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Port 53 Details

known port assignments and vulnerabilities
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Port(s) Protocol Service Details Source
53 tcp,udp DNS DNS (Domain Name Service) used for domain name resolution. There are some attacks that target vulnerabilities within DNS servers.

Cisco Webex Teams services uses these ports:
443,444,5004 TCP
53, 123, 5004, 33434-33598 UDP (SIP calls)

Xbox 360 (Live) ports: 3074 TCP/UDP, 53 TCP/UDP, 80 TCP, 88 UDP
Xbox One (Live) ports: 3074 TCP/UDP, 53 TCP/UDP, 80 TCP, 88 UDP, 500 UDP, 3544 UDP, 4500 UDP

Apple MacDNS, FaceTime also use this port.

Some trojans also use this port: ADM worm, Bonk (DoS) trojan, li0n, MscanWorm, MuSka52, Trojan.Esteems.C [Symantec-2005-051212-1727-99] (2005.05.12), W32.Spybot.ABDO [Symantec-2005-121014-3510-99] (2005.12.10).

W32.Dasher.B [Symantec-2005-121610-5037-99] (2005.12.16) - a worm that exploits the MS Distributed Transaction Coordinator Remote exploit (MS Security Bulletin [MS05-051]).
Listens for remote commands on port 53/tcp. Connects to an FTP server on port 21211/tcp. Scans for systems vulnerable to the [MS05-051] exploit on port 1025/tcp.

Kerio Personal Firewall (KPF) 2.1.4 has a default rule to accept incoming packets from DNS (UDP port 53), which allows remote attackers to bypass the firewall filters via packets with a source port of 53.
References: [CVE-2003-1491] [BID-7436]

Stack-based buffer overflow in the dns_decode_reverse_name function in dns_decode.c in dproxy-nexgen allows remote attackers to execute arbitrary code by sending a crafted packet to port 53/udp, a different issue than [CVE-2007-1465].
References: [CVE-2007-1866] [SECUNIA-24688]

Siemens Gigaset SE461 WiMAX router 1.5-BL024.9.6401, and possibly other versions, allows remote attackers to cause a denial of service (device restart and loss of configuration) by connecting to TCP port 53, then closing the connection.
References: [CVE-2009-1152] [BID-34220]

Cisco IOS is vulnerable to a denial of service, caused by an error in NAT of DNS. By sending specially-crafted DNS packets to TCP port 53, a remote attacker could exploit this vulnerability to cause the device to reload.
References: [CVE-2013-5479], [XFDB-87455]

haneWIN DNS Server is vulnerable to a denial of service attack. A remote attacker could send a large amount of data to port 53 and cause the server to crash.
References: [XFDB-90583], [BID-65024], [EDB-31014]

named in ISC BIND 9.x (before 9.9.7-P2 and 9.10.x before 9.10.2.-P3) allows remote attackers to cause denial of service (DoS) via TKEY queries. A constructed packet can use this vulnerability to trigger a REQUIRE assertion failure, causing the BIND daemon to exit. Both recursive and authoritative servers are vulnerable. The exploit occurs early in the packet handling, before checks enforcing ACLs or configuration options that limit/deny service.
See: [CVE-2015-5477]

Tftpd32 is vulnerable to a denial of service, caused by an error when processing requests. If the DNS server is enabled, a remote attacker could send a specially-crafted request to UDP port 53 to cause the server to crash.
References: [XFDB-75884] [BID-53704] [SECUNIA-49301]

TP-Link TL-WR886N 7.0 1.1.0 devices allow remote attackers to cause a denial of service (Tlb Load Exception) via crafted DNS packets to port 53/udp.
References: [CVE-2018-19528]

MikroTik RouterBOARD v6.39.2 and v6.40.5 allows an unauthenticated remote attacker to cause a denial of service by connecting to TCP port 53 and sending data that begins with many '\0' characters, possibly related to DNS.
References: [CVE-2017-17537], [EDB-43200]
53 tcp,udp Domain Name System (DNS) (official) Wikipedia
53 tcp trojan ADM worm, li0n, MscanWorm, MuSka52 Trojans
53 udp applications Lineage II Portforward
53,80,443,10070-10080 tcp applications Socom, Socom 2. Also uses ports 6000-6999,10070 udp Portforward
53,80,443,10070,10080 tcp applications Twisted Metal Black Online (also uses ports 6000-6999 udp) Portforward
53 tcp ADMworm [trojan] ADM worm Neophasis
53 tcp Lion [trojan] Lion Neophasis
53 tcp threat Civcat Bekkoame
53 tcp threat Esteems Bekkoame
53 tcp threat W32.Dasher Bekkoame
53 tcp threat W32.Spybot Bekkoame
53 tcp,udp domain Domain Name Server IANA
13 records found
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Related ports: 80  88  443  444  953  1025  3074  21211  

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External Resources
SANS Internet Storm Center: port 53

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.

Please use the "Add Comment" button below to provide additional information or comments about port 53.
  User Reviews/Comments:
by clairmont32 - 2014-02-18 12:21
Trojan.Zbot uses a 12 character DGA query for internet connectivity checks.
by Saw - 2020-10-28 13:05
I checked this but I don't know alot about computers. I ran a testy on my wifi and pretty 53 came up as Google 53 or 53 Google???
by Philip - 2020-10-29 20:50
Please use our forums for questions, comments here are intended for adding information about this specific port.
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