IM Security & Firewalls: Types, Vulnerabilities & Solutions, Slides of Network security

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1

Instant Messaging Security and

Firewalls

2

IM Security and Firewalls

• IM types
• IM vulnerabilities
• New IM products
• Firewalls
  • NAT, PAT
  • Packet filtering
  • Proxy Server
  • Stateful packet inspection
  • Access control lists

4

Instant Messenger

• IM uses real-time communication
• IM can be used only with clients who are online at

that time

• IM operates in peer-to-peer or peer-to-network

models

• IM transports sensitive and confidential data
• IM sends plain text over public networks
• AIM is the most used IM system followed by ICQ

5

Instant Messenger

• IM uses username and password for

authentication

• IM requires immediate response, unlike

email

• IM can transfer files

7

IM Vulnerabilities

• IM uses both TCP and UDP ports that are

not usually monitored

• IM uses higher range ports that are usually

not monitored

• Different IMs use different set of ports

8

New IM products

• Encryption is available with IM products on

an optional basis

• A firewall can block all IM ports
• Enterprise AIM and Trillian are two

products that provide encryption

10

Firewalls

• Packet filtering firewalls are basically

routers with advanced filtering techniques.

Cisco calls packet filters as Access Control

Lists (ACLs)

• Sample Cisco IOS command for ACL: access-list 101 permit tcp any 1.2.3.4 0.0.0.0 eq 80 access-list 101 deny ip any 1.2.3.4 0.0.0.0 - r u

11

Firewalls

• Proxy servers are application gateways
• Proxies are partially aware of protocol states and

fully aware of application states

• Proxies are rarely transparent to users
• Proxies are resource intensive
• Considered to be first generation firewalls
• Proxies are not easily scalable
• SOCKS is an example of a proxy server

13

DMZ

• Demilitarized Zone is the area between the

outside world and the trusted internal

network where publicly accessed servers are

placed

• Bastion hosts are computers that reside in

the DMZ and are exposed to attacks

14

DMZ diagram

Internet

Firewall

PC

PC

Public Server

PC

PC

Private Server

DMZ

16

References

• www.ceruleanstudios.com has information

about Trillian IM

17

Security Scenario to Solve

1. Firewalls have been the mainstay of

access control that keep intruders out.

However, backdoor entries into firewalls

are left. Research this topic to see how

such backdoor entry points are devised,

why they are needed, what can be done to

minimize attacks through backdoor

entries.