Adversaries may use [Valid Accounts](https://attack.mitre.org/techniques/T1078) to remotely control machines using Virtual Network Computing (VNC).  VNC is a platform-independent desktop sharing system that uses the RFB (“remote framebuffer”) protocol to enable users to remotely control another computer’s display by relaying the screen, mouse, and keyboard inputs over the network.(Citation: The Remote Framebuffer Protocol)

VNC differs from [Remote Desktop Protocol](https://attack.mitre.org/techniques/T1021/001) as VNC is screen-sharing software rather than resource-sharing software. By default, VNC uses the system's authentication, but it can be configured to use credentials specific to VNC.(Citation: MacOS VNC software for Remote Desktop)(Citation: VNC Authentication)

Adversaries may abuse VNC to perform malicious actions as the logged-on user such as opening documents, downloading files, and running arbitrary commands. An adversary could use VNC to remotely control and monitor a system to collect data and information to pivot to other systems within the network. Specific VNC libraries/implementations have also been susceptible to brute force attacks and memory usage exploitation.(Citation: Hijacking VNC)(Citation: macOS root VNC login without authentication)(Citation: VNC Vulnerabilities)(Citation: Offensive Security VNC Authentication Check)(Citation: Attacking VNC Servers PentestLab)(Citation: Havana authentication bug)
VNC
source_name: mitre-attack  url: https://attack.mitre.org/techniques/T1021/005  external_id: T1021.005     source_name: The Remote Framebuffer Protocol  description: T. Richardson, J. Levine, RealVNC Ltd.. (2011, March). The Remote Framebuffer Protocol. Retrieved September 20, 2021.  url: https://datatracker.ietf.org/doc/html/rfc6143#section-7.2.2     source_name: MacOS VNC software for Remote Desktop  description: Apple Support. (n.d.). Set up a computer running VNC software for Remote Desktop. Retrieved August 18, 2021.  url: https://support.apple.com/guide/remote-desktop/set-up-a-computer-running-vnc-software-apdbed09830/mac     source_name: VNC Authentication  description: Tegan. (2019, August 15). Setting up System Authentication. Retrieved September 20, 2021.  url: https://help.realvnc.com/hc/en-us/articles/360002250097-Setting-up-System-Authentication     source_name: Hijacking VNC  description: Z3RO. (2019, March 10). Day 70: Hijacking VNC (Enum, Brute, Access and Crack). Retrieved September 20, 2021.  url: https://int0x33.medium.com/day-70-hijacking-vnc-enum-brute-access-and-crack-d3d18a4601cc     source_name: macOS root VNC login without authentication  description: Nick Miles. (2017, November 30). Detecting macOS High Sierra root account without authentication. Retrieved September 20, 2021.  url: https://www.tenable.com/blog/detecting-macos-high-sierra-root-account-without-authentication     source_name: VNC Vulnerabilities  description: Sergiu Gatlan. (2019, November 22). Dozens of VNC Vulnerabilities Found in Linux, Windows Solutions. Retrieved September 20, 2021.  url: https://www.bleepingcomputer.com/news/security/dozens-of-vnc-vulnerabilities-found-in-linux-windows-solutions/     source_name: Offensive Security VNC Authentication Check  description: Offensive Security. (n.d.). VNC Authentication. Retrieved October 6, 2021.  url: https://www.offensive-security.com/metasploit-unleashed/vnc-authentication/     source_name: Attacking VNC Servers PentestLab  description: Administrator, Penetration Testing Lab. (2012, October 30). Attacking VNC Servers. Retrieved October 6, 2021.  url: https://pentestlab.blog/2012/10/30/attacking-vnc-servers/     source_name: Havana authentication bug  description: Jay Pipes. (2013, December 23). Security Breach! Tenant A is seeing the VNC Consoles of Tenant B!. Retrieved October 6, 2021.  url: http://lists.openstack.org/pipermail/openstack/2013-December/004138.html     source_name: Apple Unified Log Analysis Remote Login and Screen Sharing  description: Sarah Edwards. (2020, April 30). Analysis of Apple Unified Logs: Quarantine Edition [Entry 6] – Working From Home? Remote Logins. Retrieved August 19, 2021.  url: https://sarah-edwards-xzkc.squarespace.com/blog/2020/4/30/analysis-of-apple-unified-logs-quarantine-edition-entry-6-working-from-home-remote-logins     source_name: Gnome Remote Desktop grd-settings  description: Pascal Nowack. (n.d.). Retrieved September 21, 2021.  url: https://gitlab.gnome.org/GNOME/gnome-remote-desktop/-/blob/9aa9181e/src/grd-settings.c#L207     source_name: Gnome Remote Desktop gschema  description: Pascal Nowack. (n.d.). Retrieved September 21, 2021.  url: https://gitlab.gnome.org/GNOME/gnome-remote-desktop/-/blob/9aa9181e/src/org.gnome.desktop.remote-desktop.gschema.xml.in     