BlueSky Ransomware: Fast Encryption via Multithreading

BlueSky Ransomware: Fast Encryption via Multithreading

BlueSky ransomware is an emerging family that has adopted modern techniques to evade security defenses.

Ransomware is a malicious program designed to encrypt a user’s data and demand a ransom for the decryption. BlueSky ransomware predominantly targets Windows hosts and utilizes multithreading to encrypt files on the host for faster encryption.

In our analysis, we found code fingerprints from samples of BlueSky ransomware that can be connected to the Conti ransomware group. In particular, the multithreaded architecture of BlueSky bears code similarities with Conti v3, and the network search module is an exact replica of it.

However, in another respect, BlueSky more closely resembles Babuk Ransomware. Both use ChaCha20, an algorithm for file encryption, along with Curve25519 for key generation.

According to research done by CloudSEK, PowerShell scripting is used to drop and download BlueSky ransomware from a fake website to encrypt data. After successful encryption, BlueSky Ransomware renames the encrypted files with the file extension .bluesky and drops a ransom note file named # DECRYPT FILES BLUESKY #.txt and # DECRYPT FILES BLUESKY #.html.

Palo Alto Networks customers receive protections from BlueSky ransomware and other types of ransomware through Cortex XDR, the Next-Generation Firewall and cloud-delivered security services including WildFire. The Advanced URL Filtering subscription provides real-time URL analysis and malware prevention for BlueSky ransomware.

If you think you may have been impacted by a cyber incident, the Unit 42 Incident Response team is available 24/7/365. You can also take preventative steps by requesting any of our cyber risk management services.

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