Dark web intelligence firm Cyble reports seeing an increase in cyberattacks targeting virtual network computing (VNC).
The VNC graphical desktop-sharing system relies on the Remote Frame Buffer (RFB) protocol to provide control of a remote machine over a network.
Exposing VNC to the internet has long been deemed a security risk, yet Cyble has identified over 8,000 internet-accessible VNC instances that have authentication disabled.
Cyble also warns of a spike in attacks targeting port 5900, the default port for VNC, noting that the Netherlands, Russia, and Ukraine have emerged as the top attacking countries.
Most of the exposed VNC instances, the threat intelligence firm says, are located in five countries: China, Sweden, the United States, Spain, and Brazil.
Some of the exposed VNCs belong to organizations in critical infrastructure sectors, including water treatment plants, manufacturers, and research facilities. Cyble says it was able to identify multiple human-machine interface (HMI) systems, SCADA systems, and workstations that are connected via VNC and internet-accessible.
Attackers able to compromise such systems may tamper with predefined settings, shut down industrial control systems (ICS), disrupt the supply chain and processes in the affected industries, or access sensitive data that can be used to further compromise ICS systems.
Exposing VNCs to the internet, Cyble notes, increases the likelihood of a cyberattack, including ransomware, data theft, and cyberespionage, all of which are typically preceded by an initial network compromise.
“Our investigation found that selling, buying, and distributing exposed assets connected via VNCs are frequently on cybercrime forums and markets,” Cyble notes.
While remote access to IT/OT infrastructure assets can prove handy, improperly implemented security measures could lead to highly impactful incidents and significant losses. Internet-exposed VNCs that lack authentication make it easy for attackers to access a victim’s network and create havoc.
“Readers should bear in mind that exposed VNCs from critical organizations put the national security, economy, energy, and transportation sectors at high risk of cyberattacks. It is advised that organizations using VNC and similar products should ensure that their ports and services are not exposed online and are appropriately secured,” Cyble concludes.
Related: Many Internet-Exposed Servers Affected by Exploited Redis Vulnerability
Related: Tool Links Internet-Exposed ICS to Google Street View
Related: 1,000 Organizations Exposed to Remote Attacks by FileWave MDM Vulnerabilities

More from Ionut Arghire
- Blackpoint Raises $190 Million to Help MSPs Combat Cyber Threats
- ‘Asylum Ambuscade’ Group Hit Thousands in Cybercrime, Espionage Campaigns
- Google Cloud Now Offering $1 Million Cryptomining Protection
- Pharmaceutical Giant Eisai Takes Systems Offline Following Ransomware Attack
- North Korean Hackers Blamed for $35 Million Atomic Wallet Crypto Theft
- Cisco Patches Critical Vulnerability in Enterprise Collaboration Solutions
- Android’s June 2023 Security Update Patches Exploited Arm GPU Vulnerability
- US, Israel Provide Guidance on Securing Remote Access Software
Latest News
- In Other News: AI Regulation, Layoffs, US Aerospace Attacks, Post-Quantum Encryption
- Blackpoint Raises $190 Million to Help MSPs Combat Cyber Threats
- Google Introduces SAIF, a Framework for Secure AI Development and Use
- ‘Asylum Ambuscade’ Group Hit Thousands in Cybercrime, Espionage Campaigns
- Evidence Suggests Ransomware Group Knew About MOVEit Zero-Day Since 2021
- SaaS Ransomware Attack Hit Sharepoint Online Without Using a Compromised Endpoint
- Google Cloud Now Offering $1 Million Cryptomining Protection
- Democrats and Republicans Are Skeptical of US Spying Practices, an AP-NORC Poll Finds
