In contrast to IDSs, which rely on signature files to identify an attack as (or after) it happens, an intrusion prevention
system (IPS) predicts an attack before it occurs. It does this by monitoring key areas of a computer system and
looking for “bad behavior,” such as worms, Trojans, spyware, malware and hackers. It complements firewall,
antivirus and antispyware tools to provide complete protection from emerging threats. It is able to block new
(zero-day) threats that bypass traditional security measures since it does not rely on identifying and distributing threat
signatures or patches.
IDS Policy
An IDS policy should establish the action to be taken by security personnel in the event that an intruder is detected.
Actions may include:
• Terminate the access: If there is a significant risk to the organization’s data or systems, immediate termination is
the usual procedure.
• Trace the access: If the risk to the data is low, the activity is not immediately threatening, or analysis of the entry
point and attack method is desirable, the IDS can be used to trace the origin of the intrusion. This can be used to
determine and correct any system weaknesses and to collect evidence of the attack that may be used in a subsequent
court action.
In either case, the action required should be determined by management in advance and incorporated into a policy.
This will save time when an intrusion is detected, which may impact the possible data loss.