Storm-0558 Attacks: What You Need to Know

Storm-0558 Attacks: What You Need to Know

Storm-0558 is a threat actor or cyber-espionage group that has been associated with cyber-attacks. The group is known for conducting sophisticated and targeted campaigns with a focus on espionage, data theft, and credential access. 

The name “Storm-0558” is a designation given by cybersecurity researchers and experts to identify and track the activities of this specific threat actor.

In this comprehensive article, we will explore the Storm-0558 extortion group techniques, how the attack happens, and what to do if Storm-0558 compromises your systems or machines. Also, see how you can protect your business’s sensitive and critical data by taking simple preventive actions.

Storm-0558 attacks overview

Storm-0558 represents a persistent and technically adept threat actor engaged in state-sponsored cyber-espionage, widely attributed to the Chinese government. The group primarily targets US and European diplomatic, economic, and legislative bodies.

 It has been observed using forged authentication tokens to access user email from approximately 25 organizations, including government agencies and related consumer accounts in the public cloud. 

The goals of the Storm-0558 attacks include espionage, data theft, and credential access. The group aims to compromise email accounts belonging to high-profile individuals and organizations to gather sensitive information.

How to identify Storm-0558 

Indicators of compromise (IOCs) are pieces of forensic data that can help identify malicious activity or malware associated with a cyber attack. It includes the encryption extension, file hashes, and IP addresses, among other details cyber criminals leave as they infect a machine or system. 

But, if you can’t identify the threat strain through its IOCs, you can use Proven Data’s free ransomware ID tool to check if the Storm-0558 is the cyberthreat that encrypts your files.

Important: Some of these indicators require technical knowledge of the infected system, so you may need to contact your IT team or a digital forensics service provider.

Storm-0558 tactics, techniques, and procedures (TTPs)

Storm-0558 initiated its attack by obtaining an inactive Microsoft account (MSA) consumer signing key. This key, designed for consumer accounts, contained a validation error that the threat actor exploited for unauthorized Azure AD enterprise authentication. The exploitation of this flaw allowed Storm-0558 to forge authentication tokens, enabling the impersonation of Azure AD users.

With the forged authentication tokens, Storm-0558 gained unauthorized access to enterprise mail systems, including Outlook Web Access (OWA) and 

Using a seemingly legitimate client flow, Storm-0558 leveraged the forged tokens to gain access to the Outlook Web Access (OWA) API. Through this access, the threat actor retrieved legitimate access tokens for Exchange Online using the GetAccessTokenForResource API. Taking advantage of a design flaw in the API, Storm-0558 could obtain new access tokens by presenting previously issued ones.

Additionally, Storm-0558 employed a combination of PowerShell and Python scripts to perform REST API calls against the OWA Exchange Store service. These scripts facilitated the downloading of various email components, including emails, attachments, conversations, and information about email folders.

Following the initial compromise, Storm-0558’s post-compromise activities were narrowly focused on email access and exfiltration. Rather than engaging in widespread disruption or manipulation, the threat actor targeted and extracted information from compromised email accounts.

Threat actor infrastructure

Storm-0558 utilized dedicated infrastructure running the SoftEther proxy software. This strategic choice complicated detection and attribution, making it challenging to trace the actor’s activities back to their origin.

The threat actor further employed a series of dedicated infrastructure servers specifically for token replay and interaction with Microsoft services. These servers offered a more efficient means for Storm-0558 to carry out malicious activities, including the management of a web panel for authentication.

How to handle a Storm-0558 attack

It is important to note that handling a cyber attack can be complex and requires expertise. Therefore, it is recommended to seek professional help from a reputable data recovery service, such as Proven Data to help you recover your data and remove the ransomware from your system.

You can also report the attack to law enforcement agencies, such as the FBI, and cybersecurity organizations to help prevent future attacks and catch the perpetrators.

We strongly recommend contacting cybersecurity services to handle cyber attacks. Proven Data technicians not only retrieve ransomware-encrypted data but also create forensic reports and streamline incident response, minimizing your business downtime and financial loss.

Important: Do not pay the ransom. Paying the ransom does not guarantee that you will get your data back, and it may encourage the attackers to continue their criminal activities. Check our in-depth article on what happens if you pay the ransom.

How to prevent cyber attacks

Preventing Storm-0558 attacks is always the best cybersecurity tactic. If you are a recent victim, you must follow these tips to avoid a new cyber attack:

Keep your software up to date

Regularly update your operating system and programs to uphold security standards. Reputable OS providers will consistently check their software for vulnerabilities and patch up their security standards to protect against newly detected threats.

Use reputable antivirus software

Employ reputable antivirus software to significantly bolster protection against malware, and regularly check that it is updated. You can also check your network for vulnerabilities and learn where you need to improve your security system.

Be cautious of suspicious emails

Even though there are no known cases of Storm-0558 using phishing as an attack method, it’s important to exercise caution when dealing with emails from unfamiliar or dubious origins. Refrain from opening files or clicking on links within emails that you are not expecting or that seem suspicious.

Do not download cracked software

Cracked software is the term used to describe illicitly modified or pirated versions of commercial software, typically distributed without proper authorization or licensing. Cybercriminals frequently conceal their executables within cracked software distribution websites, leading users to unwittingly download and execute the malware.

Backup your data

Regularly back up your data to an external hard drive or cloud storage service to prevent complete data loss in case of a cyber attack. A highly recommended strategy for data loss prevention is the 3-2-1 backup strategy.

The 3-2-1 backup strategy involves creating three total copies of your data: two on different media and one offsite, ensuring redundancy and protection against data loss. And at least one copy offsite to prevent loss due to natural disasters or other local incidents.

The 3-2-1 backup strategy involves creating three total copies of your data: two on different media and one offsite, ensuring redundancy and protection against data loss. And at least one copy offsite to prevent loss due to natural disasters or other local incidents.

Educate yourself and your teams

Educate yourself and your employees about the risks of cyberattacks and how to avoid them, such as avoiding suspicious emails or downloads.

Consult cybersecurity professionals

Proven Data offers cyber security services to help you keep your data protected against threat actors. From vulnerability assessment to ensure your systems and servers do not have open doors for cyber attacks, to Incident Response (IR) services for immediate response in case of a successful attack.

We also have the option of managed detection and response (MDR) services that help organizations improve their security posture, minimize risk, and protect sensitive data and assets.

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