GEN:SID | 1:1893 |
Message | SNMP missing community string attempt |
Summary | This event is generated when SNMP communications do not contain a community name.
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Impact | Medium to Serious. Depending on if the community string was for read-only, read-create or read-write an attacker could gain a varying level of access to a system.
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Detailed Information | An SNMP community string is the authentication process that a host running SNMP uses to grant access. By supplying a blank community string and attacker may be attempting to gain access to SNMP functionality for a device that has not been configured correctly.
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Affected Systems | Numerous. Routers, switches, servers, NAS systems, many others.
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Attack Scenarios | An attacker can launch a scan of all network attached devices looking for port 161 (UDP) and then attempt to gain access using SNMP.
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Ease of Attack | Simple. There are many free SNMP "tree walking" programs, an example of such is getIF.
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Corrective Action | Ensure that all devices using SNMP have a community string assigned.
Make sure that all devices that have SNMP turned on have complex passwords assigned.
Disable unneeded WRITE / CREATE community strings.
Since SNMP traffic is not encrypted, use a packet filtering firewall to restrict SNMP communications to the protected network.
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Additional References | GetIF: http://www.wtcs.org/snmp4tpc/getif.htm
CVE: http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-1999-0517
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Rule References | bugtraq: 2112
cve: 1999-0517
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