Ascom COLTSOHO 2.0.21,Brocade Fabric OS 2.1.2,Cisco IOS 11.2,Cray MatchBox Router 2.0.1,Windows 98,Windows NT 4.0,Solaris 2.6,Xyplex Router 6.1.1 SNMP World Writeable Community Vulnerability

source: http://www.securityfocus.com/bid/986/info

In a number of network devices/operating systems, some default communites are world-writeable and therefore allow remote users to configure properties of the device/OS without any authorization (other than knowledge of the community name).

Some of the common default communities/vendors are:

public (ascend,cisco,bay networks (nortel),microsoft,sun,3com, aix)
private (cisco,bay networks (nortel),microsoft,3com, brocade, aix, netapp)
write (ascend, very common)
"all private" (sun)
monitor (3com)
manager (3com)
security (3com)
OrigEquipMfr (brocade)
"Secret C0de" (brocade)
admin
default
password
tivoli
openview
community
snmp
snmpd
system (aix, others)
the name of the router (ie, 'gate')

The attacks can include manipulating routing tables and corrupting ARP caches, which can lead to further compromise. This type of vulnerability has been seen for quite some time; more information on it is listed in the credit section.

snmpset hostname {private|public} interfaces.ifTable.ifEntry.ifAdminStatus.1 i 2

This will make the primary interface on the target host (with a default community of public or private) change state to two, which is "down".