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Conti Ransomware: In-Depth Technical Breakdown

Conti Ransomware In-Depth Technical Breakdown

Conti ransomware has earned notoriety, notably for its involvement in the Costa Rican government hack. Operating as a ransomware-as-a-service (RaaS) group, Conti specializes in infiltrating networks, encrypting crucial data, and extorting exorbitant sums of money. In 2023 alone, researchers attribute millions of dollars in losses to Conti’s malicious activities. Consequently, system administrators responsible for safeguarding enterprise systems must be well-versed in the workings of Conti ransomware.

In this blog, we explore of Conti ransomware, delving into its infiltration techniques, data encryption methods, lateral movement strategies, and crucial mitigation measures that system administrators can implement to stop potential Conti ransomware attacks.

History and Evolution of Conti Ransomware

A.     Origins and Emergence

Conti ransomware first emerged onto the cyber threat landscape in mid-2020, quickly gaining notoriety for its sophisticated tactics and destructive capabilities. Believed to be the successor of the Ryuk ransomware strain, Conti represents a new generation of ransomware-as-a-service (RaaS) operations. Its origins can be traced back to the dark web forums where cybercriminals convene to exchange knowledge, tools, and services.

As a RaaS group, Conti operates on a profit-sharing model, providing its ransomware tools to affiliates who carry out the actual attacks. This decentralized structure has enabled Conti to rapidly expand its reach and execute attacks on a global scale.

B.     Notable Campaigns and Targets

Conti ransomware has left a trail of destruction in its wake, targeting organizations across various sectors, including healthcare, finance, government, and critical infrastructure. One of the most high-profile incidents involving Conti occurred in November 2022 when the Costa Rican government fell victim to a devastating ransomware attack. The attack crippled critical government systems, leading to widespread disruptions in public services and raising concerns about national security.

Other notable targets of Conti ransomware include large corporations, educational institutions, and municipalities, highlighting the indiscriminate nature of its attacks.

C.     Evolution of Tactics and Techniques

Since its inception, Conti ransomware has continuously evolved its tactics and techniques to evade detection and maximize its impact. Initially, Conti relied heavily on phishing emails and exploit kits to gain initial access to target networks. However, as security defenses have improved, Conti has adapted by incorporating more sophisticated methods such as exploiting vulnerabilities in remote desktop protocols (RDP) and leveraging supply chain attacks to infiltrate networks.

Furthermore, Conti has refined its encryption algorithms and ransomware delivery mechanisms to ensure that victims’ data remains inaccessible until a ransom is paid.

Additionally, Conti has been known to employ data exfiltration tactics, threatening to leak sensitive information if victims refuse to pay the ransom, further increasing the pressure on affected organizations.

How Conti Ransomware Attacks Work

A.     Infection Vectors of Conti Ransomware

Exploit Kits:

Conti ransomware commonly exploits vulnerabilities in software and operating systems to gain initial access to target systems. It leverages exploit kits, such as Rig and Fallout, which are toolkits used by cybercriminals to automate the process of exploiting known vulnerabilities in software applications. These exploit kits are often delivered through malicious websites or compromised legitimate websites, which unsuspecting users may visit. Once a victim’s system is compromised, Conti is deployed to carry out its ransomware activities.

Phishing Emails:

Another prevalent infection vector utilized by Conti ransomware is phishing emails. These emails are crafted to appear legitimate and contain malicious attachments or links. Upon opening the attachment or clicking the link, unsuspecting users inadvertently download and execute the Conti ransomware payload.

Phishing emails masquerade as invoices, shipping notifications, or urgent messages from seemingly reputable sources, enticing recipients to take action that leads to infection.

Remote Desktop Protocol (RDP) Compromise:

Conti ransomware operators also exploit insecure Remote Desktop Protocol (RDP) configurations to gain unauthorized access to target networks. They use brute force attacks or stolen credentials to compromise RDP endpoints, allowing them to infiltrate network systems. Once inside the network, Conti propagates laterally to other systems and executes its ransomware payload.

B.     Encryption Mechanisms of Conti Ransomware

Encryption Algorithms Used:

Conti ransomware employs strong encryption algorithms, such as RSA and AES, to encrypt files on compromised systems. These algorithms ensure that encrypted data remains inaccessible without the corresponding decryption key, which is held by the ransomware operators.

  • RSA is used for asymmetric encryption, where a unique public key is used to encrypt data, and a private key, held by the attackers, is required for decryption.
  • AES is used for symmetric encryption, where the same key is used for both encryption and decryption.

File Types Targeted:

Conti ransomware targets a wide range of file types commonly found on enterprise systems, including documents, spreadsheets, databases, images, videos, and archives. By encrypting these critical files, Conti aims to disrupt business operations and coerce victims into paying the ransom to regain access to their data.

Persistence Mechanisms:

To ensure persistence on compromised systems, Conti ransomware employs various techniques, such as creating registry keys, scheduled tasks, or autostart entries. These mechanisms allow Conti to maintain its presence on the infected system even after reboots or attempts to remove the ransomware.

C.     Conti Ransomware Command and Control (C2) Infrastructure

Communication Protocols:

Conti ransomware communicates with its command and control (C2) infrastructure using encrypted channels to receive commands from the attackers and transmit stolen data or ransom payment instructions.

Common communication protocols used by Conti include HTTP(S), DNS, and Tor hidden services, which provide anonymity and resilience to takedown attempts by law enforcement or security researchers.

Domain Generation Algorithms (DGAs):

To evade detection and takedown efforts, Conti ransomware uses domain generation algorithms (DGAs) to dynamically generate a large number of pseudo-random domain names. These domain names are used as rendezvous points for communication between infected systems and the attackers’ C2 servers.

By constantly changing the domain names associated with its C2 infrastructure, Conti makes it more difficult for defenders to block or sinkhole communication channels.

D.     How Conti Ransomware Evades Detection

Anti-Analysis Measures:

Conti ransomware employs various anti-analysis techniques to evade detection and analysis by security researchers and antivirus software. These techniques include code obfuscation, packing, and the use of anti-debugging or anti-VM (virtual machine) techniques.

By making it challenging to analyze the ransomware code, Conti aims to delay detection and prolong its dwell time on compromised systems.

Sandbox Evasion:

Conti ransomware is designed to detect and evade analysis environments, such as sandbox environments used by security researchers to analyze malware samples in a controlled environment. It may employ techniques to detect virtualized or emulated environments and alter its behavior accordingly to evade detection or analysis.

Anti-Forensic Techniques:

In addition to evading analysis, Conti ransomware incorporates anti-forensic techniques to hinder efforts to recover encrypted data or trace the attackers’ activities. These techniques may include securely wiping deleted files, tampering with system logs, or encrypting critical system files needed for forensic analysis.

By making it difficult to trace the ransomware operators’ activities, Conti aims to maintain anonymity and evade law enforcement efforts.

What Happens in a Conti Ransomware Attack

A.     Initial Compromise:

The lifecycle of a Conti ransomware attack typically begins with the initial compromise of a target system. This initial compromise often occurs through various infection vectors, such as exploit kits, phishing emails, or compromised remote desktop protocol (RDP) endpoints.

Once the ransomware payload is executed on the victim’s system, Conti establishes a foothold within the network and begins its malicious activities.

B.     Reconnaissance and Lateral Movement:

With a foothold established, Conti ransomware conducts reconnaissance to identify valuable assets within the compromised network. This may involve scanning network shares, enumerating user accounts, and mapping out network topology. Armed with this information, Conti proceeds to move laterally across the network, exploiting vulnerabilities and weak security controls to escalate privileges and gain access to additional systems.

C.     Data Encryption and Ransom Note Deployment:

Once Conti has gained access to critical systems and data, it initiates the encryption process to render files inaccessible to the victim. Conti employs strong encryption algorithms, such as RSA and AES, to encrypt files on both local and networked drives. Simultaneously, Conti deploys ransom notes across compromised systems, informing victims of the encryption and providing instructions on how to pay the ransom to obtain the decryption key.

D.     Extortion and Communication with Victims:

Following the encryption of data and deployment of ransom notes, Conti ransomware operators initiate communication with the victim organization to extort payment. This communication may occur via email, instant messaging, or through Tor-based communication channels to maintain anonymity. Conti operators threaten to leak sensitive data or increase the ransom amount if victims fail to comply with their demands, adding pressure to pay the ransom.

E.     Potential Exfiltration of Data:

In addition to encrypting files, Conti ransomware also exfiltrate sensitive data from compromised systems before initiating the encryption process. This data exfiltration serves as leverage for the attackers, providing them with additional leverage to extort payment from victims. Conti operators threaten to publicly release or sell stolen data if victims refuse to pay the ransom, further incentivizing compliance.

F.      Ransom Payment Process:

If victims choose to pay the ransom, Conti ransomware operators provide instructions on how to make payment, typically in cryptocurrency such as Bitcoin. Once payment is received, the attackers provide the decryption key to unlock the encrypted files, allowing victims to regain access to their data. However, there is no guarantee that paying the ransom will result in the successful recovery of files, and victims may still experience data loss or other negative consequences as a result of the attack.

What is the Impact of Conti Ransomware on Businesses

A.     Financial Losses:

Conti ransomware attacks often result in significant financial losses for victim organizations. These losses stem from various factors, including the payment of ransom demands, costs associated with remediation and recovery efforts, and potential revenue losses due to operational disruptions. The ransom demands issued by Conti operators can range from thousands to millions of dollars, depending on the size and nature of the targeted organization.

Additionally, organizations may incur expenses related to forensic investigations, legal fees, and investments in cybersecurity measures to prevent future attacks.

Furthermore, the long-term financial impact of reputational damage and loss of customer trust can further exacerbate the financial toll of Conti ransomware attacks.

G.    B. Operational Disruptions:

Conti ransomware attacks can cause significant operational disruptions for victim organizations, disrupting business-critical processes and systems. The encryption of data and systems by Conti ransomware can render essential services and applications inaccessible, leading to downtime and productivity losses.

Moreover, organizations may experience delays in service delivery, supply chain disruptions, and interruptions to customer-facing operations, resulting in financial and reputational repercussions. The time and resources required to restore systems and recover data further prolong the operational impact of Conti ransomware attacks, worsening the disruption to normal business operations.

B.     Reputational Damage:

The fallout from Conti ransomware attacks can have far-reaching implications for the reputation and brand image of victim organizations. News of a ransomware attack can erode customer trust and confidence in the organization’s ability to protect sensitive data and maintain operational resilience. The perception of negligence or incompetence in protecting customer information negatively impacts the organization’s reputation and leads to loss of business opportunities.

Moreover, public disclosure of a ransomware incident attracts negative media attention, further increasing reputational damage and undermining stakeholder trust. Rebuilding trust and repairing reputational harm following a Conti ransomware attack is a challenging and time-consuming process for affected organizations.

C.     Regulatory Implications:

Conti ransomware attacks may trigger regulatory scrutiny and legal obligations for victim organizations, particularly in industries subject to stringent data protection and privacy regulations. Depending on the nature of the data compromised in the attack, organizations may be required to report the incident to regulatory authorities and affected individuals within specified timeframes. Failure to comply with regulatory requirements leads to hefty fines, legal penalties, and reputational damage for non-compliance.

Moreover, organizations may be subject to civil lawsuits and class-action litigation from affected individuals seeking damages for the exposure or loss of personal information. The regulatory fallout from Conti ransomware attacks underscores the importance of implementing robust cybersecurity measures and compliance frameworks to mitigate legal and financial risks.

The impact of Conti ransomware attacks extends beyond financial losses and operational disruptions, encompassing reputational damage and regulatory implications that can have lasting consequences for victim organizations.

How to Recover Data Post Conti Ransomware Attack

In March 2022, a Ukrainian security researcher leaked the source code from the Conti ransomware operation to protest the gang’s position on the Russia-Ukraine conflict. Kaseperky’s security team used this source code to release a decryptor called “RakniDecryptor”, available on their website.

Here’s a brief step-by-step guide on how to use the RakhniDecryptor tool:

  • Download from the official Kaspersky website and extract the files from it.
  • Open the folder containing the extracted files.
  • Run the RakhniDecryptor.exe executable file.
  • Carefully read the License Agreement presented by the tool, and click Accept if you agree to all its terms.
  • Click the “Change parameters” link to configure the decryption process.
  • Select the objects you want to scan for encrypted files. You can choose to scan hard drives, removable drives, and network drives.
  • Check the box labeled “Delete crypted files after decryption” if you want the tool to remove copies of encrypted files with extensions such as LOCKED, KRAKEN, DARKNESS, etc., after decryption.
  • Click OK to confirm your selections and return to the main interface.
  • Click “Start scan” to begin the scanning process.
  • Once the scanning is complete, select the encrypted file that you want to decrypt and click Open.
  • Read the warning message that appears and click OK to proceed with the decryption process.
  • The tool will decrypt the selected file, and the decrypted files will be saved in their original location.

It’s important to note that files with the CRYPT extension might be encrypted multiple times. In such cases, the RakhniDecryptor tool will decrypt the first layer of encryption and append the “.layerDecryptedKLR” suffix to the filename. You will need to repeat the decryption process for these files until they are fully decrypted.

Note: It is important to recognize that while RakhniDecryptor provides a valuable tool for decrypting Conti ransomware-encrypted files, it may not offer a swift resolution in all cases. Particularly, decryption of files with the CRYPT extension can be time-consuming, potentially taking up to 120 days on systems with modest processing power like an Intel Core i5-2400 processor.

In situations where decryption timeframes are extended, although data loss is averted, the significant downtime poses a substantial challenge unless the infrastructure can allocate ample processing and compute resources. Therefore, it is crucial to have robust contingency measures in place. Establishing ransomware-proof air-gapped and immutable backup solutions is paramount. These backups ensure quicker recovery times and effectively prevent data loss, protecting against the debilitating impacts of ransomware attacks on business continuity.

Case Studies of Conti Ransomware Attacks

A.     Notable Conti Ransomware Attacks

Exagrid Breach:

In June 2021, ExaGrid, a leading backup appliance supplier, was targeted by Conti ransomware operators, resulting in a high-stakes negotiation and a ransom payment of $2.6 million. The attack compromised ExaGrid’s internal systems, encrypting critical data and disrupting its operations. Despite ExaGrid’s emphasis on its strengths against ransomware, the incident exposed vulnerabilities within its network infrastructure.

Negotiations with the attackers, who had infiltrated ExaGrid’s network for over a month, involved escalating demands and intricate discussions, illustrating the sophistication of Conti ransomware operations.

Costa Rican Government Intrusion:

On April 11, 2022, Conti ransomware operatives initiated a five-day intrusion into the Costa Rican government’s network, resulting in the exfiltration of 672GB of sensitive data. The attack, marked by extensive reconnaissance and network traversal, targeted the Ministry of Finance’s systems, exploiting compromised VPN credentials to gain initial access. Conti operators employed advanced techniques, including Cobalt Strike beacon sessions and Mimikatz post-exploitation tools, to escalate privileges and move laterally across interconnected networks.

The ransomware attack culminated in the deployment of ransomware, prompting Costa Rica to declare a national emergency. Despite the unsophisticated nature of the attack, Conti’s impact reverberated across multiple government agencies, underscoring the need for robust cybersecurity defenses and incident response strategies.

ProxyShell Exploitation:

Recently, the Conti ransomware gang has been exploiting vulnerabilities in Microsoft Exchange servers, leveraging the ProxyShell exploit to breach corporate networks and deploy ransomware payloads. ProxyShell comprises three chained Microsoft Exchange vulnerabilities (CVE-2021-34473, CVE-2021-34523, CVE-2021-31207), enabling unauthenticated, remote code execution on vulnerable servers.

Although Microsoft patched these vulnerabilities in May 2021, technical details about their exploitation were recently disclosed, allowing threat actors to exploit them in attacks. Conti ransomware operators utilize ProxyShell to drop webshells, backdoors, and deploy ransomware payloads, as observed in recent incidents. In a notable case investigated by Sophos, Conti affiliates compromised an organization’s network within 48 hours using ProxyShell, exfiltrating 1TB of data and deploying ransomware to encrypt devices. The incident underscores the critical importance of promptly patching Exchange servers and implementing robust cybersecurity measures to mitigate the risk of ProxyShell exploitation and Conti ransomware attacks.

B.     Lessons Learned from Real-World Incidents

These case studies provide valuable insights into the evolving threat landscape of Conti ransomware attacks and offer crucial lessons for organizations to enhance their cybersecurity resilience:

  • The Exagrid breach highlights the importance of proactive cybersecurity measures and robust incident response capabilities. Organizations must prioritize the implementation of defense-in-depth strategies, including air-gapped and immutable backup solutions, to mitigate the risk of ransomware attacks and ensure rapid recovery from data encryption.
  • The Costa Rican government intrusion underscores the significance of continuous monitoring, threat detection, and response mechanisms to detect and thwart ransomware attacks in their early stages. Effective cybersecurity hygiene, such as regular vulnerability assessments and patch management, is essential for preventing initial access and minimizing the impact of ransomware incidents.
  • The exploitation of ProxyShell vulnerabilities by Conti ransomware underscores the evolving tactics and techniques employed by threat actors to infiltrate corporate networks and deploy ransomware payloads. Prompt patching of Exchange servers and proactive threat hunting are critical to mitigating the risk of ProxyShell exploitation and Conti ransomware attacks.

Mitigation Strategies for Conti Ransomware

A. Prevention Measures

Patch Management:

One of the most critical steps in preventing Conti ransomware attacks is ensuring timely patch management. Regularly updating software, especially operating systems and applications like Microsoft Exchange servers, helps mitigate vulnerabilities that threat actors may exploit.

Organizations must prioritize the installation of security patches released by vendors to address known vulnerabilities and strengthen their defense posture against ransomware threats.

Email Filtering:

Email remains one of the primary attack vectors for ransomware distribution. Implementing robust email filtering solutions can help organizations block malicious attachments, links, and phishing emails used by Conti ransomware operators to initiate attacks. By filtering out suspicious email content and preventing users from interacting with malicious payloads, organizations can significantly reduce the risk of ransomware infections via email-based attacks.

Endpoint Protection:

Deploying advanced endpoint protection solutions is essential for detecting and blocking ransomware threats targeting endpoints within the organization’s network. Endpoint protection platforms leverage techniques such as behavioral analysis, machine learning, and signature-based detection to identify and mitigate ransomware activity in real-time. By securing endpoints across the network, organizations can thwart Conti ransomware attacks and prevent the unauthorized encryption of critical data.

Air-Gapped and Immutable Backups:

One of the most effective mitigation strategies against Conti ransomware attacks is the implementation of air-gapped and immutable backups.

Air-gapped backups are stored offline and physically, or logically, isolated from the production environment, ensuring that ransomware cannot access or encrypt backup data.

Immutable backups, protected from modification or deletion, provide an additional layer of defense against ransomware tampering.

In the event of a ransomware attack, organizations can rely on air-gapped and immutable backups to restore systems and recover data without paying ransom demands.

B. Detection and Response

Intrusion Detection Systems:

Deploying intrusion detection systems (IDS) enables organizations to detect and respond to suspicious network activities indicative of ransomware attacks. IDS solutions monitor network traffic, analyze patterns, and identify anomalous behavior associated with ransomware activity. By promptly detecting and alerting security teams to potential ransomware incidents, IDS solutions play a crucial role in facilitating rapid incident response and containment efforts.

Endpoint Detection and Response:

Endpoint detection and response (EDR) solutions offer granular visibility into endpoint activities and help organizations detect and respond to ransomware threats across their network. EDR platforms monitor endpoint behavior, detect unauthorized file modifications, and facilitate threat hunting and incident response workflows. By leveraging EDR capabilities, organizations can quickly identify and mitigate Conti ransomware attacks, minimizing the impact on their systems and data.


Conti ransomware poses a significant and evolving threat to organizations worldwide, leveraging sophisticated tactics and techniques to infiltrate networks, encrypt data, and extort ransom payments. As evidenced by real-world case studies, such as the Exagrid breach, Costa Rican government intrusion, and exploitation of ProxyShell vulnerabilities, Conti ransomware operators continue to target entities across various sectors with devastating consequences.

To effectively mitigate the risk of Conti ransomware attacks, organizations must adopt a multi-layered approach to cybersecurity, encompassing prevention, detection, and response strategies. Prevention measures, including robust patch management, email filtering, endpoint protection, and the implementation of air-gapped and immutable backups, are crucial for thwarting ransomware threats before they can cause harm.

Furthermore, investments in detection and response capabilities, such as intrusion detection systems and endpoint detection and response solutions, are essential for early threat detection and rapid incident response. By leveraging advanced ransomware protection and data security technologies and implementing proactive mitigation strategies, organizations can strengthen their resilience against Conti ransomware attacks and safeguard their critical assets, operations, and reputation from cyber threats in an increasingly hostile digital landscape.

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