Rule:

Sid:
587

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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) statd is listening.

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

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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 statd run.  The statd RPC service manages Network File System (NFS) locks for exclusive access to a remote file. Multiple vulnerabilities that have allowed execution of arbitrary commands as root have been associated with statd.

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Affected Systems:
Multiple; refer to your vendor for specific information.

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

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Ease of Attack:
Simple.  

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

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False Negatives:
This rule detects probes of the portmapper service for statd, not probes of the statd service itself. Because RPC services often listen on fairly arbitrary ports, it may not be possible to detect misuses of the statd service itself. An attacker may attempt to go directly to the statd 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 Research Team
Judy Novak <judy.novak@sourcefire.com>

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Additional References:

Arachnids 
http://www.whitehats.com/info/IDS15


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