Report
Malware Spotlight: RansomHub Ransomware
Arete Analysis

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Executive Summary
In 2024, Arete’s Incident Response (IR) team responded to dozens of incidents attributed to the RansomHub threat actor group. Engagements attributed to RansomHub increased rapidly since Arete first observed them in May 2024, and the group quickly established itself as one of the top three threat actor groups since
July 2024.
RansomHub has impacted multiple sectors across Arete engagements, including professional services, public services, healthcare, high technology, financial services, and manufacturing. The group has targeted several high-profile targets since its emergence, including telecom giant Frontier and British auction house Christie’s. RansomHub also claimed to possess data stolen from Change Healthcare, which was the victim of an ALPHV/BlackCat ransomware attack in February 2024. RansomHub announced the sale of Change’s data after leaking some of the alleged data a day beforehand.
Advertisements for the RansomHub Ransomware-as-a-Service (RaaS) appeared on cybercriminal forums on February 2, 2024, highlighting an encryptor developed using the C++ and Go programming languages. The use of Go makes it easier for ransomware groups to target a wide variety of operating systems without needing to rewrite significant portions of the malware, as Go allows developers to compile executables for Windows, Linux, and macOS platforms from a single codebase. These advertisements were accompanied by
a new data leak site (DLS) under the RansomHub branding on the dark web.
RansomHub is suspected to be a re-brand of the “Knight” ransomware group, whose source code was listed for sale on the underground RAMP forum on February 18, 2024. From research, Arete can confirm various similarities between RansomHub and Knight’s encryptors.
This spotlight explores the ransomware group’s observed behavior, background information on the threat actor, and statistics from Incident Response engagements, along with a technical analysis of RansomHub’s ransomware executable. Finally, we discuss security recommendations to better defend against this evolving cyber threat and mitigate the risk of financial and reputational losses.
Incident Response Data on the RansomHub Ransomware Group
Background
RansomHub became a notable ransomware operation in 2024, and, alongside Akira, represented a verysignificant percentage of Arete Incident Response engagements in Q3 of 2024.

Source: Arete's Q3 2024 Crimeware Report
The group utilizes both Windows and Linux variants of encryptors, which increases its operational capability to target a wide range of victims of various sectors and sizes. RansomHub operates under a double extortion model, which involves exfiltrating sensitive data and encrypting the victims’ systems to coerce a payment for
a decryptor and data deletion.
Technical Analysis
Malware analysis revealed that RansomHub ransomware:
Supports multiple command-line arguments.
Requires a password to properly execute and encrypt files.
Encrypts files on the system and mounted shares.
Creates a ransom note with the following filename: .README_.txt
Self-identifies the group as RansomHub in the ransom note.
References a data leak site in the ransom note that, when accessed, self-identifies the group as RansomHub.
Kills a list of processes and services.
Maintains a list of whitelisted files and directories to make sure it will not render the system unusable, preventing recovery when running a decryptor.
Attempts to prevent system recovery by deleting the system’s volume shadow copies.
Clears the Windows event logs.
Creates a desktop wallpaper image in the “%temp%\” directory and later modifies a registry key to change desktop wallpaper.
Execution Pattern/Arguments
The RansomHub ransomware needs command line arguments to execute and encrypt files in the system.
Command line arguments supported:
Command line arguments | Description |
|---|---|
-cmd | CMD to be executed before encryption. |
-disable-net | Disable network before running. |
-fast value | Fast encryption mode. |
-file value | Only process file inside defined files. For example, -file C://1.txt, -file D://2.txt. |
-host value | Only process net share inside defined hosts. -host 10.10.10.10 -host 10.10.10.11. |
-only-local | Only encrypt local disks. |
-pass [SHA256 string] | Password needed to execute the ransomware. A 64-character string. |
-path value | Only process files inside defined paths. -path C:// -path D:// -path //10.10.10.10/d/ |
-safeboot | Reboot in Safe Mode before running. |
-safeboot-instance | Run as Safe Mode instance. |
-skip-vm value | Skip shutting down VMs. Example: -skip-vm “Ubuntu 22.04 LTS”, -skip-vm “Windows Server 2012”. |
-sleep [integer value] | Sleep for a period of time to run (minute). |
-verbose | Log to console. |
Ransomware execution with the command line argument –help:

Figure 1. Command line arguments supported by the ransomware
The ransomware will not execute in the system without the “-pass” argument followed by a SHA-256 value that is unique in each engagement. Execution of ransomware to encrypt files:
RansomHub.exe -pass [SHA-256] Example: 7ac8cd689f5d9f4c1ddca14ec84965ed42b17343ebe086076ba0e7a46a80f81f |
|---|
Once the SHA-256 password value is provided, the ransomware will decrypt a JSON based ransomware configuration at the run time.

Decrypted JSON field name and descriptions:
Name | Description |
|---|---|
master_public_key | Curve25519 public key used in the file encryption process. |
extension | Extension added to encrypted files. |
note_file_name | Ransom note file name, default value is .README<encrypted_file_extension>.txt |
note_full_text | Ransom note content. |
settings | Ransomware operation setting. |
credentials | Contains common or locally stolen credentials which are used for propagation and further infection. |
kill_services | Terminates list of services. |
kill_processes | Terminates list of processes. |
white_folders | Excludes listed directories. |
white_files | Excludes listed files. |
white_hosts | Excludes listed hosts. |
Stop Services and Processes
Before file encryption, the ransomware terminates a pre-determined list of processes and services to encrypt as many files as possible.
Process names:
“agntsvc.exe”, “dbeng50.exe”, “dbsnmp.exe”, “encsvc.exe”, “excel.exe”, “firefox.exe”, “infopath.exe”, “isqlplussvc.exe”, | ||
|---|---|---|
Services names:
“mepocs”, “memtas”, “veeam”, “svc$”, “backup”, “sql”, “vss”, “sql$”, “mysql”, “mysql$”, “sophos”, “MSExchange”, | ||
|---|---|---|
The ransomware also tries to list and stop VMs by executing the following PowerShell command.
powershell.exe -Command PowerShell -Command “{ Get-VM | Stop-VM -Force }” | ||
powershell.exe Get-VM | Stop-VM -Force -inputFormat xml -outputFormat text |
File and Directory Exclusions
The ransomware excludes system-related files and folders, ransomware-related files, and whitelisted extensions during encryption.
Excluded file and extensions:
“NTUSER.DAT”, “autorun.inf”, “boot.ini”, “desktop.ini”, “thumbs.db”, “*.deskthemepack”, “*.themepack”, “*.theme”, | ||
|---|---|---|
Excluded directories:
“*\\$windows.~ws*”, “*\\$windows.~bt*”, “*\\windows\\*”, “*\\windows.old*”, “*\\system volume information*”, | ||
|---|---|---|
Inhibit System Recovery
Windows operating systems contain features that can help fix corrupted system files, including shadow copies, which are backups of files created by the Volume Shadow Copy Service (VSS). By deleting shadow copies, the ransomware can prevent victims from restoring files from backups, making it more difficult for them to recover their data without paying the ransom.
The ransomware deletes volume shadow copies before file encryption by starting the following process:
powershell.exe -Command PowerShell -Command “\”Get-CimInstance Win32_ShadowCopy | Remove-CimInstance\”” | ||
|---|---|---|
System Network Connections Discovery
The ransomware can enumerate network-mounted shares by scanning the network interfaces.
Data Encrypted for Impact
The ransomware initially finds available drives, then loads the files one by one using the Windows API “FindFirstFileW“ and “FindNextFileW”. The ransomware generates random keys to encrypt the files, and after encrypting them, the keys are encrypted using a public key. To encrypt files, the ransomware uses a combination of a decrypted Curve 25519 public key and AES algorithms.
The default extension value is the first six characters of the Curve 25519 public key.

Figure 2. Extension added to the encrypted files
Files smaller than 0x100000 bytes are completely encrypted. If the file size is larger than 0x100000 bytes, the ransomware encrypts the file in 0x100000 bytes blocks and skips every 0x200000 bytes of data in between encrypted chunks.

Figure 3. 0x100000 bytes encrypted file.
Upon successful execution, the ransomware creates ransom notes with the file name “README_[encrypted_file_extension].txt”

Figure 4. RansomHub ransom note
Ransom note content:
We are the RansomHub. Your company Servers are locked and Data has been taken to our servers. This is serious. | ||
|---|---|---|
Modify Registry
The ransomware performs a registry key modification to change the desktop wallpaper.
Registry key change:
Registry key | Value name | Value data |
|---|---|---|
Computer\HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\ CurrentVersion\Explorer\Wallpapers | BackgroundHistory | C:\Users\%USERNAME%\ |
Screenshot showing the registry key modification:

Wallpaper image content from the
C:\Users\%USERNAME%\AppData\Local\Temp\MkgXoB.png file:

Mutex
The mutex is the fundamental tool for managing shared resources between multiple threads or processes. Typically, ransomware uses a mutex to avoid reinfecting the victim system and causing multiple layers of encryption. The ransomware did not create a mutex during execution.
Network Activity
The ransomware did not try to communicate with a remote server other than encrypting data from mounted shares.
Indicator Removal
The ransomware clears Windows Event Logs to hide its malicious activity. Windows Event Logs keep a record of a computer’s alerts and notifications. The ransomware runs the following commands to clear the logs:
cmd.exe /c wevtutil cl security | ||
|---|---|---|
File and Directory Permissions Modification
The ransomware uses the fsutil tool to redirect file system access to a different location after gaining access to a compromised network. The ransomware uses the following command line to redirect file system access, enabling remote to remote and remote to local symbolic links:
fsutil behavior set SymlinkEvaluation R2L:1 | ||
|---|---|---|
Indicators of Compromise
Indicator | Type | Context |
|---|---|---|
de7913504efe4584bdd9dd1ec13c4de4152a84df5e1cb-c31d0dd8fe70c88b5e0 | SHA256 hash | RansomHub ransomware |
README_<encrypted_file_extension>.txt | File name | RansomHub ransom note |
powershell.exe -Command PowerShell -Command “{ Get-VM | Stop-VM -Force }” | Process | Retrieve information about VMs and forces a shutdown |
powershell.exe -Command PowerShell -Command ” | Process | Volume Shadow Copy deletion |
cmd.exe /c wevtutil cl security | Process | Clearing Windows Event Logs |
cmd.exe /c “\\”fsutil behavior set SymlinkEvaluation R2L:1\\”” | Process | Enable remote to remote and remote to local symbolic links |
Key: Computer\HKEY_CURRENT_USER\SOFTWARE\Microsoft\ | Registry | Desktop wallpaper modification |
ransomxifxwc5eteopdobynonjctkxxvap77yqifu2emfbecgbqdw6qd[.] | URL | TA data leak site (DLS) |
Ransomware Configuration
RansomHub decrypted configuration information extracted:
Data Leak Site
The RansomHub ransom note contains a data leak site (DLS) that displayed the following page, self-identifying the group as RansomHub:

Figure 5. TOR DLS
Similarities with Other Ransomware
During our analysis, we observed some similarities between RansomHub, ALPHV/BlackCat, and Knight ransomware executables.
The following table highlights some of the similarities:
Malware Family | Common Arguments | Password | JSON Configuration |
|---|---|---|---|
RansomHub | pass | SHA256 strings value | extension |
ALPHV/BlackCat | –access-token (similar to -pass in RansomHub and Knight) | SHA256 strings value | extension |
Knight | pass | SHA256 strings value | extension |
Detection Mechanisms
Custom Detections and Blocking with Arete Bloktd℠
Note: These threat hunting queries may need to be tuned for your specific network environment. | ||
|---|---|---|
Yara
rule RansomHub_ransomware_executable meta: author = “areteir.com” strings: $s1 = “json:\”local_disks\”” condition: ((uint16(0) == 0x5A4D) and (uint32(uint32(0x3C)) == 0x00004550)) and } | ||
|---|---|---|
Recommended Mitigations
Organizations can find the full list of US government-recommended ransomware prevention and mitigation guidance here: https://www.cisa.gov/stopransomware/ransomware-guide
Arete provides data-driven cybersecurity solutions to transform your response to emerging cyber threats.
References
At Arete, we envision a world without cyber extortion, where people, businesses, and governments can thrive. We are taking all that we know from over 9,000 engagements to inform our solutions and strengthen powerful tools to better prevent, detect, and respond to the cyber extortion threats of tomorrow. Our elite team of experts provides unparalleled capabilities to address the entire cyber threat lifecycle, from incident response and restoration to advisory and managed security services. To learn more about our solutions, visit www.areteir.com.
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Current: Misconfigured Server Reveals Multiple Phishing Campaigns
Researchers uncovered three Microsoft 365 phishing campaigns after discovering a misconfigured HTTP server that exposed a threat actor’s phishing tools, configurations, victim logs, and operational infrastructure. The investigation revealed two operators using custom Evilginx-based adversary-in-the-middle (AiTM) phishing frameworks to steal authentication sessions and bypass MFA protections. A third operator abused Microsoft’s OAuth Device Code flow by tricking victims into completing authentication through Microsoft’s legitimate login process, allowing attackers to obtain valid access and refresh tokens without stealing passwords. The largest campaign compromised at least 218 victims across 12 countries, primarily targeting corporate Microsoft 365 accounts, with refresh tokens enabling persistent access. Researchers also identified the use of remote management tools for maintaining access, AI-assisted development of phishing tooling, and links to broader Phishing-as-a-Service (PhaaS) ecosystems, highlighting how commodity frameworks and automation are lowering the barrier for sophisticated identity-based attacks.
What’s Notable and Unique
The campaigns demonstrate the continued shift from traditional credential theft to identity- and token-based compromise, in which attackers target authentication sessions, cookies, and OAuth tokens rather than relying solely on password theft. By obtaining valid authentication artifacts, attackers can access Microsoft 365 environments while bypassing conventional MFA protections.
The use of Evilginx-based AiTM frameworks highlights how publicly available phishing tools have evolved into effective MFA-bypass platforms. These frameworks proxy legitimate login pages, capture authenticated sessions, and allow attackers to reuse valid sessions without requiring victims’ credentials again.
The OAuth Device Code flow abuse represents a different attack method, in which attackers leverage a legitimate Microsoft authentication mechanism to obtain tokens after victims approve the request. This approach bypasses password theft entirely by abusing trusted authentication workflows.
The exposed infrastructure provided insight into attacker operations, including phishing configurations, victim tracking data, remote administration tools, and evidence of AI-assisted development. The findings demonstrate how phishing ecosystems now provide reusable tooling and automation that reduce the technical expertise required to conduct large-scale identity attacks.
Analyst Comments
These Microsoft 365 phishing campaigns demonstrate the ongoing evolution of identity-focused attacks, as adversaries increasingly target authentication sessions, tokens, and legitimate cloud authorization mechanisms to bypass traditional security controls. The combination of AiTM phishing, OAuth abuse, remote management tools, and PhaaS infrastructure enables threat actors to maintain persistent access while blending into legitimate cloud activity.
The growing availability of phishing frameworks and AI-assisted attack development highlights the need for continuous identity security improvements beyond traditional phishing defenses. Arete recommends that organizations strengthen identity monitoring, adopt phishing-resistant MFA where possible, review OAuth application permissions, monitor token activity, and implement conditional access policies to detect and restrict suspicious Microsoft 365 authentication behavior. Security teams should also monitor post-compromise indicators such as abnormal mailbox access, suspicious application consent, unauthorized remote tools, and unusual sign-in activity.
Sources
One Misconfigured Server, Three Active Campaigns: Full exposure of three AiTM Phishing Operators
Misconfigured Server Reveals Three Evilginx Phishing Operations Targeting Microsoft 365
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Helix threat actors reportedly initiate intrusions through vishing campaigns, impersonating trusted individuals—often the target's manager—and leveraging caller ID spoofing to enhance credibility.
The actors then attempt to persuade victims to complete device code phishing workflows, enabling unauthorized access to corporate accounts and Microsoft 365 resources.
Following successful authentication, the actors conduct reconnaissance and enumeration of SharePoint environments before identifying and exfiltrating sensitive data for extortion purposes.
Helix's variable dwell times suggest a flexible, target-specific operational approach, enabling the group to adapt its intrusion timeline to victim environments to maximize data theft and extortion opportunities while minimizing the likelihood of detection. Helix's operations also appear to be focused on large-scale data theft and extortion, with an emphasis on automated SharePoint data exfiltration following successful credential or session compromise.
Overlaps with Other Extortion Groups
Researchers assess that Helix likely emerged from or has operational overlap with the ShinyHunters and BlackFile/Redact cybercriminal ecosystems. ShinyHunters historically focuses on compromising websites, developer repositories, and exposed credentials or API keys to gain access to corporate cloud environments, monetizing stolen victim data on the dark web. BlackFile utilizes identity-centric and social engineering–driven methods of intrusion, relying less on traditional malware and instead leveraging credential theft, privilege escalation, rapid data exfiltration, and coercive tactics such as swatting to maximize extortion pressure. In May 2026, BlackFile announced that it would be rebranding as “Redact” (which may have later rebranded again to “Pink”), yet despite the rebrands, threat actors operating within these groups continued to exhibit similar operational models, victimology, and extortion methodologies.
Analyst Comments
Collectively, the similarities between the groups suggest the possibility of a shared criminal ecosystem, affiliate network, or loosely connected threat cluster rather than entirely independent operations. The emergence of Helix further reflects the broader trend of extortion groups rebranding or fragmenting while retaining proven attack techniques and operational infrastructure to support their criminal activities. Despite suspicion of these groups’ connectivity, the exact nature of the relationship remains unconfirmed. As Helix focuses on identity-based attack techniques to gain access to Microsoft 365 environments, Arete recommends that organizations remain vigilant in using MFA, enforcing strong identity security controls, continuously monitoring authentication activity, and enhancing user awareness of social engineering tactics.
Sources
Helix, a New Name in the Data Extortion Ecosystem?
BlackFile actively extorting data-theft victims in retail and hospitality sector
"Pink" Data Extortion Group Hunting With Evasive Phishing Kits
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What’s Notable and Unique
Researchers identified a shared operator actively managing negotiation panels for both the INC and Lynx ransomware groups, providing rare operational evidence linking the two RaaS operations beyond infrastructure or malware similarities.
Analysis of the exposed infrastructure revealed a structured ransomware operation with dedicated roles for access acquisition, victim management, negotiations, and technical support, reflecting an organized ransomware-as-a-service (RaaS) model rather than an ad hoc criminal group.
The operation reportedly integrates artificial intelligence into multiple stages of the attack lifecycle, including vulnerability research, penetration testing, attack automation, and ransomware development, demonstrating the increasing adoption of AI to enhance offensive capabilities.
Mitigations
Organizations should assume that exposed or previously compromised FortiGate credentials may be leveraged for ransomware deployment and immediately reset administrative and VPN credentials while enforcing multi-factor authentication (MFA) for all privileged access. Security teams should ensure that FortiGate appliances are fully patched, restrict management interfaces to trusted networks, and audit administrative accounts and firewall configurations for unauthorized changes. Organizations should also monitor for anomalous authentication activity, hunt for published indicators of compromise (IOCs), and review VPN and firewall logs for signs of unauthorized access. Maintaining centralized logging and a well-practiced incident response process can help detect and contain attacks before they progress to lateral movement or ransomware deployment.
Analyst Comments
The attribution of FortiBleed to the INC and Lynx ransomware operations reinforces the growing convergence between credential-harvesting campaigns and ransomware deployment, highlighting the role of initial access operations in modern RaaS ecosystems. The relationship between INC and Lynx also aligns with Arete's previous research, which identified a shared malware lineage. INC Ransom, first observed in 2023, was later leaked or sold, enabling code reuse by other threat actors. Lynx, which emerged in 2024, is widely regarded as an evolution of the INC codebase. Sinobi ransomware, identified in 2025, shares near-identical binaries and infrastructure, and approximately 99% code similarity with Lynx. Further details on the code correlation between INC, Lynx, and Sinobi are available in Arete's 2025 Annual Report.
Sources
Is FortiBleed Linked to INC and Lynx Ransomware?
FortiBleed credential-theft campaign linked to Lynx ransomware
FortiBleed Unmasked: A Joint Operation by Lynx and INC Ransomware Groups
FortiBleed Credential Theft Campaign Attributed to INC and Lynx Ransomware Groups



