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Antivirus on a PC accessing two Networks

By The_scanguru ·

I have a PC with an Antivirus virus file updated Automatically all the time. This PC is connected to two different networks A and B through 2 Network cards. The network A is fully secured and each PC on network A has an antivirus with automatic upgrade, but on the network B none of the PC are protected because they can't be contaminated (can't access Internet and have no USB, Floppy or CD drive). Can a virus that can only come from the protected network A can contaminate the network B without contaminating network A? In the other hand I understand that if Network A is contaminated B will be too.


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by Gigelul In reply to Antivirus on a PC accessi ...

There are files which are transfered from A to B, B can access files from A, shares in A used by B or shares in B used by A?
If the answer for one of this is yes, then the B network it is not protected.
That PC, with 2 NICs, itself is a problem!

100% protection is impossile!

I'll give you an example which happened to me in 2002:
- antivirus updated (a good one)
- at 5:30 AM a clock, I received a suspect email
- at ~10 AM a clock, I received a new update for my antivirus
That email was virused with an unknown virus (undetectable). 5 hours latter that virus becomes a known virus...

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by kalaivanan.vvelan In reply to Antivirus on a PC accessi ...

Unless a network is completely physically isolated, it can always be Infected.
Take Sober worm for example it took antivirus vendors over 8hrs to identify and buid a definition file. In this time if your system with 2 network card gets infected and you connect to Network B, all the systems in Network B will be infected.
For Viruses and worms of lower importance, most vendors provide a definition file only once in 7 days. hence anytime in these 7 days if your system gets infected, it will spread to network B.

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by Kryptos In reply to Antivirus on a PC accessi ...

Yes B network can also be compramised.If you have file /email sharing or access across networks.

If you have enabled routing /packet forwarding on the gateway PC (whihc is connected to both network).

Newer viruses dosn't requre file or e-mail or even user interaction to spread and infect. just the connectivity is enough.


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by GDoC In reply to Antivirus on a PC accessi ...

Any system that has connection to network B can act as a gateway into network A. This is the reason that VPN users are such bugbears to IT security.
Even if you have a bi-directional personal FW in place, if the user permits a connection, it is out of the hands of the FW as it will forward accepted port request (such as 1433/1434) to a SQL server if the local requesting application has been compromized. This is the basis of zombie attacks.

As others have stated; the only secure system is one that has no data, and isn't turned on/connected.

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by wlbowers In reply to Antivirus on a PC accessi ...

If there is a network path they can be infected.

There are virus and trojans that hunt for network connections and port connections. Then they infect.

Good Luck


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