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Researchers detailed BlueSky, an emerging Windows ransomware family that rapidly encrypts files through a multithreaded design and uses anti-analysis features plus a staged PowerShell infection chain. The malware was observed being delivered from kmsauto[.]us via start.ps1 and stage.ps1, then saved locally as javaw.exe. It attempts privilege escalation with JuicyPotato on older Windows systems and uses exploits for CVE-2020-0796 and CVE-2021-1732 on newer hosts before encrypting files, appending the .bluesky extension, and dropping ransom notes named # DECRYPT FILES BLUESKY #.txt and # DECRYPT FILES BLUESKY #.html.
Technical analysis found BlueSky shares strong code similarities with Conti v3, particularly in its multithreaded architecture and network share enumeration, while its cryptography aligns more closely with Babuk through the use of ChaCha20 for file encryption and Curve25519 for key generation. The ransomware excludes selected extensions and directories, creates host-specific identifiers, and stores encryption-state artifacts including a mutex and HKCU\Software\<32-byte ID> registry entries. Investigators also found RedLine-related samples hosted on the same domain, indicating possible infrastructure overlap or operational ties even though no direct code overlap was identified.
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Palo Alto Networks Unit 42 published an analysis of the BlueSky ransomware family, describing its multithreaded encryption, staged PowerShell delivery from kmsauto[.]us, privilege-escalation methods, and code similarities to Conti v3 and Babuk.
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Attackers brute-forced the `sa` account on an internet-facing Microsoft SQL Server and escalated a compromise into a full BlueSky ransomware deployment in about 32 minutes. After access was obtained, they enabled `xp_cmdshell`, launched PowerShell payloads, established a Cobalt Strike beacon, and used Tor2Mine tooling to disable antivirus, create persistence, and install an XMRig-based Monero miner. The intrusion then expanded through remote service creation and SMB activity toward domain controllers and file shares before the ransomware binary, masquerading as `vmware.exe`, was executed on the initial host. Files were encrypted with the `.bluesky` extension and a ransom note named `# DECRYPT FILES BLUESKY #.txt` was dropped, while investigators reported no evidence of data exfiltration. BlueSky is a Windows-focused ransomware family observed since 2022 that has been distributed through phishing emails, phishing sites, and trojanized downloads in addition to direct server compromise. Technical analysis shows the malware adjusts privileges, hides threads from debuggers, creates a mutex, and selectively skips some system-related files and directories while targeting user and database data. It accelerates encryption across local and network resources using multithreading and Windows I/O completion ports, stores recovery-related data in the Windows registry, terminates selected processes before encryption, appends the `.bluesky` extension to locked files, and generates ransom notes in both TXT and HTML formats.
Aug 14, 2026
Researchers found that **Rook** is a 64-bit Windows ransomware family built heavily from the leaked **Babuk** source code, reusing routines for service and process termination, shadow copy deletion, and core encryption logic while adding a more efficient multithreaded file-encryption model. The malware encrypts files with per-file AES keys protected by RSA-2048 through the **Mbed TLS** library, appends the `.Rook` or `.ROOK` extension, drops a ransom note named `HowToRestoreYourFiles.txt`, and targets local drives, mounted volumes, network resources, and operator-supplied paths. Analysts also observed Rook deleting volume shadow copies, attempting to stop backup, database, and security tools, storing victim key material in the Windows registry, hiding its executable in an NTFS alternate data stream named `:ask`, and deleting itself after execution without observed persistence. Threat intelligence linked Rook’s early operations to data-theft extortion claims, including a reported first victim in Kazakhstan’s financial sector, where the operators said they stole **1,123 GB** of data. Delivery has been associated mainly with third-party access frameworks such as **Cobalt Strike**, though phishing has also been reported, and samples have appeared packed with **UPX** or **VMProtect**. Separate reverse-engineering work concluded that **NightSky** is very likely a fork of Rook, sharing nearly identical key generation, threading, synchronization, encrypted file structure, and RSA/AES workflow, with the main cryptographic change being NightSky’s use of AES-128-CBC instead of Rook’s intermittent AES-128-ECB approach.
Aug 15, 2026
**BlackByte** emerged as a ransomware-as-a-service operation targeting Windows environments across critical infrastructure and other sectors, with victims reported in government facilities, finance, food and agriculture, and broad industry verticals worldwide. U.S. authorities said some intrusions began with exploitation of a Microsoft Exchange vulnerability, while other reporting tied initial access to phishing and **ProxyShell** activity. Once inside, BlackByte operators and affiliates used lateral movement, privilege escalation, scheduled tasks, remote execution, and data theft before encrypting systems and threatening publication on leak sites, with activity concentrated heavily in North America and Europe and notable interest in Latin American targets. Technical analyses show the group rapidly improved its malware after early versions exposed a major weakness: some samples fetched a disguised `forest.png` key file from hardcoded infrastructure and reused the same symmetric key across victims, enabling decryption in certain cases. Later BlackByte variants shifted from C# to **Go**, strengthened cryptography from earlier AES/RSA-based approaches to **Curve25519** and **ChaCha20**, and expanded capabilities including process and service termination, shadow-copy deletion, Defender exclusion changes, AMSI evasion, worm-like propagation through Active Directory and SMB, process injection, and so-called print bombing. Researchers and government agencies also documented use of tools such as **AnyDesk**, **WinRAR**, `certutil`, `vssadmin`, and network scanners, underscoring BlackByte’s progression into a more resilient and operationally mature extortion platform.
Aug 15, 2026