Rule:

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Sid:
1951

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Summary:
This event is generated when an attempt is made to mount a specific file system exported through Network File System (NFS). 

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Impact:
Remote access.  This mount request can give an attacker remote access to an NFS directory.

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Detailed Information:
The mountd Remote Procedure Call (RPC) implements the NFS mount protocol.  When an NFS client requests a mount of an NFS file system, mountd examines the list of exported file systems.  If the NFS client is permitted access to the requested file system, mountd returns a file handle for the requested directory.  An attacker or legitimate NFS client may request a mount of a specific file system.

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Affected Systems:
All systems running NFS.

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Attack Scenarios:
An attacker may attempt a mount of an NFS directory to read or change files.

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Ease of Attack:
Simple.   

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False Positives:
If a legitimate remote user is allowed to mount NFS file systems, this rule may trigger.

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False Negatives:
None Known.

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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:


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