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Port 5900 Details


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Port(s) Protocol Service Details Source
5900 tcp vnc VNC (Virtual Network Computing) - remote control programs. VNC typically also uses ports 5800+ and 5900+ for additional machines.

Citrix NetScaler appliance Lights out Management uses ports 4001, 5900, 623 TCP to run a daemon that offers unified configuration management of routing protocols.

Backdoor.Evivinc [Symantec-2004-042518-0520-99] also uses this port.

Some Apple applications use this port as well: Apple Remote Desktop 2.0 or later (Observe/Control feature), Screen Sharing (Mac OS X 10.5 or later)

RealVNC 4.0 and earlier allows remote attackers to cause a denial of service (crash) via a large number of connections to port 5900.
References: [CVE-2004-1750], [BID-11048]

W32.Gangbot [Symantec-2007-012219-2952-99] (2007.01.22) - a worm that opens a back door and connects to an IRC server. It spreads by searching for vulnerable SQL servers and by sending an HTML link to available contacts on instant messenger programs. It also spreads by exploiting the Microsoft Internet Explorer Vector Markup Language Buffer Overflow Vulnerability [BID-20096] and RealVNC Remote Authentication Bypass Vulnerability [BID-17978].

Vino 2.28, 2.32, 3.4.2, and earlier allows remote attackers to read clipboard activity by listening on TCP port 5900.
References: [CVE-2012-4429]

Vino could allow a remote attacker to bypass security restrictions, caused by an error in vino-preferences dialog box when providing information on network accessibility. By sending a specially-crafted UPnP request to TCP port 5900, an attacker could exploit this vulnerability to bypass security restrictions to scan internal hosts or proxy Internet traffic and gain unauthorized access to the vulnerable application.
References: [XFDB-82881], [CVE-2011-1164]

EchoVNC Viewer is vulnerable to a denial of service, caused by an error when allocating heap buffer size. By connecting to a malicious server, a remote attacker could exploit this vulnerability using a malformed request to TCP port 5900 to cause the application to crash.
References: [BID-61545], [XFDB-86113]

A vulnerability has been identified in RAPIDLab 1200 systems / RAPIDPoint 400 systems / RAPIDPoint 500 systems (All versions_without_ use of Siemens Healthineers Informatics products), RAPIDLab 1200 Series (All versions < V3.3 _with_ Siemens Healthineers Informatics products), RAPIDPoint 500 systems (All versions >= V3.0 _with_ Siemens Healthineers Informatics products), RAPIDPoint 500 systems (V2.4.X_with_ Siemens Healthineers Informatics products), RAPIDPoint 500 systems (All versions =< V2.3 _with_ Siemens Healthineers Informatics products), RAPIDPoint 400 systems (All versions _with_ Siemens Healthineers Informatics products). A factory account with hardcoded password might allow attackers access to the device over port 5900/tcp. Successful exploitation requires no user interaction or privileges and impacts the confidentiality, integrity, and availability of the affected device. At the time of advisory publication, no public exploitation of this security vulnerability is known. Siemens Healthineers confirms the security vulnerability and provides mitigations to resolve the security issue.
References: [CVE-2018-4846]

Siemens SINUMERIK Controllers could allow a remote attacker to execute arbitrary code on the system, caused by an integer overflow. By sending specially crafted network requests to TCP Port 5900, an attacker could exploit this vulnerability to execute arbitrary code on the system with elevated privileges.
References: [CVE-2018-11458], [XFDB-154197], [BID-106185]

Remote Framebuffer (TCP/UDP) [RFC6143] (IANA official)
SG
5900 tcp,udp Virtual Network Computing (VNC) remote desktop protocol (used by Apple Remote Desktop and others) (official) Wikipedia
5900 tcp vnc Virtual Network Computer SANS
3283,5900,5988 tcp applications Apple Remote Desktop Portforward
5900 tcp,udp applications OSXvnc Portforward
5900 tcp,udp applications RealVNC Portforward
5900 tcp applications Teamviewer Portforward
5800,5500,5900 tcp applications Tight VNC Portforward
5500,5800,5900 tcp applications Vitual Network Computing Portforward
5500,5800,5900 tcp applications VNC Portforward
5900 tcp vnc Virtual Network Computer display 0 Nmap
5900 tcp threat Evivinc Bekkoame
5900 tcp threat VNC Bekkoame
5900 tcp,udp rfb Remote Framebuffer [RFC6143] , registered 2006-03 IANA
14 records found
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Related ports: 5280  5500  5800  5901  5902  5903  

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External Resources
SANS Internet Storm Center: port 5900

Notes:
Port numbers in computer networking represent communication endpoints. Ports are unsigned 16-bit integers (0-65535) that identify a specific process, or network service. IANA is responsible for internet protocol resources, including the registration of commonly used port numbers for well-known internet services.
Well Known Ports: 0 through 1023.
Registered Ports: 1024 through 49151.
Dynamic/Private : 49152 through 65535.

TCP ports use the Transmission Control Protocol, the most commonly used protocol on the Internet and any TCP/IP network. TCP enables two hosts to establish a connection and exchange streams of data. TCP guarantees delivery of data and that packets will be delivered in the same order in which they were sent. Guaranteed communication/delivery is the key difference between TCP and UDP.

UDP ports use the Datagram Protocol. Like TCP, UDP is used in combination with IP (the Internet Protocol) and facilitates the transmission of datagrams from one computer to applications on another computer, but unlike TCP, UDP is connectionless and does not guarantee reliable communication; it's up to the application that received the message to process any errors and verify correct delivery. UDP is often used with time-sensitive applications, such as audio/video streaming and realtime gaming, where dropping some packets is preferable to waiting for delayed data.

When troubleshooting unknown open ports, it is useful to find exactly what services/processes are listening to them. This can be accomplished in both Windows command prompt and Linux variants using the "netstat -aon" command. We also recommend runnig multiple anti-virus/anti-malware scans to rule out the possibility of active malicious software. For more detailed and personalized help please use our forums.

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