Cisco Cisco Email Security Appliance C160 Mode D'Emploi

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Cisco AsyncOS 8.5.6 for Email User Guide
 
Chapter 14      Outbreak Filters
  Managing Outbreak Filters
Outbreak Lifecycle and Rules Publishing
Very early in a virus outbreak’s life cycle, broader rules are used to quarantine messages. As more 
information becomes available, increasingly focused rules are published, narrowing the definition of 
what is quarantined. As the new rules are published, messages that are no longer considered possible 
virus messages are released from quarantine (messages in the outbreak quarantine are rescanned as new 
rules are published).
Managing Outbreak Filters
Log in to the Graphical User Interface (GUI), select Security Services in the menu, and click Outbreak 
Filters.
Table 14-3
Example Rules for an Outbreak Lifecycle 
Time
Rule Type
Rule Description
Action
T=0
Adaptive Rule 
(based on past 
outbreaks)
A consolidated rule set based 
on over 100K message 
attributes, which analyzes 
message content, context and 
structure
Messages are automatically quarantined 
if they match Adaptive Rules
T=5 min Outbreak Rule
Quarantine messages 
containing .zip (exe) files
Quarantine all attachments that are .zips 
containing a .exe
T=10 
min
Outbreak Rule
Quarantine messages that have 
.zip (exe) files greater than 50 
KB
Any message with .zip (exe) files that 
are less than 50 KB would be released 
from quarantine
T=20 
min
Outbreak Rule
Quarantine messages that have 
.zip (exe) files between 50 to 55 
KB, and have “Price” in the file 
name
Any message that does not match this 
criteria would be released from 
quarantine 
T=12 
hours
Outbreak Rule
Scan against new signature 
All remaining messages are scanned 
against the latest anti-virus signature