On every Nectus installation that we conducted I noticed that on average each company has around 10% of network devices that are configured with well-known snmp v2 community strings: public/private.
This is as bad as using “cisco/cisco” as your SSH credentials. That is major security loophole as even read-only string “public” gives possible attacker complete view of the devices’ routing table, interface descriptions, interface IPs, device S/N, list of CDP neighbors with their IPs.
It is fairly easy to discover these devices by adding secondary SNMP profile to your favorite NMS and checking if there is a sudden spike in number of discovered devices.
Problem is so wide-spread that we added discovery of these devices to be a part of standard Nectus network discovery routine.
SNMP v3 does not have this issue as it has way more parameters that has to be configured, plus it gives access to strong encryption, but for some reason adoption rates for SNMP v3 is low comparing to SNMP v2.