Rule:

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Sid:
593

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Summary:
This event is generated when an attempt is made through a portmap GETPORT request to discover the port where the Remote Procedure Call (RPC) snmpXdmi is listening.

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Impact:
Information disclosure.  This request is used to discover which port snmpXdmi is using.  Attackers can also learn what versions of the snmpXdmi protocol are accepted by snmpXdmi.

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Detailed Information:
The portmapper service registers all RPC services on UNIX hosts. It can be queried to determine the port where RPC services such as snmpXdmi run.  Simple Network Management Protocol (SNMP) and Desktop Management Interface (DMI) are remote management protocols.  The snmpXdmi RPC service translates between SNMP and DMI, allowing the use of either or both.  There is a buffer overflow when translating DMI to SNMP that allows access with the privilege level of snmpXdmi.

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Affected Systems:
Sun Solaris 2.6, 7.0, and 8.0.

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Attack Scenarios:
An attacker can query the portmapper to discover the port where snmpXdmi runs.  This may be a precursor to accessing snmpXdmi.

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Ease of Attack:
Simple.  

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False Positives:
If a legitimate remote user is allowed to access snmpXdmi, this rule may trigger.

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False Negatives:
This rule detects probes of the portmapper service for snmpXdmi, not probes of the snmpXdmi service itself. Because RPC services often listen on fairly arbitrary ports, it may not be possible to detect misuses of the snmpXdmi service itself. An attacker may attempt to go directly to the snmpXdmi port without querying the portmapper service, which would not trigger the rule.

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Corrective Action:
Limit remote access to RPC services.

Filter RPC ports at the firewall to ensure access is denied to RPC-enabled machines. 

Disable unneeded RPC services.

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Contributors:
Original rule written by Max Vision <vision@whitehats.com>
Modified by Brian Caswell <bmc@sourcefire.com>
Sourcefire Vulnerability Research Team
Judy Novak <judy.novak@sourcefire.com>

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Additional References:

OSVDB:
http://www.osvdb.org/546

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