Cisco Cisco Email Security Appliance C170 Guia Do Utilizador
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AsyncOS 9.1.2 for Cisco Email Security Appliances 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.
from 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, 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, 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 (see
analysis (see
), the file is considered clean and
the message continues through the workqueue.
•
If you have enabled File Analysis, and the reputation service has no information about the file, and
the file meets the criteria for files that can be analyzed (see
the file meets the criteria for files that can be analyzed (see
), then the file is considered clean and is optionally sent for analysis.
•
You can configure the appliance to quarantine messages with attached files that are sent for analysis,
instead of releasing them immediately to the workqueue. See
instead of releasing them immediately to the workqueue. See
.
•
If file reputation information is unavailable, for example because the connection with the service
timed out,. the appliance applies the action that you have specified for unscannable attachments in
the applicable mail policy.
timed out,. the appliance applies the action that you have specified for unscannable attachments in
the applicable mail policy.