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Rule:
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Sid:
2018
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Summary:
This event is generated when a request is made to list remotely mounted Network File System (NFS) directories.
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Impact:
Information disclosure. This can allow an attacker to discover NFS file systems that have been mounted.
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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 list of mounted file systems.
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Affected Systems:
All systems running NFS.
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Attack Scenarios:
An attacker may attempt to list the mounted NFS file systems as a precursor to mounting them to read or change a specific file.
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Ease of Attack:
Simple.
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False Positives:
If a legitimate remote user is allowed to list mounted 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 Brian Caswell <bmc@sourcefire.com>
Sourcefire Research Team
Judy Novak <judy.novak@sourcefire.com>
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Additional References:
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