Bl00dy Ransomware

Original Issue Date:- June 12, 2023

Virus Type:-Ransomware

Severity:- Medium

It has been reported that a ransomware known as "Bl00dy" is targeting organizations. The ransomware is majorly focussing on education sector. The attackers evade user authentication measures and gain unauthorized entry to the organization's server by assuming the role of administrators.

Infection Mechanism

The victims’ organizations are targeted by ransomware where the vulnerable PaperCut servers are exposed to the internet with CVE-2023-27350. As a result, data is leaked and the victims' systems are encrypted.

The Bl00dy ransomware attackers utilized the PaperCut vulnerability on port 9191 to initiate an initial network connection. The threat actors exploit the PaperCut NG vulnerability, specifically targeting port 9191, which led to the exposure of compromised organization information.

Once the threat actors gain access to the victim's systems, they proceed to steal data and encrypt the targeted systems. The attackers gain remote access to the devices by spawning new processes of 'cmd.exe' and 'powershell.exe' with elevated privileges. This allowed them to use the compromised devices as launch points for spreading laterally across the network.

The vulnerability also paves the way to deploy additional malicious payload for eg. Cobalt strike beacon to the compromised systems.

After infiltrating the victims' systems, the malicious actors modify the encrypted files by adding the ".DRTTY" extension. Additionally, a ransom note is placed in encrypted folders. The ransomware also eliminates shadow copies, further complicating the recovery process.

Bl00dy Gang Ransom Note [Source: CISA]

The ransom note mention about instructions for exchanging the decryption key, as well as information about the stolen data and communication and negotiation links. The Threat actors also utilize TOR to communicate with C2.

Indicator of Compromise:

Email:

decrypt.support@privyonline[dot]com
fimaribahundqf@gmx[dot]com

Domains:

anydeskupdate[dot]com
anydeskupdates[dot]com

Tox ID:

E3213A199CDA7618AC22486EFECBD9F8E049AC36094D56AC1BFBE67EB9C3CF2352CAE9EBD35F

IP address:

102.130.112[dot]157
172.106.112[dot]46

For more detailed list of IoC, kindly refer the URL:

https://www.cisa.gov/news-events/cybersecurity-advisories/aa23-131a

Best Practices and Recommendations:

Update PaperCut to the most recent version. If an immediate patch is not possible, take the following precautions to safeguard vulnerable PaperCut servers from internet access:

Option 1: Implement external controls by blocking all inbound traffic from external IP addresses to the web management portal (port 9191 and 9192 by default).
Option 2: Implement both internal and external controls by blocking all inbound traffic to the web management portal. Please note that after implementing this step, remote management of the server will not be possible.

Maintain offline backups of data, and regularly maintain backup and restoration. This practice will ensure the organization will not be severely interrupted, have irretrievable data.

Ensure all backup data is encrypted, immutable (i.e., cannot be altered or deleted) and covers the entire organization’s data infrastructure.

Implement all accounts with password logins (e.g., service account, admin accounts, and domain admin accounts) to have strong, unique passwords.

Implement multi-factor authentication for all services to the extent possible, particularly for webmail, virtual private networks, and accounts that access critical systems.

Remove unnecessary access to administrative shares.

Use a host-based firewall to only allow connections to administrative shares via server message block (SMB) from a limited set of administrator machines.

Enable protected files in the Windows Operating System to prevent unauthorized changes to critical files.

Disable remote Desktop Connections, employ least-privileged accounts. Limit users who can log in using Remote Desktop, set an account lockout policy. Ensure proper RDP logging and configuration.

Check regularly for the integrity of the information stored in the databases.

Ensure integrity of the codes /scripts being used in database, authentication and sensitive system.

Establish Domain-based Message Authentication, Reporting, and Conformance (DMARC), Domain Keys Identified Mail (DKIM) and Sender Policy Framework (SPF) for your domain, which is an email validation system designed to prevent spam by detecting email spoofing by which most of the ransomware samples successfully reaches the corporate email boxes.

Keep the operating system, third party applications (MS office, browsers, browser Plugins) up-to-date with the latest patches.

Application white listing/Strict implementation of Software Restriction Policies (SRP) to block binaries running from %APPDATA% and %TEMP% paths. Ransomware sample drops and executes generally from these locations.

Maintain updated Antivirus software on all systems.

Don't open attachments in unsolicited e-mails, even if they come from people in your contact list, and never click on a URL contained in an unsolicited e-mail, even if the link seems benign. In cases of genuine URLs close out the e-mail and go to the organization's website directly through browser.

Follow safe practices when browsing the web. Ensure the web browsers are secured enough with appropriate content controls.

Network segmentation and segregation into security zones - help protect sensitive information and critical services. Separate administrative network from business processes with physical controls and Virtual Local Area Networks.

Disable ActiveX content in Microsoft Office applications such as Word, Excel, etc.

Restrict access using firewalls and allow only to selected remote endpoints, VPN may also be used with dedicated pool for RDP access.

Use strong authentication protocol, such as Network Level Authentication (NLA) in Windows.

Additional Security measures that may be considered are:

Use RDP Gateways for better management.
Change the listening port for Remote Desktop.
Tunnel Remote Desktop connections through IPSec or SSH.
Two-factor authentication may also be considered for highly critical systems.

If not required consider disabling PowerShell / windows script hosting.

Restrict users' abilities (permissions) to install and run unwanted software applications.

Enable personal firewalls on workstations.

Implement strict External Device (USB drive) usage policy.

Employ data-at-rest and data-in-transit encryption.

Consider installing Enhanced Mitigation Experience Toolkit, or similar host-level anti-exploitation tools.

Block the attachments of file types, exe|pif|tmp|url|vb|vbe|scr|reg|cer|pst|cmd|com|bat|dll|dat|hlp|hta|js|wsf

Carry out vulnerability Assessment and Penetration Testing (VAPT) and information security audit of critical networks/systems, especially database servers from CERT-IN empanelled auditors. Repeat audits at regular intervals.

Individuals or organizations are not encouraged to pay the ransom, as this does not guarantee files will be released. Report such instances of fraud to CERT-In and Law Enforcement agencies.

References: