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Virus 18/11/2018.

Published byGertrud Krüger Modified over 6 years ago

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Presentation on theme: "Virus 18/11/2018."— Presentation transcript:

1 Virus 18/11/2018

2 Memory-resident virus
Runs whenever certain interrupts occur. 18/11/2018

3 Encrypted virus To conceal signature. 18/11/2018

4 Unix address space Low address Program Statically allocated data Stack
High address 18/11/2018

5 Procedure call E.g., finger aabbcc aa bb cc Buffer area allocated
by called fingerd (512 bytes) [PC] ret Return address para2 para1 Stack High address 18/11/2018

6 Buffer overflow E.g., finger aabb…zz zz aa bb cc … Malicious program
(binary) [PC] zz Return address para2 para1 Stack 18/11/2018

7 Epidemic Worm Bootstrap proper Worm proper New victim Infested machine
rsh attack Worm proper Bootstrap finger attack sendmail attack Upload request Worm proper New victim Infested machine 18/11/2018

8 Firewall location Internet Intranet Intranet Packet filter and/or
- Application gateway 18/11/2018

9 Typical configurations
DMZ 18/11/2018

10 (a) Filtering router Mail server (port=25) Filtering router Internet
Intranet 18/11/2018

11 Filtering router implementation
Action Our host Port Their host Block * SPIGOT Allow Our-MailServ 25 Our-WebServ 80 18/11/2018

12 (b) Filtering router and Bastion host
Internet Protected Intranet Router only permits traffic to/from bastion host 18/11/2018

13 (c) Demilitarized Zone (DMZ)
Modem access Bastion host Protected intranet inside router Internet outside router Web server DMZ 18/11/2018

14 HTTP proxy 18/11/2018

15 Local HTTP proxy Proxy Server Internet (B) HTTP (A) Proxy HTTP
Client is configured to use proxy HTTP via (B). (B) Sends GET page.html to on behalf of (A). 18/11/2018

16 RMI thru firewall HTTP server Internet RMI server client_stub port
POST “data” to java-rmi.cgi?forward=<rmiServerPort> 18/11/2018

17 Private network 18/11/2018

18 Hybrid network 18/11/2018

19 Virtual private network
18/11/2018

20 Addressing in a VPN 18/11/2018

21 Tunneling 18/11/2018

22 Virtual Private Network (VPN)
Internet Intranet B Intranet A Tunneling Router RA Router RB RB Data Station 200 Station 100 encrypted 18/11/2018

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