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Port 137 Details
known port assignments and vulnerabilities
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| Port(s) |
Protocol |
Service |
Details |
Source |
| 137 |
tcp,udp |
netbios-ns |
NetBIOS is a protocol used for File and Print Sharing under all current versions of Windows. While this in itself is not a problem, the way that the protocol is implemented can be.
NetBios services:
NETBIOS Name Service (TCP/UDP: 137)
NETBIOS Datagram Service (TCP/UDP: 138)
NETBIOS Session Service (TCP/UDP: 139)
By default, when File and Print Sharing is enabled it binds to everything, including TCP/IP (The Internet Protocol), rather than just the local network, meaning your shared resources are available over the entire Internet for reading and deletion, unless configured properly. Any machine with NetBIOS enabled and not configured properly should be considered at risk. The best protection is to turn off File and Print Sharing, or block ports 135-139 completely. If you must enable it, use the following guidelines:
1. Use strong passwords, containing non-alphanumeric characters.
2. Attach "$" at the end of your share names (the casual snooper using net view might not see them).
3. Unbind File and Print Sharing from TCP/IP and use NetBEUI instead (it's a non-routable protocol).
4. Block ports 135-139 in your router/firewall.
Keep in mind that you might still be leaking out information about your system that can be used against you (such as your computer and workgroup names) to the entire Internet, unless ports are filtered by a firewall.
There is also a Critical Windows RPC vulnerability affecting ports 135,139 and 445, as detailed here: MS Technet Security Bulletin [MS03-026]
The following trojans/backdoors also use these ports: Chode, God Message worm, Msinit, Netlog, Network, Qaz
W32.HLLW.Moega [Symantec-2003-080813-3234-99] (2003.08.08) - worm with backdoor capabilities, opens TCP ports 139 and 445.
W32.Crowt.A@mm [Symantec-2005-012310-2158-99] (2005.01.23) - mass mailing worm, opens a backdoor, logs keystrokes. Uses ports 80 and 137.
W32.Reidana.A [Symantec-2005-032515-4042-99] (2005.03.27) - worm that spreads using the MS DCOM RPC vulnerability (MS Security Bulletin [MS03-026]) on port 139. The worm attempts to download and execute a remote file via FTP. Opens TCP port 4444.
Windows Internet Naming Service (WINS) also uses this port (UDP).
Sygate Personal Firewall comes with a default rule set that blocks all udp requests, however if udp requests originates from source port 137 or 138 they are allowed, thus a malicious person could get access to all open udp ports on a target merely by sending all requests from source port 137 or 138.
References: [SECUNIA-7930] |
SG
|
| 137 |
tcp,udp |
|
NetBIOS NetBIOS Name Service (official) |
Wikipedia
|
| 137 |
tcp |
trojan |
Chode, Nimda |
Trojans
|
| 137 |
udp |
trojan |
Bugbear, Msinit, Opaserv, Qaz |
Trojans
|
| 137 |
tcp |
Chode |
[trojan] Chode |
Neophasis
|
| 137 |
tcp |
Qaz |
[trojan] Qaz |
Neophasis
|
| 137 |
udp |
Msinit |
[trojan] Msinit |
Neophasis
|
| 137 |
udp |
threat |
Femot |
Bekkoame
|
| 137 |
udp |
threat |
Msinit |
Bekkoame
|
| 137 |
tcp |
threat |
Chode |
Bekkoame
|
| 137 |
tcp,udp |
netbios-ns |
NETBIOS Name Service |
IANA
|
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11 records found
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jump to:
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Related ports: 135 138 139 445
« back to SG Ports
External Resources
SANS Internet Storm Center: port 137
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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