In a flash alert released on Monday, the Federal Bureau of Investigation (FBI) shared indicators of compromise, tactics, techniques, and procedures (TTP), and mitigation measures about a threat actor dubbed OnePercent Ransomware Group that has been targeting US organizations since November 2020.
The agency revealed that
OnePercent Group actors compromise victims through a phishing email in which an attachment is opened by the user. The attachment’s macros infect the system with the IcedID1 banking trojan. IcedID downloads additional software to include Cobalt Strike. Cobalt Strike moves laterally in the network, primarily with PowerShell remoting.
As explained by BleepingComputer, OnePercent encrypts files using a random eight-character extension (e.g., dZCqciA) and will add uniquely named ransom notes linking to the gang’s .onion website. After that, the ransomware group gains access to their victims’ networks and exfiltrates their data before deploying the ransomware payloads.
For more information on the demanded ransom, negotiate with the attackers, and get “technical support”, victims can use the Tor website. In most cases, they will be asked to pay the ransom in bitcoins, and a decryption key will be provided up to 48 hours after the payment is made.
Image Source: FBI
Additionally, the ransomware gang will also reach out to their victims using spoofed phone numbers, threatening to leak the stolen data unless they’re connected with a company negotiator.
If the victim does not pay the ransom quickly, the OnePercent Group actors threaten to release a portion of the stolen data to various clearnet websites. If the ransom is not paid in full after the “one percent leak”, OnePercent Group actors threaten to sell the stolen data to the Sodinokibi Group.
The OnePercent Group operators use a wide variety of applications and services including:
- AWS S3 cloud
- IcedID
- Cobalt Strike
- Powershell
- Rclone
- Mimikatz
- SharpKatz
- BetterSafetyKatz
- SharpSploit
Although the FBI hasn’t revealed any information on OnePercent Group’s past attacks, the agency linked the ransomware affiliate to the REvil (Sodinokibi) ransomware gang, whose data leak site they’ve used to leak and auction their victims’ stolen files.
Image Source: FBI
The agency recommends affected organizations apply the following mitigations:
- Back-up critical data offline.
- Ensure administrators are not using “Admin Approval” mode.
- Implement Microsoft LAPS.
- Ensure copies of critical data are in the cloud or on an external hard drive or storage device.
- Secure your back-ups and ensure data is not accessible for modification or deletion from the system where the original data resides.
- Keep computers, devices, and applications patched and up-to-date.
- Consider adding an email banner to emails received from outside your organization.
- Disable unused remote access/Remote Desktop Protocol (RDP) ports and monitor remote access/RDP logs.
- Audit user accounts with administrative privileges and configure access controls with least privilege in mind.
- Implement network segmentation.
- Use multi-factor authentication with strong passphrases.