ransomware may attempt to establish persistence in the system by creating backdoors or modifying system settings. It may also employ techniques to evade detection by antivirus software or security tools.

8. Ransom Negotiation

As mentioned above, hackers leave a ransom note, which is then also used as a means of communication (mainly through a TOR-based chat or email) so that victims can negotiate the ransom payment and receive instructions for decrypting the hostage data.

What to Do if You Already Fell Victim to a Clop Ransomware Attack?

If you come across the indicators of the clop ransomware, immediately isolate the infected systems and networks to prevent it from spreading and making the situation worse. Determine the extent of the attack. Identify which systems and data have been encrypted and whether any data has been exfiltrated. Document the findings, as you may need this information for insurance claims or law enforcement reports.

Dealing with all this can be complicated, so you may want to seek professional help. You would also have to report the attack to law enforcement agencies. They can provide support, work to prevent future attacks, and potentially track down the perpetrators.

We also advise you to preserve the evidence of exploitation for further investigation. This usually includes logs and ransom notes.

Most companies keep backups, and if you are one of those, then restore the data after cleaning your system so that there isn’t a possibility of re-infection. If hackers don’t go for double extortion, restoring the backups can be a lifesaver! 

Clop Ransomware Prevention Strategies

Considering the damage it can cause, it’s all the more important to establish some preventive practices in your organization to prevent clop ransomware and similar attacks-

  • Patched Software and Devices

Unpatched software and devices are easy to break into, and that’s why hackers love slipping into them. The vulnerabilities of such software and devices are well-documented, giving hackers an edge as they don’t have to discover new ways to break in. They just use what’s already known!

With the introduction of Cybercrime-as-a-Service or CaaS, many tools are available at cheaper rates that are known to exploit certain types of unpatched software. This is another good reason for hackers to target your un-updated systems. So don’t neglect any update notifications.   

You can’t possibly look after all the devices, systems, networks, files, emails, etc., to identify indicators of Clop ransomware. So, train your team members, irrespective of their department, to read the signs of invasions. Remember, in social engineering-based attacks, your employees are your first line of defense!

Schedule regular meetings to educate them on device security, software updates, and data protection. They should know how to report suspicious or potentially dangerous activity to the right person. Moreover, if your team runs remotely, train them on best practices for securing home networks and devices, such as using VPNs and secure Wi-Fi.

More than anything, encourage using password managers, setting strong, unique passwords, and not sharing or writing them down.

Network fragmentation is a cybersecurity strategy that involves dividing a network into smaller, isolated segments separated by security measures like firewalls. This approach helps protect against ransomware attacks by limiting the attack’s ability to spread across the entire network. 

If Clop ransomware infects one segment, network fragmentation can contain the damage and prevent it from reaching other parts of the network. Additionally, monitoring smaller network segments allows security teams to detect and respond to threats more effectively.

Email filters ascertain incoming emails with malicious downloadables, links, or ransomware payloads and block their entry. Newer versions of email filtering tools can analyze user behavior to pick up and report anomalies.

In sandboxing, potentially risky applications or codes are run in a controlled, isolated environment called a sandbox. A sandbox is completely separated from the main technical environment. It allows the safe execution and testing of potentially malicious codes.

This method also enables security teams to study the ransomware’s behavior and develop countermeasures. Using sandboxing, organizations can effectively identify and block ransomware threats before they cause damage.

As email is a prominent cyberattack and ransomware vector, it is essential to protect it. Our DMARC analyzer is a one-stop solution for your email security needs! Try it out by taking a free trial for your domain.

*** This is a Security Bloggers Network syndicated blog from PowerDMARC authored by Ahona Rudra. Read the original post at: https://powerdmarc.com/understanding-clop-ransomware/

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