There is a vulnerability that permits unauthorized access to several switch and router products manufactured by Cisco Systems. An attacker who gains access to an affected device can read its configuration, creating an information leak.
Certain versions of the Cisco Internetworking Operating System (IOS) contain a user interface defect that accidentally creates a read-only Simple Network Management Protocol (SNMP) community string. This string is created if a "snmp-server host" command is issued on a device whose configuration does not already contain a community string of "community". Once created, this string cannot be permanently removed without installing a patch from Cisco. Although the community string provided by this vulnerability cannot be used to modify the configuration of affected devices, the read-only access that it provides may allow an attacker to learn a read-write community string.
This vulnerability allows attackers to read any SNMP object present on an affected device. Attackers exploiting this vulnerability can gather information about network topology and system administration contacts.
Cisco has released an advisory that provides a list of affected products, along with instructions for obtaining fixed software. Because there are many possible combinations of hardware and software configurations, the CERT/CC recommends that all users of IOS and software consult the following Cisco Security Advisory:
Cisco has provided detailed information on implementing workarounds to address this issue. Please consult the Cisco advisory referenced above.
The CERT/CC thanks Cisco Systems for providing a description of this vulnerability and a patch to address it.
This document was written by Jeffrey P. Lanza and is based on information obtained from a Cisco Security Advisory.
|Date First Published:||2001-05-01|
|Date Last Updated:||2002-03-05 22:52 UTC|