HolleXD Ransomware: Analysis, Detection, and Recovery

The digital world is incessantly facing threats from various forms of cyberattacks, with ransomware being one of the most pernicious. The emergence of HelloXD ransomware in November 2021 marked a new chapter in the ever-evolving threat landscape.

This malware not only encrypts victims’ data but also employs double extortion tactics, making it a formidable threat to both Windows and Linux systems. At the heart of HelloXD’s operations is a threat actor known by the alias x4k, who has been linked to a slew of malicious activities.

What is HelloXD Ransomware?

Ransomware is a type of malware that encrypts files on a victim’s computer, demanding payment for the decryption key. HelloXD ransomware distinguishes itself with its unique approach to coercion. Unlike many other ransomware types, HelloXD lacks a dedicated leak site. Instead, it uses TOX chat for communication and negotiations with its victims, indicating a more personalized extortion strategy.

The Evolution of HelloXD Ransomware

Since its initial detection, HelloXD has undergone continuous development. The ransom notes have varied between samples, suggesting active and ongoing refinement by the authors. Notably, researchers from Unit 42 at Palo Alto Networks have uncovered a resemblance between HelloXD’s code and the leaked source code of the Babuk/Babyk ransomware, hinting at the possibility of shared origin or inspiration.

Technical Analysis of HelloXD

Malware Overview

HelloXD’s visual signature includes a modified ClamAV logo, a tactic likely designed to confuse and mislead. Upon execution, the ransomware attempts to cripple the system’s defenses by disabling shadow copies, a feature that could otherwise be used to restore encrypted files. The malware then proceeds to encrypt files, appending a “.hello” extension to signal its presence unequivocally.

Packer Analyses

Two distinct packers have been identified in the wild: a modified version of the open-source packer UPX and a more complex two-layer packer. The latter includes a custom UPX packer as its second layer, demonstrating the malware authors’ efforts to evade detection and analysis.

Ransomware Internals

HelloXD samples exhibit varying levels of obfuscation, with some employing minimal efforts and others utilizing more sophisticated control flow obfuscation. The ransomware leverages encryption algorithms such as Curve25519-Donna and Rabbit Cipher to secure its hold on the victim’s files. Furthermore, the inclusion of a secondary payload, MicroBackdoor, reveals an intent to monitor the ransomware’s progress and maintain access to the compromised systems.

The x4k Threat Actor

The individual or group behind HelloXD, known as x4k, has a history of selling exploits and hosting malware, indicating a well-entrenched position in the cybercriminal ecosystem. A unique string, “:wtfbbq” in UTF-16LE, found within HelloXD samples, has been linked to x4k’s infrastructure. This string is commonly associated with a self-deletion technique for executables, as seen in GitHub repositories like OffensiveNim.

Attack Methodology

HelloXD ransomware can spread through local networks, encrypting new files as it propagates. The most common infection vectors include malicious email attachments, Trojans, unreliable download sources, fake software updates, and software cracking tools. Notably, the HelloXD ransomware has been updated to include MicroBackdoor, facilitating easier navigation and data exfiltration from the infected system, as reported by PCrisk.

Measures to Counter HelloXD Ransomware

Detection and Prevention

To combat HelloXD, cybersecurity firms like Palo Alto Networks have developed tools such as Cortex XDR and Next-Generation Firewalls, which are designed to detect and prevent such threats. Additionally, their WildFire service aids in identifying new threats by analyzing unknown samples.

Removal and Recovery

If infected with HelloXD ransomware, it is crucial to remove the malware promptly to prevent further encryption. Legitimate antivirus software, such as Combo Cleaner for macOS, is recommended for this task. Recovery of files can be achieved through backups or by utilizing free or third-party decryption tools. However, paying the ransom is discouraged as it does not guarantee file recovery and further incentivizes criminal activity.

Best Practices for Protection

To safeguard against ransomware like HelloXD, individuals and organizations should adhere to best practices. These include refraining from opening files from suspicious emails, using official sources for downloads and updates, and employing reputable antivirus or anti-spyware software.

Reporting and Responding to an Infection

In the event of a HelloXD ransomware infection, it is advisable to report the incident to the relevant authorities, such as those listed on the No More Ransom Project. Isolating the infected device is a critical first step, followed by identifying the ransomware strain, which can be done through services like ID Ransomware. Searching for decryption tools and utilizing data recovery tools like Recuva can also aid in restoring files. Lastly, creating robust data backups is an essential preventative measure.

Indicators of Compromise (IOCs)

To assist in the detection and response to HelloXD ransomware attacks, cybersecurity experts provide Indicators of Compromise (IOCs). These IOCs include specific file hashes, IP addresses, and domain names associated with the ransomware and its infrastructure. For instance, the presence of files with the “.hello” extension or communication with known x4k command and control servers can signal an active infection. Unit 42 has compiled a comprehensive list of IOCs related to HelloXD ransomware and x4k’s activities, which can be invaluable for security teams in identifying breaches.

Understanding and Mitigating the Impact

The impact of a ransomware attack can be far-reaching, affecting not just the encrypted data but also undermining the trust in an organization’s ability to safeguard sensitive information. Understanding the technical workings of HelloXD ransomware and the tactics employed by the x4k threat actor is crucial for developing effective mitigation strategies. Organizations should conduct regular security training for employees, implement strict access controls, and maintain up-to-date security patches to minimize the risk of a successful ransomware attack.

Collaboration and Information Sharing

Combatting threats like HelloXD ransomware requires a collaborative approach. Sharing information about threats, vulnerabilities, and attacks can help the cybersecurity community stay ahead of cybercriminals. Platforms such as the Cyber Threat Alliance facilitate this exchange of information, allowing members to learn from each other’s experiences and enhance their defensive measures.

Legal and Ethical Considerations

Victims of ransomware attacks often face a dilemma: to pay or not to pay the ransom. While law enforcement agencies generally advise against paying, as it funds and encourages more criminal activity, the decision can be complex when critical data is at stake. Companies must weigh the legal and ethical implications, considering the potential for data loss, the cost of downtime, and the impact on stakeholders.

Future Outlook and Preparedness

As threat actors like x4k continue to evolve their tactics, the cybersecurity community must remain vigilant and proactive. Investing in advanced threat detection systems, establishing robust incident response plans, and fostering a culture of cybersecurity awareness are all essential steps in preparing for future threats. Additionally, leveraging resources such as the 2022 Unit 42 Ransomware Threat Report Highlights can provide valuable insights into emerging trends and threat actor behaviors.


HelloXD ransomware represents a significant threat in the cybersecurity landscape, characterized by its unique extortion methods and the incorporation of secondary payloads like MicroBackdoor. Behind this malicious software is the x4k threat actor, whose activities span a broad spectrum of cybercrime. By understanding the nature of this ransomware, employing best practices for prevention and response, and fostering collaboration within the cybersecurity community, organizations can better protect themselves against such threats.

The fight against ransomware is ongoing, and it requires a concerted effort from individuals, businesses, and governments alike. Staying informed, vigilant, and prepared is the best defense against the sophisticated and evolving tactics of cybercriminals like those behind HelloXD ransomware.