Rule

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Sid
133-23

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Summary:
This event is generated when the dcerpc2 preprocessor detects anomalous network traffic.

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Impact:
Unknown. This is an indication of anomalous behaviour between networked assets.

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Detailed Information:
This event is generated when the dcerpc2 preprocessor detects anomalous network traffic.

When a Session Setup AndX request is sent to the server, the server responds (if the client successfully authenticates) which a user id or login handle. This is used by the client in subsequent requests to indicate that it has authenticated. A Logoff AndX request is sent by the client to indicate it wants to end the session and invalidate the login handle. With commands that are chained after a Session Setup AndX request, the login handle returned by the server is used for the subsequent chained commands. The combination of a Session Setup AndX command with a chained Logoff AndX command, essentially logins in and logs off in the same request and is anomalous behavior. The preprocessor will generate this event if it sees this.

This event can be controlled using the ((dce2)) configuration options.

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Affected Systems:
All systems using NetBIOS DCERPC or SMB file and print sharing

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Attack Scenarios:
 

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Ease of Attack:
Simple.

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False Positives:
None known.

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False Negatives:
None known.

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Corrective Action:


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Contributors:
Sourcefire Vulnerability Research Team


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Additional References:


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