Vulnerability Note VU#178024

Cisco IOS vulnerable to deferred DoS via SYN scan to certain TCP port ranges

Overview

Cisco Internetwork Operating System (IOS) may reload unexpectedly after being scanned on certain ports.

I. Description

Certain versions of Cisco IOS contain a vulnerability that allows the router to enter an unstable state after receiving a connection attempt on any TCP port in the following ranges: 3100-3999, 5100-5999, 7100-7999, and 10100-10999. In this state, the router will reload at the next execution of "show running-config," "write memory," or any command that causes the configuration file to be accessed.

II. Impact

Attackers may cause Cisco routers to reload and cause a denial of service.

III. Solution

Review Cisco Systems's security advisory to determine which versions of IOS are vulnerable and which version you should obtain to eliminate this vulnerability. The advisory is available at:

http://www.cisco.com/warp/public/707/ios-tcp-scanner-reload-pub.shtml
None.

Systems Affected

Vendor	Status	Date Notified	Date Updated
Cisco	Vulnerable	25-Oct-2001

References

http://www.cisco.com/warp/public/707/ios-tcp-scanner-reload-pub.shtml
http://www.securityfocus.com/bid/2804

Credit

Thanks to Cisco Systems for reporting this vulnerability.

This document was written by Shawn Van Ittersum.

Other Information

Date Public:	2001-05-24
Date First Published:	2001-10-25
Date Last Updated:	2001-10-25
CERT Advisory:
CVE-ID(s):	CAN-2001-0750
NVD-ID(s):	CAN-2001-0750
US-CERT Technical Alerts:
Severity Metric:	11.81
Document Revision:	11

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