From: Whiteside, Larry [contractor] (BAE14@SSP.NAVY.MIL)
Date: Thu Jun 12 2003 - 11:27:27 EDT
I have seen this on numerous occasions. Mainly on Unix or AIX systems and mainframes. It is the way they handle the number of invalid tcp packet request. For each invalid tcp port that is probed, some AIX/Unix systems create a system message that takes a little bit more of the processor.
When you figure that there may be a few hundred request per second (depending on the scanner), then the system processor can quickly become overburdened. I would monitor that during the scan. Otherwise, I would monitor the system to see what processes get overwhelmed during a tcp scan. At least one of the processes on the system is going to increase. That may be your culprit.
Hope this helps.
L
***************************
Larry Whiteside Jr.
Sr. Security Engineer
-----Original Message-----
From: steve.x.jones@royalmail.com [mailto:steve.x.jones@royalmail.com]
Sent: Thursday, June 12, 2003 7:23 AM
To: pen-test@securityfocus.com
Subject: Port scan causing system crashes
Hello
Please can you help? Has any-one else out there had issues with NMAP port scans
(or any other port scanner) causing systems to crash?
I use Nessus to baseline the security of our systems and have twice had problems
caused by the NMAP port scan on clustered unix boxes running our enterprise
applications. NOTE - it was the initial port scan that caused the problems, not
the subsequent vulnerability assessment.
I've done a quick Google search and found confirmation for one of the systems -
BUGTRAQ Vulnerability 3358, "IBM HACMP Port Scan Denial of Service Vulnerability",
the other was a bespoke app running on some HP UX boxes.
Does any-one know of other systems that fall over with a simple port scan?
Up til now I've been running port scans happily across our subnets to look for
rogue FTP, SMTP, HTTP etc, obviously I'll have to take more care now...
Thanks in advance for any help.
Steve
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