Simple Network Management Protocol (SNMP) is commonly mismanaged by busy administrators and developers. Frequently, you will see default community strings or community strings that are reused throughout the entire organization you are testing. You will want to ensure that your clients are using the most secure version of SNMP and that you cannot simply walk in to a building, unplug a phone, and sniff the community string. Newer versions of SNMP include strong encryption to avoid such flaws.
More than likely you will not find many community strings that are set at default. That is when you must dig into your toolset and earn your pay. There are many utilities that assist in actions such as brute forcing SNMP community names. One favorite is onesixtyone
. This scanner is fast and efficient and will send requests in parallel to speed things up.