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Why are packet filter firewalls not always a competent countermeasure against instant messaging (IM) attacks?

Why are packet filter firewalls not always a competent countermeasure against instant messaging (IM) attacks?

PrepAway - Latest Free Exam Questions & Answers

A.
They are the best type of countermeasure for this type of threat.

B.
They cause an internal denial of service when dealing with IM traffic.

C.
They can detect worms that are being transmitted through this traffic type.

D.
IM clients can reconfigure themselves to work on a port that is open on the firewall.

Explanation:
Many firewalls do not have the capability to scan for this type of
traffic to uncover suspicious activity. Blocking specific ports on the firewalls is
not usually effective because IM traffic can use common ports that need to be open
(HTTP port 80 and FTP port 21). Many IM clients will auto-configure themselves to
work on another port if their default port is unavailable and blocked by the
firewall.

15 Comments on “Why are packet filter firewalls not always a competent countermeasure against instant messaging (IM) attacks?

  1. Syed Javed says:

    A packet contains source IP/Port and Destination IP/Port and as the firewall can be set to block ports that messengers commonly use. A smart user can always change the port and thus enable his messaging functionality that is why packet filter firewalls aren’t always a competent counter measure for IM’s. Answer should be D.




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  2. Chutuo says:

    People, the CISSP test is above all a test of your understanding of the English language, or whatever language they are using to test you. If your command of the language is approximative, then you might have issues understanding what they are asking you.




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