Руководство Пользователя для Cisco Cisco Email Security Appliance C160
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Cisco AsyncOS 9.1 for Email User Guide
Chapter 16 File Reputation Filtering and File Analysis
Overview of File Reputation Filtering and File Analysis
File Processing Overview
Evaluation of file reputation and sending of files for analysis occur immediately after anti-virus
scanning, regardless of verdicts from previous scanning engines, unless a final action has been taken on
the message.
scanning, regardless of verdicts from previous scanning engines, unless a final action has been taken on
the message.
Communications between the appliance and the file reputation service are encrypted and protected from
tampering.
tampering.
After a file’s reputation is evaluated:
•
If the file is known to the file reputation service and is determined to be clean, the message continues
through the workqueue.
through the workqueue.
•
If the file reputation service returns a verdict of malicious for any attachment in the message, then
the appliance applies the action that you have specified in the applicable mail policy.
the appliance applies the action that you have specified in the applicable mail policy.
•
If the file is known to the reputation service but there is insufficient information for a definitive
verdict, the reputation service returns a reputation score based on characteristics of the file such as
threat fingerprint and behavioral analysis. If this score meets or exceeds the configured reputation
threshold (you should not change the default threshold), the appliance applies the action that you
have configured in the mail policy for files that contain malware.
verdict, the reputation service returns a reputation score based on characteristics of the file such as
threat fingerprint and behavioral analysis. If this score meets or exceeds the configured reputation
threshold (you should not change the default threshold), the appliance applies the action that you
have configured in the mail policy for files that contain malware.
•
If the reputation service has no information about the file, and the file does not meet the criteria for
analysis, the file is considered clean and the message continues through the workqueue.
analysis, the file is considered clean and the message continues through the workqueue.
•
If the reputation service has no information about the file, and the file meets the criteria for files that
can be analyzed (see
can be analyzed (see
), then the file is
considered clean and is optionally sent for analysis. You can configure the appliance to quarantine
files sent for analysis instead of releasing them immediately to the workqueue. See
files sent for analysis instead of releasing them immediately to the workqueue. See
.
•
If file reputation information is unavailable, for example because the connection with the cloud
service timed out, the appliance applies the action that you have specified for unscannable
attachments in the applicable mail policy.
service timed out, the appliance applies the action that you have specified for unscannable
attachments in the applicable mail policy.