UDP denial of service attacks
| udp-dos (464) |  Medium Risk |
Description:
Denial of Service attacks can occur when a connection is made between two UDP services. The chargen (port 19) and echo (port 7) services can be spoofed into sending data from one service to another. This action causes an infinite loop and creates a denial of service attack. The attack can consume increasing amounts of network bandwidth, causing loss of performance or a total shutdown of the affected network segments. This attack can effectively disable your Unix server by causing it to spend all its time processing packets that it has echoed back to itself.
Consequences:
Denial of Service
Remedy:
In general, disable and filter echo and chargen services, as well as unused UDP services.
On Windows NT systems, install Windows NT 4.0 Service Pack 4 to mitigate this problem, or the post-SP3 hotfix. See Microsoft Knowledge Base Article Q154460 in the References.
On Windows systems in general, disable or uninstall Simple TCP/IP Services if this service is not needed.
References:
- BugTraq Mailing List, Wed, 21 Oct 1998 12:00:36 -0400: Re: Alert: IE 4.0 Security Zone compromise.
- Caldera International, Inc. Security Advisory SA-1997.33: Vulnerabilities in "inetd" in netkit-base-0.10-1.
- CERT Advisory CA-1996-01: UDP Port Denial-of-Service Attack.
- Cisco Systems White Paper: Defining Strategies to Protect Against UDP Diagnostic Port Denial of Service Attacks.
- Microsoft Knowledge Base Article 154460: Denial of Service Attack Against WinNT Simple TCP/IP Services.
- Novell Technical Information Document #2946023: TCPIP blocking ports (7, 9, 19, etc).
Platforms Affected:
- Apple Mac OS
- Cisco IOS
- Compaq Tru64
- Data General DG/UX
- HP HP-UX
- IBM AIX
- IBM OS2
- Linux Kernel
- Microsoft Windows 2000
- Microsoft Windows 2003 Server
- Microsoft Windows 95
- Microsoft Windows 98
- Microsoft Windows 98SE
- Microsoft Windows Me
- Microsoft Windows NT 4.0
- Microsoft Windows XP
- Novell NetWare 4.11
- Novell NetWare 5.0
- Novell NetWare
- SCO SCO Unix
- SGI IRIX
- Sun Solaris
- WindRiver BSDOS
Reported:
Feb 01, 1996
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