Vulnerability Note VU#118125

AIX FTP server may not properly timeout ephemeral data ports

Overview

The IBM AIX FTP server may be vulnerable to a denial-of-service condition when passive data ports are not closed properly.

I. Description

IBM AIX includes an FTP server, ftpd, which allows files to be transferred between hosts with the FTP protocol. This server is vulnerable to a condition where an attacker may be able to utilize all available ephemeral ports on the system. When the ephemeral port range is exhausted, no more ports are available for the system to use for an indefinite period of time, resulting in a system-wide network-based denial of service. Additionally, the memory usage caused by the sockets in use by ftpd may also create a local denial of service condition by limiting system resources available to other processes. AIX 5.1, 5.2, and 5.3 are affected.

II. Impact

A remote, authenticated user may be able to limit system and network resources and cause a denial-of-service condition. If anonymous FTP access is allowed, anonymous users are considered to be authenticated and may cause the same denial-of-service conditions.

III. Solution

Apply An Update

Please contact IBM or your vendor for information on resolutions, workarounds, updates, and fixes.

Systems Affected

Vendor	Status	Date Updated
IBM	Vulnerable	7-Jul-2005

References

http://www-1.ibm.com/servers/aix/
http://www.faqs.org/rfcs/rfc959.html
http://www.faqs.org/rfcs/rfc1579.html

Credit

Thanks to Matt Mello and IBM for reporting this vulnerability.

This document was written by Ken MacInnis.

Other Information

Date Public	07/07/2005
Date First Published	07/07/2005 03:37:35 PM
Date Last Updated	07/07/2005
CERT Advisory
CVE Name
Metric	1.77
Document Revision	6

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